1
|
Salton M, Raoult V, Jonsen I, Harcourt R. Niche partitioning and individual specialisation in resources and space use of sympatric fur seals at their range margin. Oecologia 2024; 204:815-832. [PMID: 38568471 PMCID: PMC11062968 DOI: 10.1007/s00442-024-05537-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 03/03/2024] [Indexed: 05/02/2024]
Abstract
Ecological theory predicts niche partitioning between high-level predators living in sympatry as a mechanism to minimise the selective pressure of competition. Accordingly, male Australian fur seals Arctocephalus pusillus doriferus and New Zealand fur seals A. forsteri that live in sympatry should exhibit partitioning in their broad niches (in habitat and trophic dimensions) in order to coexist. However, at the northern end of their distributions in Australia, both are recolonising their historic range after a long absence due to over-exploitation, and their small population sizes suggest competition should be weak and may allow overlap in niche space. We found some niche overlap, yet clear partitioning in diet trophic level (δ15N values from vibrissae), spatial niche space (horizontal and vertical telemetry data) and circadian activity patterns (timing of dives) between males of each species, suggesting competition may remain an active driver of niche partitioning amongst individuals even in small, peripheral populations. Consistent with individual specialisation theory, broad niches of populations were associated with high levels of individual specialisation for both species, despite putative low competition. Specialists in isotopic space were not necessarily specialists in spatial niche space, further emphasising their diverse individual strategies for niche partitioning. Males of each species displayed distinct foraging modes, with Australian fur seals primarily benthic and New Zealand fur seals primarily epipelagic, though unexpectedly high individual specialisation for New Zealand fur seals might suggest marginal populations provide exceptions to the pattern generally observed amongst other fur seals.
Collapse
Affiliation(s)
- Marcus Salton
- School of Natural Sciences, Macquarie University, North Ryde, NSW, 2109, Australia.
- Australian Antarctic Division, Department of Climate Change, Energy, the Environment and Water, Kingston, TAS, 7050, Australia.
| | - Vincent Raoult
- School of Natural Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, 2258, Australia
| | - Ian Jonsen
- School of Natural Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Robert Harcourt
- School of Natural Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| |
Collapse
|
2
|
Robinson AL, Elliott Smith EA, Besser AC, Newsome SD. Tissue-specific carbon isotope patterns of amino acids in southern sea otters. Oecologia 2024; 204:13-24. [PMID: 38227253 DOI: 10.1007/s00442-023-05505-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 12/13/2023] [Indexed: 01/17/2024]
Abstract
The measurement of stable isotope values of individual compounds, such as amino acids (AAs), has become a powerful tool in animal ecology and ecophysiology. As with any emerging technique, questions remain regarding the capabilities and limitations of this approach, including how metabolism and tissue synthesis impact the isotopic values of individual AAs and subsequent multivariate patterns. We measured carbon isotope (δ13C) values of essential (AAESS) and nonessential (AANESS) AAs in bone collagen, whisker, muscle, and liver from ten southern sea otters (Enhydra lutris nereis) that stranded in Monterey Bay, California. Sea otters in this population exhibit high degrees of individual dietary specialization, making this an excellent dataset to explore differences in AA δ13C values among tissues in a wild population. We found the δ13C values of the AANESS glutamic acid, proline, serine, and glycine and the AAESS threonine differed significantly among tissues, indicating possible isotopic discrimination during tissue synthesis. Threonine δ13C values were higher in liver relative to bone collagen and muscle, which may indicate catabolism of threonine for gluconeogenesis, an interpretation further supported by correlations between the δ13C values of threonine and its gluconeogenic products glycine and serine in liver. This intraindividual isotopic variation yielded different ecological interpretations among tissues; for 6/10 of the sea otter individuals analyzed, at least one tissue indicated reliance on a different primary producer source than the other tissues. Our results highlight the importance of gluconeogenesis in a carnivorous marine mammal and indicate that metabolic processes influence AAESS and AANESS δ13C values and multivariate AA δ13C patterns.
Collapse
Affiliation(s)
- Alana L Robinson
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
| | - Emma A Elliott Smith
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
- Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20560, USA
| | - Alexi C Besser
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 85287, USA
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| |
Collapse
|
3
|
Séon N, Brasseur I, Scala C, Tacail T, Catteau S, Fourel F, Vincent P, Lécuyer C, Suan G, Charbonnier S, Vinçon-Laugier A, Amiot R. Determination of water balance maintenance in Orcinus orca and Tursiops truncatus using oxygen isotopes. J Exp Biol 2023; 226:jeb245648. [PMID: 37901938 DOI: 10.1242/jeb.245648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 10/19/2023] [Indexed: 10/31/2023]
Abstract
The secondary adaptation of Cetacea to a fully marine lifestyle raises the question of their ability to maintain their water balance in a hyperosmotic environment. Cetacea have access to four potential sources of water: surrounding salt oceanic water, dietary free water, metabolic water and inhaled water vapour to a lesser degree. Here, we measured the 18O/16O oxygen isotope ratio of blood plasma from 13 specimens belonging to two species of Cetacea raised under human care (four killer whales Orcinus orca, nine common bottlenose dolphins Tursiops truncatus) to investigate and quantify the contribution of preformed water (dietary free water, surrounding salt oceanic water) and metabolic water to Cetacea body water using a box-modelling approach. The oxygen isotope composition of Cetacea blood plasma indicates that dietary free water and metabolic water contribute to more than 90% of the total water input in weight for cetaceans, with the remaining 10% consisting of inhaled water vapour and surrounding water accidentally ingested or absorbed through the skin. Moreover, the contribution of metabolic water appears to be more important in organisms with a more lipid-rich diet. Beyond these physiological and conservation biology implications, this study opens up questions that need to be addressed, such as the applicability of the oxygen isotope composition of cetacean body fluids and skeletal elements as an environmental proxy of the oxygen isotope composition of present and past marine waters.
Collapse
Affiliation(s)
- Nicolas Séon
- Université Claude Bernard Lyon1, LGL-TPE, UMR 5276, CNRS, ENSL, UJM, F-69622 Villeurbanne, France
- Centre de Recherche en Paléontologie - Paris (CR2P), CNRS, Muséum national d'Histoire naturelle, Sorbonne Université, 57 rue Cuvier, 75231 Paris CEDEX 05, France
| | | | | | - Théo Tacail
- Institute of Geosciences, Johannes Gutenberg University, 55128 Mainz, Germany
| | - Sidonie Catteau
- Marineland, 2 Route de la Brague, 06600 Antibes, France
- Réseau Tortues Marines de Méditerranée Française, Société Herpétologique de France, 57 Rue 15 Cuvier, CP4157, 75005 Paris, France
| | - François Fourel
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés, CNRS UMR 5023, Université Claude Bernard Lyon 1, 69622 Villeurbanne, France
| | - Peggy Vincent
- Centre de Recherche en Paléontologie - Paris (CR2P), CNRS, Muséum national d'Histoire naturelle, Sorbonne Université, 57 rue Cuvier, 75231 Paris CEDEX 05, France
| | - Christophe Lécuyer
- Université Claude Bernard Lyon1, LGL-TPE, UMR 5276, CNRS, ENSL, UJM, F-69622 Villeurbanne, France
| | - Guillaume Suan
- Université Claude Bernard Lyon1, LGL-TPE, UMR 5276, CNRS, ENSL, UJM, F-69622 Villeurbanne, France
| | - Sylvain Charbonnier
- Centre de Recherche en Paléontologie - Paris (CR2P), CNRS, Muséum national d'Histoire naturelle, Sorbonne Université, 57 rue Cuvier, 75231 Paris CEDEX 05, France
| | - Arnauld Vinçon-Laugier
- Université Claude Bernard Lyon1, LGL-TPE, UMR 5276, CNRS, ENSL, UJM, F-69622 Villeurbanne, France
| | - Romain Amiot
- Université Claude Bernard Lyon1, LGL-TPE, UMR 5276, CNRS, ENSL, UJM, F-69622 Villeurbanne, France
| |
Collapse
|
4
|
Berthelot F, Unnsteinsdóttir ER, Carbonell Ellgutter JA, Ehrich D. Long-term responses of Icelandic Arctic foxes to changes in marine and terrestrial ecosystems. PLoS One 2023; 18:e0282128. [PMID: 37792685 PMCID: PMC10550166 DOI: 10.1371/journal.pone.0282128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 09/03/2023] [Indexed: 10/06/2023] Open
Abstract
The long-term dynamics of predator populations may be driven by fluctuations in resource availability and reflect ecosystem changes such as those induced by climate change. The Icelandic Arctic fox (Vulpes lagopus) population has known major fluctuations in size since the 1950s. Using stable isotopes analysis of bone collagen over a long-time series (1979-2018), we aimed at identifying the main resources used by Icelandic Arctic foxes during periods of growth and decline to assess if the variations in their population size are linked to fluctuations in the availability of resources. We hypothesized that (1) the decline in Seabird abundance was responsible for the decrease in the fox population; and (2) that the growth in the fox population combined to fluctuations in main resources would lead to an increase in intra-specific competition, ultimately leading to variations in their isotopic niches at the population scale. The isotopic composition of Arctic fox bones differed clearly between inland and coast. Stable isotopes mixing models suggested that marine resources and rock ptarmigans were the most important food source and highlighted a rather stable diet in coastal habitats compared to inland habitats where more fluctuations in dietary composition were observed. Coastal foxes had a broader niche than inland foxes, and there was more variation in niche size in the inland habitat. Our results tend to confirm that a general decline in seabird populations drove the decline in Arctic foxes, especially in coastal habitats. For the inland foxes, our results suggest that the lack of marine resources might have led to an increased use of ptarmigans especially during the most recent period.
Collapse
Affiliation(s)
- Fanny Berthelot
- Department of Arctic and Marine Biology, UiT -The Arctic University of Norway, Tromsø, Norway
| | | | | | - Dorothee Ehrich
- Department of Arctic and Marine Biology, UiT -The Arctic University of Norway, Tromsø, Norway
| |
Collapse
|
5
|
Fraleigh DC, Archer FI, Williard AS, Hückstädt LA, Fleming AH. Possible niche compression and individual specialization in Pacific Arctic beluga ( Delphinapterus leucas) from the 19th to 20th century. Ecol Evol 2023; 13:e10230. [PMID: 37408623 PMCID: PMC10318618 DOI: 10.1002/ece3.10230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 06/08/2023] [Accepted: 06/14/2023] [Indexed: 07/07/2023] Open
Abstract
Cetaceans have shown a potential to be used as sentinel species for tracking environmental change in marine ecosystems, yet our assessment of change is typically limited to recent decades and lacks ecological baselines. Using historical museum specimens, we compared community niche metrics and degree of individual dietary specialization in groups of Pacific Arctic beluga (Delphinapterus leucas) from the 1800s (n = 5) to 1900s (n = 10) using stable carbon and nitrogen isotopes drilled from teeth. Beluga occupied a broader trophic niche and demonstrated a higher degree of individual specialization in the 1800s than in the 1900s. The cause of this shift is difficult to confirm given long timescales and constraints of specimen-based research but could indicate changes in the prey base or competition. The scale and nature of this detected shift provide perspective for continued research on these climate-vulnerable species.
Collapse
Affiliation(s)
- Devin C. Fraleigh
- Center for Marine ScienceUniversity of North Carolina WilmingtonWilmingtonNorth CarolinaUSA
| | - Frederick I. Archer
- Southwest Fisheries Science CenterNational Marine Fisheries Service, National Oceanic and Atmospheric AdministrationLa JollaCaliforniaUSA
| | - Amanda S. Williard
- Department of Biology and Marine BiologyUniversity of North Carolina WilmingtonWilmingtonNorth CarolinaUSA
| | - Luis A. Hückstädt
- Department of Biology and Marine BiologyUniversity of North Carolina WilmingtonWilmingtonNorth CarolinaUSA
- Centre for Ecology and ConservationUniversity of ExeterCornwallUK
| | - Alyson H. Fleming
- Center for Marine ScienceUniversity of North Carolina WilmingtonWilmingtonNorth CarolinaUSA
- Department of Forest & Wildlife EcologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
- National Museum of Natural HistorySmithsonian InstitutionWashingtonDistrict of ColumbiaUSA
| |
Collapse
|
6
|
Teixeira CR, Botta S, Cremer MJ, Marcondes MCC, Pereira LB, Newsome SD, Jorge FGD, Simões-Lopes PC. Ecologically driven differences in individual diet specialization across three populations of Guiana dolphin. Oecologia 2023; 201:397-408. [PMID: 36650314 DOI: 10.1007/s00442-022-05312-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 12/29/2022] [Indexed: 01/19/2023]
Abstract
Populations usually considered foraging generalists may include specialized individuals that feed on a restricted subset of the prey spectrum consumed by the population. By analyzing the time series of δ13C and δ15N values in sequential growth layer groups within tooth dentin, we measured population- and individual-level variation in resource use of three populations of Guiana dolphins (Sotalia guianensis)-Caravelas River, Babitonga Bay, and Norte Bay-along a latitudinal gradient in the southwestern Atlantic Ocean. We show that the Guiana dolphin at Caravelas River is a generalist population consisting of individual dietary specialists, likely due to the absence of other resident dolphin populations thus allowing individuals to target prey across a wide range of habitats. The Babitonga Bay population is also composed of individual specialists potentially due to the selective foraging behavior of some individuals on high-quality prey sources within and near the bay. In contrast, the Norte Bay population comprises individual generalists, which likely reflects its distinctive cohesive social organization, coexistence with two other dolphin species, and an opportunistic foraging strategy in response to resource fluctuations inherent to the southern limit of the species distribution. Although the Guiana dolphin is generally considered to be a dietary generalist at the population level, our findings reveal that the total niche width of populations and the degree of individual diet specialization are highly context dependent, suggesting dietary plasticity that may be related to a latitudinal gradient in resource availability and environmental conditions.
Collapse
Affiliation(s)
- Clarissa R Teixeira
- Laboratório de Mamíferos Aquáticos (LAMAQ), Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil. .,Department of Fisheries, Wildlife, and Conservation Sciences, Marine Mammal Institute, Oregon State University, Newport, OR, USA.
| | - Silvina Botta
- Laboratório de Ecologia e Conservação da Megafauna Marinha (ECOMEGA), Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, Brazil
| | - Marta J Cremer
- Laboratório de Ecologia e Conservação de Tetrápodes Marinhos e Costeiros (TetraMar), Unidade São Francisco do Sul, Universidade da Região de Joinville, São Francisco do Sul, Santa Catarina, Brazil
| | | | - Luiza B Pereira
- Laboratório de Mamíferos Aquáticos (LAMAQ), Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Fábio G Daura Jorge
- Laboratório de Mamíferos Aquáticos (LAMAQ), Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Paulo C Simões-Lopes
- Laboratório de Mamíferos Aquáticos (LAMAQ), Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| |
Collapse
|
7
|
Isotope systematics of subfossil, historical, and modern Nautilus macromphalus from New Caledonia. PLoS One 2022; 17:e0277666. [PMID: 36576896 PMCID: PMC9797077 DOI: 10.1371/journal.pone.0277666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 11/01/2022] [Indexed: 12/29/2022] Open
Abstract
Cephalopod carbonate geochemistry underpins studies ranging from Phanerozoic, global-scale change to outcrop-scale paleoecological reconstructions. Interpreting these data hinges on assumed similarity to model organisms, such as Nautilus, and generalization from other molluscan biomineralization processes. Aquarium rearing and capture of wild Nautilus suggest shell carbonate precipitates quickly (35 μm/day) in oxygen isotope equilibrium with seawater. Other components of Nautilus shell chemistry are less well-studied but have potential to serve as proxies for paleobiology and paleoceanography. To calibrate the geochemical response of cephalopod δ15Norg, δ13Corg, δ13Ccarb, δ18Ocarb, and δ44/40Cacarb to modern anthropogenic environmental change, we analyzed modern, historical, and subfossil Nautilus macromphalus from New Caledonia. Samples span initial human habitation, colonialization, and industrial pCO2 increase. This sampling strategy is advantageous because it avoids the shock response that can affect geochemical change in aquarium experiments. Given the range of living depths and more complex ecology of Nautilus, however, some anthropogenic signals, such as ocean acidification, may not have propagated to their living depths. Our data suggest some environmental changes are more easily preserved than others given variability in cephalopod average living depth. Calculation of the percent respired carbon incorporated into the shell using δ13Corg, δ13Ccarb, and Suess-effect corrected δ13CDIC suggests an increase in the last 130 years that may have been caused by increasing carbon dioxide concentration or decreasing oxygen concentration at the depths these individuals inhabited. This pattern is consistent with increasing atmospheric CO2 and/or eutrophication offshore of New Caledonia. We find that δ44/40Ca remains stable across the last 130 years. The subfossil shell from a cenote may exhibit early δ44/40Ca diagenesis. Questions remain about the proportion of dietary vs ambient seawater calcium incorporation into the Nautilus shell. Values of δ15N do not indicate trophic level change in the last 130 years, and the subfossil shell may show diagenetic alteration of δ15N toward lower values. Future work using historical collections of Sepia and Spirula may provide additional calibration of fossil cephalopod geochemistry.
Collapse
|
8
|
Pantoja-Echevarría LM, Tamburin E, Elorriaga-Verplancken FR, Marmolejo-Rodríguez AJ, Galván-Magaña F, Tripp-Valdez A, Lara A, Jonathan MP, Sujitha SB, Delgado-Huertas A, Arreola-Mendoza L. How to stay together? Habitat use by three sympatric sharks in the western coast of Baja California Sur, Mexico. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:61685-61697. [PMID: 35287199 DOI: 10.1007/s11356-022-19530-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
Sharks are top predators and play an important role in the regulation of marine ecosystems at lower trophic position. Mustelus californicus, Sphyrna zygaena, and Isurus oxyrinchus prove to be important fishery resources along the western coast of Baja California Sur and cohabit the same coastal areas, probably sharing resources. However, our knowledge about ecological dynamics of multiple species coexisting and sharing similar habitat resources is still limited, particularly for predators such as sharks. Therefore, this study focuses on the analysis of trophic ecology of the sharks species, using carbon (13C) and nitrogen (15N) stable isotope values in muscle tissues coupled with trace element concentration (Hg, Se, and Cd) in muscle and hepatic tissues of sharks. The values of δ13C (M. californicus -17.3 ± 1.1‰, S. zygaena -17.9 ± 0.5‰, and I. oxyrinchus -18.3 ± 0.3‰) and δ15N (M. californicus 18.2 ± 1.1‰, S. zygaena 18.4 ± 0.9‰, and I. oxyrinchus 17.8 ± 1.1‰) indicated that these species feed in the Gulf of Ulloa all throughout the year, and for extended periods with similar habitat use and trophic niche. The above-mentioned statement is also a conclusion supported by the significant correlation between isotopic and trace element concentrations in the muscular tissues in all studied species. Thus, the results of the present study emphasize the habitat and niche characteristics of three sympatric sharks off the coast of Baja California Sur, Mexico.
Collapse
Affiliation(s)
| | - Elena Tamburin
- Fundación Alium Pacific, Carrera 26 No. 5C-13, Cali, Colombia
| | | | - Ana Judith Marmolejo-Rodríguez
- Centro Interdisciplinario de Ciencias Marinas (CICIMAR), Instituto Politécnico Nacional (IPN), Avenida IPN, s/n Colonia Playa Palo de Santa Rita, C.P. 23096, La Paz, Baja California Sur, Mexico
| | - Felipe Galván-Magaña
- Centro Interdisciplinario de Ciencias Marinas (CICIMAR), Instituto Politécnico Nacional (IPN), Avenida IPN, s/n Colonia Playa Palo de Santa Rita, C.P. 23096, La Paz, Baja California Sur, Mexico
| | - Arturo Tripp-Valdez
- Centro Interdisciplinario de Ciencias Marinas (CICIMAR), Instituto Politécnico Nacional (IPN), Avenida IPN, s/n Colonia Playa Palo de Santa Rita, C.P. 23096, La Paz, Baja California Sur, Mexico
| | - Ariagna Lara
- Centro Interdisciplinario de Ciencias Marinas (CICIMAR), Instituto Politécnico Nacional (IPN), Avenida IPN, s/n Colonia Playa Palo de Santa Rita, C.P. 23096, La Paz, Baja California Sur, Mexico
| | - M P Jonathan
- Centro Interdisciplinario de Investigaciones y Estudios sobre Medio Ambiente y Desarrollo (CIIEMAD), Instituto Politécnico Nacional (IPN), Calle 30 de Junio de 1520, Barrio la Laguna Ticomán, C.P. 07340, Ciudad de Mexico, Mexico
| | - S B Sujitha
- Escuela Superior de Ingeniería y Arquitectura (ESIA), Instituto Politécnico Nacional (IPN), Unidad Ticoman, Calz. Ticomán 600, Delg. Gustavo A. Madero, C.P. 07340, Ciudad de México (CDMX), Mexico
| | - Antonio Delgado-Huertas
- Laboratorio de Biogeoquímica de Isótopos Estables, Instituto Andaluz de Ciencias de la Tierra IACT (CSIC-UGR), Avda. de las Palmeras, 4, 18100, Armilla, Granada, Spain
| | - Laura Arreola-Mendoza
- Centro Interdisciplinario de Investigaciones y Estudios sobre Medio Ambiente y Desarrollo (CIIEMAD), Instituto Politécnico Nacional (IPN), Calle 30 de Junio de 1520, Barrio la Laguna Ticomán, C.P. 07340, Ciudad de Mexico, Mexico
| |
Collapse
|
9
|
West EH, Jones HH. Human food subsidies drive individual specialization and intrapopulation dietary differences in a generalist predator. Ecosphere 2022. [DOI: 10.1002/ecs2.4246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Elena H. West
- Department of Fisheries, Wildlife and Conservation Biology University of Minnesota Twin Cities Saint Paul Minnesota USA
| | - Harrison H. Jones
- Department of Biology University of Florida Gainesville Florida USA
- Florida Museum of Natural History Gainesville Florida USA
| |
Collapse
|
10
|
Rioux È, Pelletier F, St‐Laurent M. Trophic niche partitioning between two prey and their incidental predators revealed various threats for an endangered species. Ecol Evol 2022; 12:e8742. [PMID: 35342591 PMCID: PMC8933322 DOI: 10.1002/ece3.8742] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/23/2022] [Accepted: 02/28/2022] [Indexed: 11/17/2022] Open
Abstract
Documenting trophic niche partitioning and resource use within a community is critical to evaluate underlying mechanisms of coexistence, competition, or predation. Detailed knowledge about foraging is essential as it may influence the vital rates, which, in turn, can affect trophic relationships between species, and population dynamics. The aims of this study were to evaluate resource and trophic niche partitioning in summer/autumn between the endangered Atlantic‐Gaspésie caribou (Rangifer tarandus caribou) population, moose (Alces americanus) and their incidental predators, the black bear (Ursus americanus) and coyote (Canis latrans), and to quantify the extent to which these predators consumed caribou. Bayesian isotopic analysis showed a small overlap in trophic niche for the two sympatric ungulates suggesting a low potential for resource competition. Our results also revealed that caribou occupied a larger isotopic niche area than moose, suggesting a greater diversity of resources used by caribou. Not surprisingly, coyotes consumed mainly deer (Odocoileus virginianus), moose, snowshoe hare (Lepus americanus), and occasionally caribou, while bears consumed mainly vegetation and, to a lesser extent, moose and caribou. As coyotes and bears also feed on plant species, we documented trophic niche overlap between caribou and their predators, as searching for similar resources can force them to use the same habitats and thus increase the encounter rate and, ultimately, mortality risk for caribou. Although the decline in the Gaspésie caribou population is mostly driven by habitat‐mediated predation, we found evidence that the low level of resource competition with moose, added to the shared resources with incidental predators, mainly bears, may contribute to jeopardize the recovery of this endangered caribou population. Highlighting the trophic interaction between species is needed to establish efficient conservation and management strategies to insure the persistence of endangered populations. The comparison of trophic niches of species sharing the same habitat or resources is fundamental to evaluate the mechanisms of coexistence or competition and eventually predict the consequences of ecosystem changes in the community.
Collapse
Affiliation(s)
- Ève Rioux
- Département de Biologie, Chimie et Géographie Centre for Northern Studies & Centre for Forest Research Université du Québec à Rimouski Rimouski Québec Canada
| | - Fanie Pelletier
- Département de biologie Centre for Northern Studies Université de Sherbrooke Sherbrooke Québec Canada
| | - Martin‐Hugues St‐Laurent
- Département de Biologie, Chimie et Géographie Centre for Northern Studies & Centre for Forest Research Université du Québec à Rimouski Rimouski Québec Canada
| |
Collapse
|
11
|
Páez YC, Betancourt CMA, Sansón GG, Kidd KA, Curry RA, Aceves DK. Mercury concentrations and stable isotopes (δ 15N and δ 13C) in fish muscle indicate human impacts in tropical coastal lagoons. MARINE POLLUTION BULLETIN 2022; 176:113454. [PMID: 35217423 DOI: 10.1016/j.marpolbul.2022.113454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 02/05/2022] [Accepted: 02/08/2022] [Indexed: 06/14/2023]
Abstract
Coastal lagoons are essential nursery habitats of many marine fishes, but they are often sites of intense human activities that impact water quality and potentially the fish using these habitats. We compared the variability in nutrient uptake (using δ15N and δ13C) and total mercury (THg) levels in juveniles and adults of three common species in two lagoons on the central Mexican coast of the Pacific Ocean during the wet and dry seasons. One of three species, Achirus mazatlanus had higher THg, δ15N, and δ13C levels in the lagoon with the greatest wastewater inputs (Barra de Navidad). Delta13C varied seasonally for all three species and THg was higher in the dry season for Lutjanus argentiventris and in males of A. mazatlanus. Our results demonstrate that mercury and stable isotopes can identify impacts of human activities on estuarine ichthyofauna and the importance of understanding seasonal and spatial variability of measures that could impact monitoring and predictions of impacts in these lagoons.
Collapse
Affiliation(s)
- Yureidy Cabrera Páez
- Department of Studies for Sustainable Development of Coastal Zone and Canadian Rivers Institute, University of Guadalajara, Gómez-Farías 82, San Patricio-Melaque, Cihuatlán 48980, Mexico
| | - Consuelo María Aguilar Betancourt
- Department of Studies for Sustainable Development of Coastal Zone and Canadian Rivers Institute, University of Guadalajara, Gómez-Farías 82, San Patricio-Melaque, Cihuatlán 48980, Mexico
| | - Gaspar González Sansón
- Department of Studies for Sustainable Development of Coastal Zone and Canadian Rivers Institute, University of Guadalajara, Gómez-Farías 82, San Patricio-Melaque, Cihuatlán 48980, Mexico
| | - Karen A Kidd
- Department of Biology & School of Earth, Environment and Society, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.
| | - R Allen Curry
- Canadian Rivers Institute, Biology, Forestry and Environmental Management, University of New Brunswick, Fredericton, NB E3B 5A3, Canada.
| | - Daniel Kosonoy Aceves
- Department of Studies for Sustainable Development of Coastal Zone and Canadian Rivers Institute, University of Guadalajara, Gómez-Farías 82, San Patricio-Melaque, Cihuatlán 48980, Mexico
| |
Collapse
|
12
|
DeSantis LRG, Pardi MI, Du A, Greshko MA, Yann LT, Hulbert RC, Louys J. Global long-term stability of individual dietary specialization in herbivorous mammals. Proc Biol Sci 2022; 289:20211839. [PMID: 35135353 PMCID: PMC8826132 DOI: 10.1098/rspb.2021.1839] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Dietary variation within species has important ecological and evolutionary implications. While theoreticians have debated the consequences of trait variance (including dietary specialization), empirical studies have yet to examine intraspecific dietary variability across the globe and through time. Here, we use new and published serial sampled δ13Cenamel values of herbivorous mammals from the Miocene to the present (318 individuals summarized, 4134 samples) to examine how dietary strategy (i.e. browser, mixed-feeder, grazer) affects individual isotopic variation. We find that almost all herbivores, regardless of dietary strategy, are composed of individual specialists. For example, Cormohipparion emsliei (Equidae) from the Pliocene of Florida (approx. 5 Ma) exhibits a δ13Cenamel range of 13.4‰, but all individuals sampled have δ13Cenamel ranges of less than or equal to 2‰ (mean = 1.1‰). Most notably, this pattern holds globally and through time, with almost all herbivorous mammal individuals exhibiting narrow δ13Cenamel ranges (less than or equal to 3‰), demonstrating that individuals are specialized and less representative of their overall species' dietary breadth. Individual specialization probably reduces intraspecific competition, increases carrying capacities, and may have stabilizing effects on species and communities over time. Individual specialization among species with both narrow and broad dietary niches is common over space and time-a phenomenon not previously well recognized or documented empirically.
Collapse
Affiliation(s)
- Larisa R G DeSantis
- Department of Biological Sciences, Vanderbilt University, 1210 BSB/MRBIII 465 21st Avenue S., Nashville, TN 37232, USA.,Department of Earth and Environmental Sciences, Vanderbilt University, 7th floor, Science and Engineering Building, 5726 Stevenson Center, Nashville, TN 37240, USA
| | - Melissa I Pardi
- Department of Earth and Environmental Sciences, Vanderbilt University, 7th floor, Science and Engineering Building, 5726 Stevenson Center, Nashville, TN 37240, USA.,Research and Collections Center, Illinois State Museum, 1011 E. Ash St., Springfield, IL 62703, USA
| | - Andrew Du
- Research and Collections Center, Illinois State Museum, 1011 E. Ash St., Springfield, IL 62703, USA
| | - Michael A Greshko
- Department of Biological Sciences, Vanderbilt University, 1210 BSB/MRBIII 465 21st Avenue S., Nashville, TN 37232, USA
| | - Lindsey T Yann
- Department of Earth and Environmental Sciences, Vanderbilt University, 7th floor, Science and Engineering Building, 5726 Stevenson Center, Nashville, TN 37240, USA.,Waco Mammoth National Monument, 6220 Steinbeck Bend Drive, Waco, TX 76708, USA
| | - Richard C Hulbert
- Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA
| | - Julien Louys
- Australian Research Centre for Human Evolution, Griffith University, Brisbane, Australia
| |
Collapse
|
13
|
Bernstein S, Ruiz-Cooley RI, Kudela R, Anderson CR, Dunkin R, Field JC. Stable isotope analysis reveals differences in domoic acid accumulation and feeding strategies of key vectors in a California hotspot for outbreaks. HARMFUL ALGAE 2021; 110:102117. [PMID: 34887000 DOI: 10.1016/j.hal.2021.102117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 09/20/2021] [Accepted: 09/22/2021] [Indexed: 06/13/2023]
Abstract
Given the effects of harmful algal blooms (HABs) on human and wildlife health, understanding how domoic acid (DA) is accumulated and transferred through food webs is critical for recognizing the most affected marine communities and predicting ecosystem effects. This study combines stable isotopes of carbon (δ13C) and nitrogen (δ15N) from bulk muscle tissue with DA measurements from viscera to identify the foraging strategies of important DA vectors and predators in Monterey Bay, CA. Tissue samples were collected from 27 species across three habitats in the summer of 2018 and 2019 (time periods without prominent HABs). Our results highlight an inshore-offshore variation in krill δ13C values and DA concentrations ([DA]; ppm) in anchovies indicating differences in coastal productivity and DA accumulation. The narrow overlapping isotopic niches between anchovies and sardines suggest similar diets and trophic positions, but striking differences in [DA] indicate a degree of specialization, thus, resource partitioning. In contrast, krill, market squid, and juvenile rockfish accumulated minimal DA and had comparatively broad isotopic niches, suggesting a lower capacity to serve as vectors because of potential differences in diet or feeding in isotopically distinct locations. Low [DA] in the liver of stranded sea lions and their generalist foraging tendencies limits our ability to use them as sentinels for DA outbreaks in a specific geographic area. Collectively, our results show that DA was produced a few kilometers from the coastline, and anchovies were the most powerful DA vector in coastal-pelagic zones (their DA loads exceeded the 20 ppm FDA regulatory limits for human consumption), while mussels did not contain detectable DA and only reflect in situ DA, δ13C, and δ15N values. Our study demonstrates the efficacy of combining multiple biogeochemical tracers to improve HAB monitoring efforts and identify the main routes of DA transfer across habitats and trophic levels.
Collapse
Affiliation(s)
- Sophie Bernstein
- Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA.
| | - Rocio I Ruiz-Cooley
- Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA; Departamento de Oceanografía Biológica, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, México.
| | - Raphael Kudela
- University of California-Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Clarissa R Anderson
- Scripps Institution of Oceanography/Southern California Coastal Ocean Observing System, University of California, San Diego, Scripps Institute of Oceanography, 8880 Biological Grade La Jolla, CA 92037, USA
| | - Robin Dunkin
- University of California-Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - John C Field
- National Oceanic and Atmospheric Administration, Fisheries Ecology Division, Southwest Fisheries Science Center 110 McAllister Way Road Santa Cruz, CA 95060, USA
| |
Collapse
|
14
|
Sheppard CE, Heaphy R, Cant MA, Marshall HH. Individual foraging specialization in group-living species. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.10.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
15
|
Attard MRG, Lewis A, Wroe S, Hughes C, Rogers TL. Whisker growth in Tasmanian devils (
Sarcophilus harrisii
) and applications for stable isotope studies. Ecosphere 2021. [DOI: 10.1002/ecs2.3846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Marie R. G. Attard
- Department of Biological Sciences Royal Holloway University of London Egham TW20 0EX UK
- Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences University of New South Wales Sydney New South Wales Australia
| | - Anna Lewis
- Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences University of New South Wales Sydney New South Wales Australia
- The Carnivore Conservancy Ulverstone Tasmania Australia
| | - Stephen Wroe
- Function, Evolution and Anatomy Research Laboratory School of Environmental and Rural Science University of New England Armidale New South Wales Australia
| | - Channing Hughes
- The Carnivore Conservancy Ulverstone Tasmania Australia
- School of Life and Environmental Sciences The University of Sydney Sydney New South Wales Australia
| | - Tracey L. Rogers
- Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences University of New South Wales Sydney New South Wales Australia
| |
Collapse
|
16
|
Page HM, Schamel J, Emery KA, Schooler NK, Dugan JE, Guglielmino A, Schroeder DM, Palmstrom L, Hubbard DM, Miller RJ. Diet of a threatened endemic fox reveals variation in sandy beach resource use on California Channel Islands. PLoS One 2021; 16:e0258919. [PMID: 34710148 PMCID: PMC8553077 DOI: 10.1371/journal.pone.0258919] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/07/2021] [Indexed: 11/29/2022] Open
Abstract
The coastal zone provides foraging opportunities for insular populations of terrestrial mammals, allowing for expanded habitat use, increased dietary breadth, and locally higher population densities. We examined the use of sandy beach resources by the threatened island fox (Urocyon littoralis) on the California Channel Islands using scat analysis, surveys of potential prey, beach habitat attributes, and stable isotope analysis. Consumption of beach invertebrates, primarily intertidal talitrid amphipods (Megalorchestia spp.) by island fox varied with abundance of these prey across sites. Distance-based linear modeling revealed that abundance of giant kelp (Macrocystis pyrifera) wrack, rather than beach physical attributes, explained the largest amount of variation in talitrid amphipod abundance and biomass across beaches. δ13C and δ15N values of fox whisker (vibrissae) segments suggested individualism in diet, with generally low δ13C and δ15N values of some foxes consistent with specializing on primarily terrestrial foods, contrasting with the higher isotope values of other individuals that suggested a sustained use of sandy beach resources, the importance of which varied over time. Abundant allochthonous marine resources on beaches, including inputs of giant kelp, may expand habitat use and diet breadth of the island fox, increasing population resilience during declines in terrestrial resources associated with climate variability and long-term climate change.
Collapse
Affiliation(s)
- Henry M. Page
- Marine Science Institute, University of California, Santa Barbara, California, United States of America
- * E-mail:
| | - Juliann Schamel
- Channel Islands National Park, Ventura, California, United States of America
| | - Kyle A. Emery
- Marine Science Institute, University of California, Santa Barbara, California, United States of America
| | - Nicholas K. Schooler
- Marine Science Institute, University of California, Santa Barbara, California, United States of America
| | - Jenifer E. Dugan
- Marine Science Institute, University of California, Santa Barbara, California, United States of America
| | - Angela Guglielmino
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, United States of America
| | - Donna M. Schroeder
- Bureau of Ocean Energy Management, Camarillo, California, United States of America
| | - Linnea Palmstrom
- Marine Science Institute, University of California, Santa Barbara, California, United States of America
| | - David M. Hubbard
- Marine Science Institute, University of California, Santa Barbara, California, United States of America
| | - Robert J. Miller
- Marine Science Institute, University of California, Santa Barbara, California, United States of America
| |
Collapse
|
17
|
Pereyra PER, Hallwass G, Poesch M, Silvano RAM. ‘Taking Fishers’ Knowledge to the Lab’: An Interdisciplinary Approach to Understand Fish Trophic Relationships in the Brazilian Amazon. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.723026] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Trophic levels can be applied to describe the ecological role of organisms in food webs and assess changes in ecosystems. Stable isotopes analysis can assist in the understanding of trophic interactions and use of food resources by aquatic organisms. The local ecological knowledge (LEK) of fishers can be an alternative to advance understanding about fish trophic interactions and to construct aquatic food webs, especially in regions lacking research capacity. The objectives of this study are: to calculate the trophic levels of six fish species important to fishing by combining data from stable isotopes analysis and fishers’ LEK in two clear water rivers (Tapajós and Tocantins) in the Brazilian Amazon; to compare the trophic levels of these fish between the two methods (stable isotopes analysis and LEK) and the two rivers; and to develop diagrams representing the trophic webs of the main fish prey and predators based on fisher’s LEK. The fish species studied were Pescada (Plagioscion squamosissimus), Tucunaré (Cichla pinima), Piranha (Serrasalmus rhombeus), Aracu (Leporinus fasciatus), Charuto (Hemiodus unimaculatus), and Jaraqui (Semaprochilodus spp.). A total of 98 interviews and 63 samples for stable isotopes analysis were carried out in both rivers. The average fish trophic levels did not differ between the stable isotopes analysis and the LEK in the Tapajós, nor in the Tocantins Rivers. The overall trophic level of the studied fish species obtained through the LEK did not differ from data obtained through the stable isotopes analysis in both rivers, except for the Aracu in the Tapajós River. The main food items consumed by the fish according to fishers’ LEK did agree with fish diets as described in the biological literature. Fishers provided useful information on fish predators and feeding habits of endangered species, such as river dolphin and river otter. Collaboration with fishers through LEK studies can be a viable approach to produce reliable data on fish trophic ecology to improve fisheries management and species conservation in tropical freshwater environments and other regions with data limitations.
Collapse
|
18
|
Manlick PJ, Maldonado K, Newsome SD. Competition shapes individual foraging and survival in a desert rodent ensemble. J Anim Ecol 2021; 90:2806-2818. [PMID: 34453850 DOI: 10.1111/1365-2656.13583] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 08/17/2021] [Indexed: 01/08/2023]
Abstract
Intraspecific variation, including individual diet variation, can structure populations and communities, but the causes and consequences of individual foraging strategies are often unclear. Interactions between competition and resources are thought to dictate foraging strategies (e.g. specialization vs. generalization), but classical paradigms such as optimal foraging and niche theory offer contrasting predictions for individual consumers. Furthermore, both paradigms assume that individual foraging strategies maximize fitness, yet this prediction is rarely tested. We used repeated stable isotope measurements (δ13 C, δ15 N; N = 3,509) and 6 years of capture-mark-recapture data to quantify the relationship between environmental variation, individual foraging and consumer fitness among four species of desert rodents. We tested the relative effects of intraspecific competition, interspecific competition, resource abundance and resource diversity on the foraging strategies of 349 individual animals, and then quantified apparent survival as function of individual foraging strategies. Consistent with niche theory, individuals contracted their trophic niches and increased foraging specialization in response to both intraspecific and interspecific competition, but this effect was offset by resource availability and individuals generalized when plant biomass was high. Nevertheless, individual specialists obtained no apparent fitness benefit from trophic niche contractions as the most specialized individuals exhibited a 10% reduction in monthly survival compared to the most generalized individuals. Ultimately, this resulted in annual survival probabilities nearly 4× higher for generalists compared to specialists. These results indicate that competition is the proximate driver of individual foraging strategies, and that diet-mediated fitness variation regulates population and community dynamics in stochastic resource environments. Furthermore, our findings show dietary generalism is a fitness maximizing strategy, suggesting that plastic foraging strategies may play a key role in species' ability to cope with environmental change.
Collapse
Affiliation(s)
- Philip J Manlick
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Karin Maldonado
- Departamento de Ciencias, Facultad de Artes Liberales, Universidad Adolfo Ibáñez, Peñalolén, Chile
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, USA
| |
Collapse
|
19
|
Slade E, McKechnie I, Salomon AK. Archaeological and Contemporary Evidence Indicates Low Sea Otter Prevalence on the Pacific Northwest Coast During the Late Holocene. Ecosystems 2021; 25:548-566. [PMID: 35509679 PMCID: PMC9016008 DOI: 10.1007/s10021-021-00671-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 06/15/2021] [Indexed: 11/29/2022]
Abstract
The historic extirpation and subsequent recovery of sea otters (Enhydra lutris) have profoundly changed coastal social-ecological systems across the northeastern Pacific. Today, the conservation status of sea otters is informed by estimates of population carrying capacity or growth rates independent of human impacts. However, archaeological and ethnographic evidence suggests that for millennia, complex hunting and management protocols by Indigenous communities limited sea otter abundance near human settlements to reduce the negative impacts of this keystone predator on shared shellfish prey. To assess relative sea otter prevalence in the Holocene, we compared the size structure of ancient California mussels (Mytilus californianus) from six archaeological sites in two regions on the Pacific Northwest Coast, to modern California mussels at locations with and without sea otters. We also quantified modern mussel size distributions from eight locations on the Central Coast of British Columbia, Canada, varying in sea otter occupation time. Comparisons of mussel size spectra revealed that ancient mussel size distributions are consistently more similar to modern size distributions at locations with a prolonged absence of sea otters. This indicates that late Holocene sea otters were maintained well below carrying capacity near human settlements as a result of human intervention. These findings illuminate the conditions under which sea otters and humans persisted over millennia prior to the Pacific maritime fur trade and raise important questions about contemporary conservation objectives for an iconic marine mammal and the social-ecological system in which it is embedded.
Collapse
Affiliation(s)
- Erin Slade
- School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia V5A 1S6 Canada
| | - Iain McKechnie
- Historical Ecology & Coastal Archaeology Laboratory, Department of Anthropology, University of Victoria, Cornett B246a, 3800 Finnerty Rd, Victoria, British Columbia V8P 5C2 Canada
- Hakai Institute, Heriot Bay, Quadra Island, British Columbia Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0 Canada
| | - Anne K. Salomon
- School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia V5A 1S6 Canada
| |
Collapse
|
20
|
Tinker MT, Bodkin JL, Bowen L, Ballachey B, Bentall G, Burdin A, Coletti H, Esslinger G, Hatfield BB, Kenner MC, Kloecker K, Konar B, Miles AK, Monson DH, Murray MJ, Weitzman BP, Estes JA. Sea otter population collapse in southwest Alaska: assessing ecological covariates, consequences, and causal factors. ECOL MONOGR 2021. [DOI: 10.1002/ecm.1472] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Martin Tim Tinker
- U.S. Geological Survey Western Ecological Research Center 2885 Mission St. Santa Cruz California 95060 USA
| | - James L. Bodkin
- U.S. Geological Survey Alaska Science Center 4210 University Dr. Anchorage Alaska 99508 USA
| | - Lizabeth Bowen
- U.S. Geological Survey Western Ecological Research Center 3020 State University Drive Sacramento California 95819 USA
| | - Brenda Ballachey
- U.S. Geological Survey Alaska Science Center 4210 University Dr. Anchorage Alaska 99508 USA
| | - Gena Bentall
- Sea Otter Savvy 1961 Main St. 199 Watsonville California 95076 USA
| | - Alexander Burdin
- Kamchatka Branch of Pacific Geographical Institute FED Russian Academy of Sciences Partizanskaya, 6 Petropavlovsk‐Kamchatsky 683000 Russia
| | - Heather Coletti
- Southwest Alaska Inventory and Monitoring Network National Park Service 4175 Geist Rd. Fairbanks Alaska 99709 USA
| | - George Esslinger
- U.S. Geological Survey Alaska Science Center 4210 University Dr. Anchorage Alaska 99508 USA
| | - Brian B. Hatfield
- U.S. Geological Survey Western Ecological Research Center 2885 Mission St. Santa Cruz California 95060 USA
| | - Michael C. Kenner
- U.S. Geological Survey Western Ecological Research Center 2885 Mission St. Santa Cruz California 95060 USA
| | - Kimberly Kloecker
- U.S. Geological Survey Alaska Science Center 4210 University Dr. Anchorage Alaska 99508 USA
| | - Brenda Konar
- College of Fisheries and Ocean Sciences University of Alaska Fairbanks PO Box 757220 Fairbanks Alaska 99775 USA
| | - A. Keith Miles
- U.S. Geological Survey Western Ecological Research Center 3020 State University Drive Sacramento California 95819 USA
| | - Daniel H. Monson
- U.S. Geological Survey Alaska Science Center 4210 University Dr. Anchorage Alaska 99508 USA
| | | | - Benjamin P. Weitzman
- U.S. Geological Survey Alaska Science Center 4210 University Dr. Anchorage Alaska 99508 USA
| | - James A. Estes
- Department of Ecology and Evolutionary Biology University of California 130 McAllister Way Santa Cruz California 95060 USA
| |
Collapse
|
21
|
Riverón S, Raoult V, Baylis AMM, Jones KA, Slip DJ, Harcourt RG. Pelagic and benthic ecosystems drive differences in population and individual specializations in marine predators. Oecologia 2021; 196:891-904. [PMID: 34173892 DOI: 10.1007/s00442-021-04974-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 06/13/2021] [Indexed: 11/24/2022]
Abstract
Individual specialization, which describes whether populations are comprised of dietary generalists or specialists, has profound ecological and evolutionary implications. However, few studies have quantified individual specialization within and between sympatric species that are functionally similar but have different foraging modes. We assessed the relationship between individual specialization, isotopic niche metrics and foraging behaviour of two marine predators with contrasting foraging modes: pelagic foraging female South American fur seals (Arctocephalus australis) and benthic foraging female southern sea lions (Otaria byronia). Stable isotope analysis of carbon and nitrogen was conducted along the length of adult female vibrissae to determine isotopic niche metrics and the degree of individual specialization. Vibrissae integrated time ranged between 1.1 and 5.5 years, depending on vibrissae length. We found limited overlap in dietary niche-space. Broader population niche sizes were associated with higher degrees of individual specialization, while narrower population niches with lower degrees of individual specialization. The degree of individual specialization was influenced by pelagic and benthic foraging modes. Specifically, South American fur seals, foraging in dynamic pelagic environments with abundant but similar prey, comprised specialist populations composed of generalist individuals. In contrast, benthic southern sea lions foraging in habitats with diverse but less abundant prey had more generalist populations composed of highly specialized individuals. We hypothesize that differences in specialization within and between populations were related to prey availability and habitat differences. Our study supports growing body of literature highlighting that individual specialization is a critical factor in shaping the ecological niche of higher marine predators.
Collapse
Affiliation(s)
- Sabrina Riverón
- Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2113, Australia.
| | - Vincent Raoult
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, Australia
| | - Alastair M M Baylis
- Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2113, Australia.,South Atlantic Environmental Research Institute, Stanley Cottage, PO Box 609, Stanley, FIQQ 1ZZ, Falkland Islands
| | - Kayleigh A Jones
- British Antarctic Survey, High Cross, Madingley Rd, Cambridge, CB3 0ET, UK.,University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - David J Slip
- Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2113, Australia.,Taronga Conservation Society Australia, Bradley's Head Road, Mosman, NSW, 2088, Australia
| | - Robert G Harcourt
- Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2113, Australia
| |
Collapse
|
22
|
Grant RA, Goss VGA. What can whiskers tell us about mammalian evolution, behaviour, and ecology? Mamm Rev 2021. [DOI: 10.1111/mam.12253] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Robyn A. Grant
- Department of Natural Sciences Manchester Metropolitan University John Dalton Building, Chester Street ManchesterM1 5GDUK
| | - Victor G. A. Goss
- School of Engineering London South Bank University Borough Road LondonSE1 0AAUK
| |
Collapse
|
23
|
Ruiz‐Cooley RI, Gerrodette T, Chivers SJ, Danil K. Cooperative feeding in common dolphins as suggested by ontogenetic patterns in δ
15
N bulk and amino acids. J Anim Ecol 2021; 90:1583-1595. [DOI: 10.1111/1365-2656.13478] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 03/09/2021] [Indexed: 01/08/2023]
Affiliation(s)
- Rocio I. Ruiz‐Cooley
- Departamento de Oceanografía Biológica Centro de Investigación Científica y de Educación Superior de Ensenada Ensenada Baja California México
- Moss Landing Marine Laboratories San Jose State University Moss Landing CA USA
| | - Tim Gerrodette
- Southwest Fisheries Science Center National Marine Fisheries ServiceNational Oceanic and Atmospheric Administration Fisheries La Jolla CA USA
| | - Susan J. Chivers
- Southwest Fisheries Science Center National Marine Fisheries ServiceNational Oceanic and Atmospheric Administration Fisheries La Jolla CA USA
| | - Kerri Danil
- Southwest Fisheries Science Center National Marine Fisheries ServiceNational Oceanic and Atmospheric Administration Fisheries La Jolla CA USA
| |
Collapse
|
24
|
Service CN, Ingram T, Reimchen TE, Darimont CT. Intrapopulation foraging niche variation between phenotypes and genotypes of Spirit bear populations. Ecol Evol 2021; 11:5025-5037. [PMID: 34025989 PMCID: PMC8131816 DOI: 10.1002/ece3.7276] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 12/23/2020] [Accepted: 01/09/2021] [Indexed: 11/07/2022] Open
Abstract
Foraging niche variation within a species can contribute to the maintenance of phenotypic diversity. The multiniche model posits that phenotypes occupying different niches can contribute to the maintenance of balanced polymorphisms. Using coastal populations of black bears (Ursus americanus kermodei) from British Columbia, Canada, we examined potential foraging niche divergence between phenotypes (black and white "Spirit" coat color) and between genotypes (black-coated homozygote and heterozygous). We applied the Bayesian multivariate models, with biotracers of diet (δ13C and δ15N) together comprising the response variable, to draw inference about foraging niche variation. Variance-covariance matrices from multivariate linear mixed-effect models were visualized as the Bayesian standard ellipses in δ13C and δ15N isotopic space to assess potential seasonal and annual niche variation between phenotypes and genotypes. We did not detect a difference in annual isotopic foraging niche area in comparisons between genotypes or phenotypes. Consistent with previous field experimental and isotopic analyses, however, we found that white phenotype Spirit bears were modestly more enriched in δ15N during the fall foraging season, though with our modest sample sizes these results were not significant. Although also not statistically significant, variation in isotopic niches between genotypes revealed that heterozygotes were moderately more enriched in δ13C along hair segments grown during fall foraging compared with black-coated homozygotes. To the extent to which the pattern of elevated δ15N and δ13C may signal the consumption of salmon (Oncorhynchus spp.), as well as the influence of salmon consumption on reproductive fitness, these results suggest that black-coated heterozygotes could have a minor selective advantage in the fall compared with black-coated homozygotes. More broadly, our multivariate approach, coupled with knowledge of genetic variation underlying a polymorphic trait, provides new insight into the potential role of a multiniche mechanism in maintaining this rare morph of conservation priority in Canada's Great Bear Rainforest and could offer new understanding into polymorphisms in other systems.
Collapse
Affiliation(s)
- Christina N. Service
- Department of GeographyUniversity of VictoriaVictoriaBCCanada
- Raincoast Conservation FoundationSidneyBCCanada
- Kitasoo Xai'xais Stewardship AuthorityKitasoo/Xai'xais First NationKlemtuBCCanada
| | - Travis Ingram
- Department of ZoologyUniversity of OtagoDunedinNew Zealand
| | | | - Chris T. Darimont
- Department of GeographyUniversity of VictoriaVictoriaBCCanada
- Raincoast Conservation FoundationSidneyBCCanada
| |
Collapse
|
25
|
Smith JG, Tomoleoni J, Staedler M, Lyon S, Fujii J, Tinker MT. Behavioral responses across a mosaic of ecosystem states restructure a sea otter-urchin trophic cascade. Proc Natl Acad Sci U S A 2021; 118:e2012493118. [PMID: 33836567 PMCID: PMC7980363 DOI: 10.1073/pnas.2012493118] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Consumer and predator foraging behavior can impart profound trait-mediated constraints on community regulation that scale up to influence the structure and stability of ecosystems. Here, we demonstrate how the behavioral response of an apex predator to changes in prey behavior and condition can dramatically alter the role and relative contribution of top-down forcing, depending on the spatial organization of ecosystem states. In 2014, a rapid and dramatic decline in the abundance of a mesopredator (Pycnopodia helianthoides) and primary producer (Macrocystis pyrifera) coincided with a fundamental change in purple sea urchin (Strongylocentrotus purpuratus) foraging behavior and condition, resulting in a spatial mosaic of kelp forests interspersed with patches of sea urchin barrens. We show that this mosaic of adjacent alternative ecosystem states led to an increase in the number of sea otters (Enhydra lutris nereis) specializing on urchin prey, a population-level increase in urchin consumption, and an increase in sea otter survivorship. We further show that the spatial distribution of sea otter foraging efforts for urchin prey was not directly linked to high prey density but rather was predicted by the distribution of energetically profitable prey. Therefore, we infer that spatially explicit sea otter foraging enhances the resistance of remnant forests to overgrazing but does not directly contribute to the resilience (recovery) of forests. These results highlight the role of consumer and predator trait-mediated responses to resource mosaics that are common throughout natural ecosystems and enhance understanding of reciprocal feedbacks between top-down and bottom-up forcing on the regional stability of ecosystems.
Collapse
Affiliation(s)
- Joshua G Smith
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060;
| | - Joseph Tomoleoni
- Santa Cruz Field Station, Western Ecological Research Center, US Geological Survey, Santa Cruz, CA 95060
| | - Michelle Staedler
- Department of Conservation Research, Monterey Bay Aquarium, Monterey, CA 93940
| | - Sophia Lyon
- Santa Cruz Field Station, Western Ecological Research Center, US Geological Survey, Santa Cruz, CA 95060
| | - Jessica Fujii
- Department of Conservation Research, Monterey Bay Aquarium, Monterey, CA 93940
| | - M Tim Tinker
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060
- Santa Cruz Field Station, Western Ecological Research Center, US Geological Survey, Santa Cruz, CA 95060
| |
Collapse
|
26
|
Kone DV, Tinker MT, Torres LG. Informing sea otter reintroduction through habitat and human interaction assessment. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Sea otters Enhydra lutris have been absent from Oregon, USA, following their extirpation over a century ago. Stakeholder groups and native tribes are advocating for reintroduction to restore historic populations. We investigated the potential for successful reintroduction by: (1) estimating expected equilibrium sea otter densities as a function of habitat variables to assess sea otter habitat in Oregon; and (2) spatially relating areas of high expected densities to human activities (e.g. fisheries, recreation, vessel activity, protected areas) to anticipate potential disturbance or fishery resource competition. We estimated that 4538 (1742-8976; 95% CI) sea otters could exist in Oregon, with higher expected abundance (N = 1551) and densities (x̄ = 2.45 km-2) within the southern region. Most core habitat areas (97%), representing clusters of high expected densities, overlapped with some form of human activity. While commercial shipping and tow lanes overlapped little (1%) with core habitat areas, recreational activities (58%) and fisheries (76%) had a higher degree of overlap, posing higher disturbance risk. We anticipate higher resource competition potential with the commercial red sea urchin fishery (67% of harvest areas) than the commercial Dungeness crab fishery (9% of high-catch crabbing grounds). Our study presents the first published carrying capacity estimate for sea otters in Oregon and can provide population recovery targets, focus attention on ecological and socioeconomic considerations, and help to inform a recovery plan for a resident sea otter population. Our findings suggest current available habitat may be sufficient to support a sea otter population, but resource managers may need to further investigate and consider whether current human activities might conflict with reestablishment in Oregon, if plans for a reintroduction continue.
Collapse
Affiliation(s)
- DV Kone
- College of Earth, Ocean, and Atmospheric Science, Marine Mammal Institute, Oregon State University, 2030 SE Marine Science Drive, Newport, OR 97365, USA
- California Ocean Science Trust, 1111 Broadway, Oakland, CA 94607, USA
| | - MT Tinker
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - LG Torres
- Department of Fisheries and Wildlife, Marine Mammal Institute, Oregon State University, 2030 SE Marine Science Drive, Newport, OR 97365, USA
| |
Collapse
|
27
|
Camargo NF, Reis GG, Camargo ACL, Nardoto GB, Kneitel JM, Vieira EM. Seasonal isotopic niche of a rodent: High between‐individual variation but no changes in individual niche width during the rich‐resource period. Biotropica 2021. [DOI: 10.1111/btp.12921] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Nícholas F. Camargo
- Departamento de Ecologia Instituto de Ciências Biológicas Universidade de Brasília Brasília DF Brazil
| | - Guilherme G. Reis
- Departamento de Ecologia Instituto de Ciências Biológicas Universidade de Brasília Brasília DF Brazil
| | - Anna Carla L. Camargo
- Departamento de Ecologia Instituto de Ciências Biológicas Universidade de Brasília Brasília DF Brazil
| | - Gabriela B. Nardoto
- Departamento de Ecologia Instituto de Ciências Biológicas Universidade de Brasília Brasília DF Brazil
| | - Jamie M. Kneitel
- Department of Biological Sciences California State University Sacramento CA USA
| | - Emerson M. Vieira
- Departamento de Ecologia Instituto de Ciências Biológicas Universidade de Brasília Brasília DF Brazil
| |
Collapse
|
28
|
Helms JA, Roeder KA, Ijelu SE, Ratcliff I, Haddad NM. Bioenergy landscapes drive trophic shifts in generalist ants. J Anim Ecol 2020; 90:738-750. [PMID: 33314089 DOI: 10.1111/1365-2656.13407] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 11/12/2020] [Indexed: 11/28/2022]
Abstract
Changes in trophic niche-the pathways through which an organism obtains energy and nutrients-are a fundamental way in which organisms respond to environmental conditions. But the capacity for species to alter their trophic niches in response to global change, and the ways they do so when able, remain largely unknown. Here we examine food webs in three long-term and large-scale experiments to test how resource availability and nutritional requirements interact to determine an organism's trophic niche in the context of one of the largest global trends in land use-the rise in bioenergy production. We use carbon and nitrogen stable isotope analyses to characterize arthropod food webs across three biofuel crops representing a gradient in plant resource richness (corn monocultures, fields dominated by native switchgrass and restored prairie), and to quantify changes in the trophic niche of a widespread generalist ant species across habitats. In doing so, we measure the effects of basal resource richness on food chain length, niche breadth and trophic position. We frame our results in the context of two hypotheses that explain variation in trophic niche-the niche variation hypothesis which emphasizes the importance of resource diversity and ecological opportunity, and the optimal diet hypothesis which emphasizes dietary constraints and the availability of optimal resources. Increasing plant richness lengthened food chains by 10%-20% compared to monocultures. Niche breadths of generalist ants did not vary with resource richness, suggesting they were limited by optimal diet requirements and constraints rather than by ecological opportunity. The ants instead responded to changes in plant richness by shifting their estimated trophic position. In resource-poor monocultures, the ants were top predators, sharing a trophic position with predatory spiders. In resource-rich environments, in contrast, the ants were omnivores, relying on a mix of animal prey and plant-based resources. In addition to highlighting novel ecosystem impacts of alternate bioenergy landscapes, our results suggest that niche breadth and trophic diversification depend more on the presence of optimal resources than on ecological opportunity alone.
Collapse
Affiliation(s)
- Jackson A Helms
- Kellogg Biological Station, Department of Integrative Biology, Michigan State University, Hickory Corners, MI, USA
| | - Karl A Roeder
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | | | | | - Nick M Haddad
- Kellogg Biological Station, Department of Integrative Biology, Michigan State University, Hickory Corners, MI, USA
| |
Collapse
|
29
|
Primary Sources and Food Web Structure of a Tropical Wetland with High Density of Mangrove Forest. WATER 2020. [DOI: 10.3390/w12113105] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The trophic ecology of wetlands with mangrove forests remains poorly understood. Through the use of stomach contents analysis, stable isotope signatures, and Bayesian mixing models, the food web of a tropical wetland in the gulf of California was investigated. Consumers had heterogeneous diets, omnivores were the most abundant species (47%), followed by planktivorous (21%), minor piscivores (10%), major piscivores (10%), macrobenthivores (9%), and herbivores (3%). The values of δ13C (from −12 to −29‰) and δ15N (from 4 to 24‰) showed a wide range of isotopic values of the consumers. Most of the species had a broad isotopic niche and there was a large diet overlap of species due to the exploitation of a common set of food resources. Five trophic levels were identified, with the weakfish (Cynoscion xanthulus) as the top predator of this system with detritus coming from the mangrove as the main source that supports the food chain. This highlights the importance of the mangrove forests to such ecosystems, because not only they are the most important primary food source, but also, they offer habitat to a large suite of fauna, which are important components of the trophic chain.
Collapse
|
30
|
Jesmer BR, Kauffman MJ, Murphy MA, Goheen JR. A test of the Niche Variation Hypothesis in a ruminant herbivore. J Anim Ecol 2020; 89:2825-2839. [PMID: 32961601 DOI: 10.1111/1365-2656.13351] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 09/14/2020] [Indexed: 11/28/2022]
Abstract
Despite the shared prediction that the width of a population's dietary niche expands as food becomes limiting, the Niche Variation Hypothesis (NVH) and Optimal Foraging Theory (OFT) offer contrasting views about how individuals alter diet selection when food is limited. Classical OFT predicts that dietary preferences do not change as food becomes limiting, so individuals expand their diets as they compensate for a lack of preferred foods. In contrast, the NVH predicts that among-individual variation in cognition, physiology or morphology create functional trade-offs in foraging efficiency, thereby causing individuals to specialize on different subsets of food as food becomes limiting. To evaluate (a) the predictions of the NVH and OFT and (b) evidence for physiological and cognitive-based functional trade-offs, we used DNA microsatellites and metabarcoding to quantify the diet, microbiome and genetic relatedness (a proxy for social learning) of 218 moose Alces alces across six populations that varied in their degree of food limitation. Consistent with both the NVH and OFT, dietary niche breadth increased with food limitation. Increased diet breadth of individuals-rather than increased diet specialization-was strongly correlated with both food limitation and dietary niche breadth of populations, indicating that moose foraged in accordance with OFT. Diets were not constrained by inheritance of the microbiome or inheritance of diet selection, offering support for the little-tested hypothesis that functional trade-offs in food use (or lack thereof) determine whether populations adhere to the predictions of the NVH or OFT. Our results indicate that both the absence of strong functional trade-offs and the digestive physiology of ruminants provide contexts under which populations should forage in accordance with OFT rather than the NVH. Also, because dietary niche width increased with increased food limitation, OFT and the NVH provide theoretical support for the notion that plant-herbivore interaction networks are plastic rather than static, which has important implications for understanding interspecific niche partitioning. Lastly, because population-level dietary niche breadth and calf recruitment are correlated, and because calf recruitment can be a proxy for food limitation, our work demonstrates how diet data can be employed to understand a populations' proximity to carrying capacity.
Collapse
Affiliation(s)
- Brett R Jesmer
- Program in Ecology, University of Wyoming, Laramie, WY, USA.,Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA.,Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA.,Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA.,Center for Biodiversity and Global Change, Yale University, New Haven, CT, USA
| | - Matthew J Kauffman
- Program in Ecology, University of Wyoming, Laramie, WY, USA.,Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA.,Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA.,U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | - Melanie A Murphy
- Program in Ecology, University of Wyoming, Laramie, WY, USA.,Department of Ecosystem Science and Management, University of Wyoming, Laramie, WY, USA
| | - Jacob R Goheen
- Program in Ecology, University of Wyoming, Laramie, WY, USA.,Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| |
Collapse
|
31
|
Carrasco TS, de Lima RC, Botta S, Machado R, Simões-Lopes PC, Ott PH, Secchi ER. Temporal and individual variation in the diet of the Neotropical otter, Lontra longicaudis (Olfers, 1818) (Carnivora, Mustelidae), as revealed by stable isotope analysis of vibrissae. Mamm Biol 2020. [DOI: 10.1007/s42991-020-00060-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
32
|
High Trophic Niche Overlap between a Native and Invasive Mink Does Not Drive Trophic Displacement of the Native Mink during an Invasion Process. Animals (Basel) 2020; 10:ani10081387. [PMID: 32785203 PMCID: PMC7460352 DOI: 10.3390/ani10081387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/03/2020] [Accepted: 08/06/2020] [Indexed: 11/23/2022] Open
Abstract
Simple Summary Invasive species are widely recognized to negatively affect native species through both direct and indirect interactions. When diet overlap between the native and invasive species increases, their competitive interaction is expected to increase too. This in turn may lead to displacement of one of the species. However, the specific mechanisms of the diet displacement are still unclear. In this study, we analysed the diet and diet overlap between the critically endangered European mink and the invasive American mink during the invasion process of the latter species by means of stable isotope analyses. We found a significant diet overlap between the native and invasive mink when they co-occur, an important individual variation of diet, and no significant change of diet of the native species in response to the arrival of the invasive mink. These results suggest significant competitive pressure imposed on the native European mink by the invasive American mink. As such, urgent implementation of control measures of invasive species is needed to ensure the viability and conservation of endangered European mink populations. Abstract The pressure elicited by invasive species on native species significantly increases with the increase of the overlap of their ecological niches. Still, the specific mechanisms of the trophic displacement of native species during the invasion process are unclear. The effects of the invasive American mink (Neovison vison) on the critically endangered European mink (Mustela lutreola) was assessed by analyses of diet and niche overlap during the invasion process. To do this, the isotopic composition (δ13C and δ15N) of both species of mink and their four main types of prey was analysed. Significant trophic overlap between the native European mink and invasive American mink was found when they coexisted in sympatry. Furthermore, both mink species were characterised by significant individual variation in diet and no obvious change in diet of the native species in response to the arrival of the introduced species was observed. High niche overlap registered between both species in sympatry with no displacement in diet of the native mink in response to the arrival of the invasive mink is expected to have important consequences for the viability and conservation of the native mink populations, as it suggests high competitive pressure.
Collapse
|
33
|
Scholz C, Firozpoor J, Kramer‐Schadt S, Gras P, Schulze C, Kimmig SE, Voigt CC, Ortmann S. Individual dietary specialization in a generalist predator: A stable isotope analysis of urban and rural red foxes. Ecol Evol 2020; 10:8855-8870. [PMID: 32884662 PMCID: PMC7452770 DOI: 10.1002/ece3.6584] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/17/2020] [Accepted: 06/22/2020] [Indexed: 11/09/2022] Open
Abstract
Some carnivores are known to survive well in urban habitats, yet the underlying behavioral tactics are poorly understood. One likely explanation for the success in urban habitats might be that carnivores are generalist consumers. However, urban populations of carnivores could as well consist of specialist feeders. Here, we compared the isotopic specialization of red foxes in urban and rural environments, using both a population and an individual level perspective. We measured stable isotope ratios in increments of red fox whiskers and potential food sources. Our results reveal that red foxes have a broad isotopic dietary niche and a large variation in resource use. Despite this large variation, we found significant differences between the variance of the urban and rural population for δ13C as well as δ15N values, suggesting a habitat-specific foraging behavior. Although urban regions are more heterogeneous regarding land cover (based on the Shannon index) than rural regions, the dietary range of urban foxes was smaller compared with that of rural conspecifics. Moreover, the higher δ13C values and lower δ15N values of urban foxes suggest a relatively high input of anthropogenic food sources. The diet of most individuals remained largely constant over a longer period. The low intraindividual variability of urban and rural red foxes suggests a relatively constant proportion of food items consumed by individuals. Urban and rural foxes utilized a small proportion of the potentially available isotopic dietary niche as indicated by the low within-individual variation compared to the between-individual variation. We conclude that generalist fox populations consist of individual food specialists in urban and rural populations at least over those periods covered by our study.
Collapse
Affiliation(s)
- Carolin Scholz
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| | - Jasmin Firozpoor
- Department of Evolutionary EcologyLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| | - Stephanie Kramer‐Schadt
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
- Institute of EcologyTechnische Universität BerlinBerlinGermany
- Berlin‐Brandenburg Institute of Advanced Biodiversity Research (BBIB)BerlinGermany
| | - Pierre Gras
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
- Berlin‐Brandenburg Institute of Advanced Biodiversity Research (BBIB)BerlinGermany
| | | | - Sophia E. Kimmig
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| | - Christian C. Voigt
- Department of Evolutionary EcologyLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
- Berlin‐Brandenburg Institute of Advanced Biodiversity Research (BBIB)BerlinGermany
- Institute of BiologyFreie Universität BerlinBerlinGermany
| | - Sylvia Ortmann
- Department of Evolutionary EcologyLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
- Berlin‐Brandenburg Institute of Advanced Biodiversity Research (BBIB)BerlinGermany
| |
Collapse
|
34
|
Pedrinho A, Mendes LW, Merloti LF, Andreote FD, Tsai SM. The natural recovery of soil microbial community and nitrogen functions after pasture abandonment in the Amazon region. FEMS Microbiol Ecol 2020; 96:5876346. [DOI: 10.1093/femsec/fiaa149] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 07/23/2020] [Indexed: 12/18/2022] Open
Abstract
ABSTRACT
We assessed the impacts of forest-to-pasture conversion on the dynamic of soil microbial communities, especially those involved in the N-cycle, and their potential functions, using DNA-metagenomic sequencing coupled with the quantification of marker genes for N-cycling. We also evaluated whether the community's dynamic was reestablished with secondary forest growth. In general, the microbial community structure was influenced by changes in soil chemical properties. Aluminum and nitrate significantly correlated to community structure and with 12 out of 21 microbial phyla. The N-related microbial groups and their potential functions were also affected by land-use change, with pasture being clearly different from primary and secondary forest systems. The microbial community analysis demonstrated that forest-to-pasture conversion increased the abundance of different microbial groups related to nitrogen fixation, including Bacteroidetes, Chloroflexi and Firmicutes. In contrast, after pasture abandonment and with the secondary forest regeneration, there was an increase in the abundance of Proteobacteria taxa and denitrification genes. Our multi-analytical approach indicated that the secondary forest presented some signs of resilience, suggesting that the N-related microbial groups and their potential functions can be recovered over time with implications for future ecological restoration programs.
Collapse
Affiliation(s)
- Alexandre Pedrinho
- Soil Microbiology Laboratory, Luiz de Queiroz College of Agriculture (ESALQ), University of Sao Paulo, Avenida Padua Dias 11, Piracicaba, Sao Paulo 13418-900, Brazil
- Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture (CENA), University of Sao Paulo, Avenida Centenario 303, Piracicaba, Sao Paulo 13416-000, Brazil
| | - Lucas William Mendes
- Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture (CENA), University of Sao Paulo, Avenida Centenario 303, Piracicaba, Sao Paulo 13416-000, Brazil
| | - Luis Fernando Merloti
- Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture (CENA), University of Sao Paulo, Avenida Centenario 303, Piracicaba, Sao Paulo 13416-000, Brazil
| | - Fernando Dini Andreote
- Soil Microbiology Laboratory, Luiz de Queiroz College of Agriculture (ESALQ), University of Sao Paulo, Avenida Padua Dias 11, Piracicaba, Sao Paulo 13418-900, Brazil
| | - Siu Mui Tsai
- Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture (CENA), University of Sao Paulo, Avenida Centenario 303, Piracicaba, Sao Paulo 13416-000, Brazil
| |
Collapse
|
35
|
Bell O, Jones ME, Ruiz‐Aravena M, Hamede RK, Bearhop S, McDonald RA. Age-related variation in the trophic characteristics of a marsupial carnivore, the Tasmanian devil Sarcophilus harrisii. Ecol Evol 2020; 10:7861-7871. [PMID: 32760570 PMCID: PMC7391331 DOI: 10.1002/ece3.6513] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/21/2020] [Accepted: 05/26/2020] [Indexed: 01/22/2023] Open
Abstract
Age-related changes in diet have implications for competitive interactions and for predator-prey dynamics, affecting individuals and groups at different life stages. To quantify patterns of variation and ontogenetic change in the diets of Tasmanian devils Sarcophilus harrisii, a threatened marsupial carnivore, we analyzed variation in the stable isotope composition of whisker tissue samples taken from 91 individual devils from Wilmot, Tasmania from December 2014 to February 2017. Both δ13C and δ15N decreased with increasing age in weaned Tasmanian devils, indicating that as they age devils rely less on small mammals and birds, and more on large herbivores. Devils <12 months old had broader group isotopic niches, as estimated by Bayesian standard ellipses (SEAB mode = 1.042) than devils from 12 to 23 months old (mode = 0.541) and devils ≥24 months old (mode = 0.532). Devils <24 months old had broader individual isotopic niches (SEAB mode range 0.492-1.083) than devils ≥24 months old (mode range 0.092-0.240). A decrease in δ15N from the older whisker sections to the more recently grown sections in devils <24 months old likely reflects the period of weaning in this species, as this pattern was not observed in devils ≥24 months old. Our data reveal changes in the isotopic composition of devil whiskers with increasing age, accompanied by a reduction in isotopic variation both among population age classes and within individuals, reflecting the effect of weaning in early life, and a likely shift from an initially diverse diet of small mammals, birds, and invertebrates towards increasing consumption of larger herbivores in adulthood.
Collapse
Affiliation(s)
- Olivia Bell
- Environment and Sustainability InstituteUniversity of ExeterPenrynUK
| | - Menna E. Jones
- School of Natural SciencesUniversity of TasmaniaHobartTas.Australia
| | - Manuel Ruiz‐Aravena
- School of Natural SciencesUniversity of TasmaniaHobartTas.Australia
- Department of Microbiology and ImmunologyMontana State UniversityBozemanMTUSA
| | | | - Stuart Bearhop
- Centre for Ecology and ConservationUniversity of ExeterPenrynUK
| | | |
Collapse
|
36
|
Rolla M, Consuegra S, Garcia de Leaniz C. Trophic Plasticity of the Highly Invasive Topmouth Gudgeon (Pseudorasbora parva) Inferred From Stable Isotope Analysis. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00212] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
37
|
O'Brien O, Allen S, Krützen M, Connor R. Alliance-specific habitat selection by male Indo-Pacific bottlenose dolphins in Shark Bay, Western Australia. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
|
38
|
Jordaan RK, Somers MJ, Hall G, McIntyre T. The diet of spotted-necked otters foraging in trout-stocked waters in Mpumalanga, South Africa. AFRICAN ZOOLOGY 2020. [DOI: 10.1080/15627020.2020.1741447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Rowan K Jordaan
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Michael J Somers
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
- Eugène Marais Chair of Wildlife Management, Centre for Invasion Biology, University of Pretoria, Pretoria, South Africa
| | - Grant Hall
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Trevor McIntyre
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
- Department of Life and Consumer Sciences, University of South Africa, Roodepoort, South Africa
| |
Collapse
|
39
|
Ellner SP, Ng WH, Myers CR. Individual Specialization and Multihost Epidemics: Disease Spread in Plant-Pollinator Networks. Am Nat 2020; 195:E118-E131. [PMID: 32364778 DOI: 10.1086/708272] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Many parasites infect multiple species and persist through a combination of within- and between-species transmission. Multispecies transmission networks are typically constructed at the species level, linking two species if any individuals of those species interact. However, generalist species often consist of specialized individuals that prefer different subsets of available resources, so individual- and species-level contact networks can differ systematically. To explore the epidemiological impacts of host specialization, we build and study a model for pollinator pathogens on plant-pollinator networks, in which individual pollinators have dynamic preferences for different flower species. We find that modeling and analysis that ignore individual host specialization can predict die-off of a disease that is actually strongly persistent and can badly over- or underpredict steady-state disease prevalence. Effects of individual preferences remain substantial whenever mean preference duration exceeds half of the mean time from infection to recovery or death. Similar results hold in a model where hosts foraging in different habitats have different frequencies of contact with an environmental reservoir for the pathogen. Thus, even if all hosts have the same long-run average behavior, dynamic individual differences can profoundly affect disease persistence and prevalence.
Collapse
|
40
|
Elliott Smith EA, Tinker MT, Whistler EL, Kennett DJ, Vellanoweth RL, Gifford‐Gonzalez D, Hylkema MG, Newsome SD. Reductions in the dietary niche of southern sea otters ( Enhydra lutris nereis) from the Holocene to the Anthropocene. Ecol Evol 2020; 10:3318-3329. [PMID: 32273989 PMCID: PMC7141068 DOI: 10.1002/ece3.6114] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 01/17/2020] [Accepted: 01/20/2020] [Indexed: 12/04/2022] Open
Abstract
The sea otter (Enhydra lutris) is a marine mammal hunted to near extinction during the 1800s. Despite their well-known modern importance as a keystone species, we know little about historical sea otter ecology. Here, we characterize the ecological niche of ancient southern sea otters (E. lutris nereis) using δ13C analysis and δ15N analysis of bones recovered from archaeological sites spanning ~7,000 to 350 years before present (N = 112 individuals) at five regions along the coast of California. These data are compared with previously published data on modern animals (N = 165) and potential modern prey items. In addition, we analyze the δ15N of individual amino acids for 23 individuals to test for differences in sea otter trophic ecology through time. After correcting for tissue-specific and temporal isotopic effects, we employ nonparametric statistics and Bayesian niche models to quantify differences among ancient and modern animals. We find ancient otters occupied a larger isotopic niche than nearly all modern localities; likely reflecting broader habitat and prey use in prefur trade populations. In addition, ancient sea otters at the most southerly sites occupied an isotopic niche that was more than twice as large as ancient otters from northerly regions. This likely reflects greater invertebrate prey diversity in southern California relative to northern California. Thus, we suggest the potential dietary niche of sea otters in southern California could be larger than in central and northern California. At two sites, Año Nuevo and Monterey Bay, ancient otters had significantly higher δ15N values than modern populations. Amino acid δ15N data indicated this resulted from shifting baseline isotope values, rather than a change in sea otter trophic ecology. Our results help in better understanding the contemporary ecological role of sea otters and exemplify the strength of combing zooarchaeological and biological information to provide baseline data for conservation efforts.
Collapse
Affiliation(s)
| | - Martin Tim Tinker
- Nhydra Ecological ConsultingSt Margaret’s BayNova ScotiaCanada
- Department of Ecology and Evolutionary BiologyUniversity of California Santa CruzSanta CruzCAUSA
| | | | | | - René L. Vellanoweth
- Department of AnthropologyCalifornia State University Los AngelesLos AngelesCAUSA
| | | | - Mark G. Hylkema
- California Department of Parks and RecreationSanta CruzCAUSA
| | - Seth D. Newsome
- Department of BiologyUniversity of New MexicoAlbuquerqueNMUSA
| |
Collapse
|
41
|
Effects of urbanization on resource use and individual specialization in coyotes (Canis latrans) in southern California. PLoS One 2020; 15:e0228881. [PMID: 32023321 PMCID: PMC7001990 DOI: 10.1371/journal.pone.0228881] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 01/24/2020] [Indexed: 11/30/2022] Open
Abstract
Urban environments are unique because fragments of natural or semi-natural habitat are embedded within a potentially permeable matrix of human-dominated areas, creating increased landscape and, potentially, habitat heterogeneity. In addition, urban areas can provide diet subsidies for wildlife species in the form of fruiting ornamental plants, trash, and domestic animals. Ecological opportunity in the forms of habitat and food heterogeneity are thought to be important mechanisms in maintaining individual specialization. Identifying which contexts, traits, and mechanisms determine the success or failure of individuals within an urban wildlife population could potentially provide predictions about which populations may succeed in human-dominated landscapes and which may experience local extinction. We used both scat and stable isotope analysis of whiskers to investigate the degree to which coyotes (Canis latrans) utilized anthropogenic subsidies and exhibited individual diet specialization across the urban-rural gradient in southern California. Land use surrounding scat and isotope sample locations was also evaluated to determine the effect of land cover on diet. Human food constituted a significant portion of urban coyote diet (22% of scats, 38% of diet estimated by stable isotope analysis). Domestic cats (Felis catus) and ornamental fruit and seeds were also important items in urban coyote diets. Consumption of anthropogenic items decreased with decreasing urbanization. In suburban areas, seasonality influenced the frequency of occurrence of anthropogenic subsidies with increased consumption in the dry season. The amount of altered open space (areas such as golf courses, cemeteries, and landscaped parks) nearby had a negative effect on the consumption of anthropogenic items in both urban and suburban areas. Contrary to our hypothesis, urban coyotes displayed reduced between-individual variation compared to suburban and rural coyotes. It is possible that the core urban areas of cities are so densely developed and subsidized that wildlife inhabiting these areas actually have reduced ecological opportunity. Suburban animals had the broadest isotopic niches and maintained similar individual specialization to rural coyotes. Wildlife in suburban areas still have access to relatively undisturbed natural areas while being able to take advantage of anthropogenic subsidies in neighboring residential areas. Therefore, areas with intermediate urban development may be associated with increased ecological opportunity and specialization.
Collapse
|
42
|
Eckrich CA, Albeke SE, Flaherty EA, Bowyer RT, Ben‐David M. rKIN: Kernel‐based method for estimating isotopic niche size and overlap. J Anim Ecol 2020; 89:757-771. [DOI: 10.1111/1365-2656.13159] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 10/11/2019] [Indexed: 11/28/2022]
Affiliation(s)
| | - Shannon E. Albeke
- Wyoming Geographic Information Science Center University of Wyoming Laramie WY USA
- Program in Ecology University of Wyoming Laramie WY USA
| | - Elizabeth A. Flaherty
- Department of Forestry and Natural Resources Purdue University West Lafayette IN USA
| | - R. Terry Bowyer
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks AK USA
| | - Merav Ben‐David
- Program in Ecology University of Wyoming Laramie WY USA
- Department of Zoology and Physiology University of Wyoming Laramie WY USA
| |
Collapse
|
43
|
Juárez-Rodríguez M, Heckel G, Herguera-García JC, Elorriaga-Verplancken FR, Herzka SZ, Schramm Y. Trophic ecology of Mexican Pacific harbor seal colonies using carbon and nitrogen stable isotopes. PLoS One 2020; 15:e0225889. [PMID: 31967988 PMCID: PMC6975529 DOI: 10.1371/journal.pone.0225889] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 11/14/2019] [Indexed: 11/28/2022] Open
Abstract
There is limited information that provides a comprehensive understanding of the trophic ecology of Mexican Pacific harbor seal (Phoca vitulina richardii) colonies. While scat analysis has been used to determine the diet of some colonies, the integrative characterization of its feeding habits on broader temporal and spatial scales remains limited. We examined potential feeding grounds, trophic niche width, and overlap, and inferred the degree of dietary specialization using stable carbon and nitrogen isotope ratios (δ13C and δ15N) in this subspecies. We analyzed δ13C and δ15N on fur samples from pups collected at five sites along the western coast of the Baja California Peninsula, Mexico. Fur of natal coat of Pacific harbor seal pups begins to grow during the seventh month in utero until the last stage of gestation. Therefore pup fur is a good proxy for the mother's feeding habits in winter (~December to March), based on the timing of gestation for the subspecies in this region. Our results indicated that the δ13C and δ15N values differed significantly among sampling sites, with the highest mean δ15N value occurring at the southernmost site, reflecting a well-characterized north to south latitudinal 15N-enrichment in the food web. The tendency identified in δ13C values, in which the northern colonies showed the most enriched values, suggests nearshore and benthic-demersal feeding habits. A low variance in δ13C and δ15N values for each colony (<1‰) and relatively small standard ellipse areas suggest a specialized foraging behavior in adult female Pacific harbor seals in Mexican waters.
Collapse
Affiliation(s)
- Maricela Juárez-Rodríguez
- Departamento de Biología de la Conservación, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, México
| | - Gisela Heckel
- Departamento de Biología de la Conservación, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, México
| | - Juan Carlos Herguera-García
- Departamento de Ecología Marina, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, México
| | - Fernando R. Elorriaga-Verplancken
- Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, Departamento de Pesquerías y Biología Marina, La Paz, Baja California Sur, México
| | - Sharon Z. Herzka
- Departamento de Oceanografía Biológica, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, México
| | - Yolanda Schramm
- Facultad de Ciencias Marinas, Universidad Autónoma de Baja California, Ensenada, Baja California, México
| |
Collapse
|
44
|
Mozzon CM, Lescord GL, Savage PL, Johnston TA. The trophic niche of sculpins Cottus spp. in forage fish assemblages of boreal lakes. JOURNAL OF FISH BIOLOGY 2020; 96:92-101. [PMID: 31661158 DOI: 10.1111/jfb.14188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/16/2019] [Indexed: 06/10/2023]
Abstract
We compared the trophic niches of freshwater sculpins Cottus spp. with those of other co-habiting forage fishes in two groups of boreal lakes with distinct habitats and fish communities. Near North Lakes (45° 00' to 47° 30' N) were deeper, stratified and contained lake trout Salvelinus namaycush as the apex piscivore, whereas Far North Lakes (51° 10' to 52° 20' N) were shallower, did not stratify and contained pike Esox lucius and walleye Sander vitreus as the apex piscivores. Trophic niches of sculpins and other forage fishes were compared based on niche metrics calculated from muscle stable carbon (δ13 C) and nitrogen (δ15 N) isotope ratios. In Near North Lakes, sculpins were found almost exclusively in deep, offshore waters and their niche positions reflected a greater reliance on pelagic production (lower δ13 C) and a higher trophic elevation (higher δ15 N) compared with most other forage fishes. Furthermore, sculpins in Near North Lakes tended to have larger trophic niches (occupied greater area in δ13 C- δ15 N space), particularly in the food chain (δ15 N) dimension, than other cohabiting forage fishes. In contrast, sculpins in Far North Lakes were commonly found in the nearshore and had trophic niche positions and sizes that were similar to those of the other cohabiting forage fishes. This study illustrates the flexibility in the realised trophic niches of sculpins in relation to habitat availability and fish community composition in boreal lakes.
Collapse
Affiliation(s)
- Christina M Mozzon
- Biology Department, Cooperative Freshwater Ecology Unit, Laurentian University, Sudbury, Ontario, Canada
| | - Gretchen L Lescord
- Biology Department, Cooperative Freshwater Ecology Unit, Laurentian University, Sudbury, Ontario, Canada
| | - Pascale-Laure Savage
- Biology Department, Cooperative Freshwater Ecology Unit, Laurentian University, Sudbury, Ontario, Canada
| | - Thomas A Johnston
- Ontario Ministry of Natural Resources and Forestry, Cooperative Freshwater Ecology Unit, Laurentian University, Sudbury, Ontario, Canada
| |
Collapse
|
45
|
Stanek A, Wolf N, Welker J, Jensen S. Experimentally derived incorporation rates and diet-to-tissue discrimination values for carbon and nitrogen stable isotopes in gray wolves (Canis lupus) fed a marine diet. CAN J ZOOL 2019. [DOI: 10.1139/cjz-2019-0049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent studies have noted the differential effects of marine versus terrestrial diets on the carbon and nitrogen stable isotope (13C and 15N, respectively) diet-to-tissue discrimination values and incorporation rates for omnivorous and carnivorous mammals. Inaccurate estimates of these parameters may result in misrepresentation of diet composition or in the timing of diet shifts. Here, we present the results of a diet-switch experiment designed to estimate diet-to-tissue discrimination values and incorporation rates for tissues of gray wolves (Canis lupus Linnaeus, 1758) fed a diet of Pacific salmon (genus Oncorhynchus Suckley, 1861). Our results demonstrate substantial differences in both parameters between wolves maintained on a marine (salmon) diet and wolves maintained on terrestrially sourced prey (beef, Bos taurus Linnaeus, 1758). Increased awareness of the significance of marine resources to omnivorous and carnivorous consumers, like wolves, highlights the importance of phenomenological and mechanistic understandings of the effects of fish and other marine prey on dietary investigations based on stable isotopes.
Collapse
Affiliation(s)
- A.E. Stanek
- Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, AK 99508, USA
| | - N. Wolf
- Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, AK 99508, USA
| | - J.M. Welker
- Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, AK 99508, USA
- Ecology and Genetics Research Unit, University of Oulu, Finland 90014, and UArctic Research Chair
| | - S. Jensen
- The Alaska Zoo, 4731 O’Malley Road, Anchorage, AK 99507, USA
| |
Collapse
|
46
|
Harley JR, Gill VA, Lee S, Kannan K, Santana V, Burek-Huntington K, O'Hara TM. Concentrations of organohalogens (PCBs, DDTs, PBDEs) in hunted and stranded Northern sea otters (Enhydra lutris kenyoni) in Alaska from 1992 to 2010: Links to pathology and feeding ecology. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 691:789-798. [PMID: 31326802 PMCID: PMC6711818 DOI: 10.1016/j.scitotenv.2019.07.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 06/10/2023]
Abstract
Many organohalogen compounds (OHCs) are persistent organic pollutants (POPs) found in appreciable concentrations in marine predators. While production of some POPs has declined or ceased in recent decades, their capacity for global transport and bioaccumulation results in observations of unchanging or increasing concentrations in marine systems. Sea otters (Enhydra lutris) have been advocated as an environmental sentinel for contaminants due to their longevity, site fidelity and prey species that often overlap with human consumption. Using archived (1992-2010) samples of livers from Northern sea otters (n = 50) from Alaska we examine concentrations of chlordanes (CHLs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDTs), and polybrominated diphenyl ethers (PBDEs) and associated metabolites. We found some evidence for declining ΣPCBs over the two decades, however for most animals concentrations were low compared to toxicological thresholds. Six animals had relatively high concentrations of ΣPCBs (mean = 262,000 ng/g lipid weight), ΣDDTs (mean = 8,800 ng/g lw), and ΣPBDEs (mean = 4,600 ng/g lw), with four of these six animals experiencing hepatic parasitism or hepatitis. In order to assess whether differences in POP concentrations are associated with feeding ecology, we examined stable isotopes of C and N in archived muscle and whisker samples. In general, there were no significant relationships between ΣPOP concentrations and stable isotope ratios. There were small differences in stable isotope profiles in animals with high POP concentrations, although it was unclear if these differences were due to feeding ecology or disease processes. This study highlights the importance of considering feeding ecology and necropsy (health and disease status) data while conducting contaminant surveys, and confirms some previous reports of trends in OHCs in Alaska marine mammals.
Collapse
Affiliation(s)
- John R Harley
- Alaska Coastal Rainforest Center, University of Alaska Southeast, 11066 Auke Lake Way, Juneau, AK 99801, USA.
| | - Verena A Gill
- United States Fish and Wildlife Service, Marine Mammals Management, 1011 East Tudor Road, MS 341, Anchorage, AK 99503, USA; National Oceanic and Atmospheric Administration Fisheries, 222 W. 7th Ave, Rm 552, Anchorage, AK 99513, USA
| | - Sunmi Lee
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA; School of Public Health, State University of New York, Albany, NY 12201, USA
| | - Kurunthachalam Kannan
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA; School of Public Health, State University of New York, Albany, NY 12201, USA
| | - Vanessa Santana
- Department of Biology and Wildlife, University of Alaska, Fairbanks, 982 Koyukuk Dr, Fairbanks, AK 99775-7750, USA
| | - Kathy Burek-Huntington
- Alaska Veterinary Pathology Services, 23834 The Clearing Drive, Eagle River, AK 99577, USA
| | - Todd M O'Hara
- Department of Veterinary Medicine, University of Alaska, Fairbanks, 901 Koyukuk Dr, Fairbanks, AK 99775-7750, USA
| |
Collapse
|
47
|
Hostert LE, Pintor LM, Byers JE. Sex, size, and prey caloric value affect diet specialization and consumption of an invasive prey by a native predator. Curr Zool 2019; 65:499-507. [PMID: 31616480 PMCID: PMC6784505 DOI: 10.1093/cz/zoy076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 09/07/2018] [Indexed: 11/13/2022] Open
Abstract
Escaping the control of natural enemies is thought to heavily influence the establishment success and impact of non-native species. Here, we examined how the profitability of alternative prey in combination with the presence of a competitor and predator aggressive behavior explain individual differences in diet specialization and the consumption of the invasive green porcelain crab Petrolisthes armatus by the native mud crab predator Panopeus herbstii. Results from bomb calorimetry estimates show that invasive P. armatus has high caloric value relative to alternative native prey. Laboratory assays indicated that specialization and consumption of invasive P. armatus was mostly exhibited by large, female P. herbstii, but the presence of a competitor and predator aggressiveness did not influence diet and the consumption of P. armatus. Thus, intrinsic factors (e.g., sex and body size) seem to explain consumption of P. armatus and dietary specialization in P. herbstii, more generally. Although there are still many predator individuals that do not consume P. armatus, the proportion of individuals that have begun to specialize on P. armatus suggests that for some, it has become more profitable relative to alternative native prey. Given the high caloric value of P. armatus, we suggest that it is likely that differences in the cost of its consumption, including attack, capture, and handling times relative to alternative prey, determine its net profitability to individual predators.
Collapse
Affiliation(s)
- Lauren E Hostert
- School of Environment and Natural Resources, The Ohio State University, Columbus, OH, USA
| | - Lauren M Pintor
- School of Environment and Natural Resources, The Ohio State University, Columbus, OH, USA
| | - James E Byers
- Odum School of Ecology, University of Georgia, Athens, GA, USA
| |
Collapse
|
48
|
Jordaan RK, Somers MJ, Hall G, McIntyre T. Plasticity and specialisation in the isotopic niche of African clawless otters foraging in marine and freshwater habitats. Mamm Biol 2019. [DOI: 10.1016/j.mambio.2019.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
49
|
Affiliation(s)
- Thomas E Tomasi
- Department of Biology, Missouri State University, Springfield, MO, USA
| | - Briana N Anderson
- Department of Biology, Missouri State University, Springfield, MO, USA
| | - Theodore Garland
- Department of Evolution, Ecology, and Organismal Biology, University of California – Riverside, Riverside, CA, USA
| |
Collapse
|
50
|
Guscelli E, Spicer JI, Calosi P. The importance of inter-individual variation in predicting species' responses to global change drivers. Ecol Evol 2019; 9:4327-4339. [PMID: 31031908 PMCID: PMC6476784 DOI: 10.1002/ece3.4810] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 04/10/2018] [Accepted: 06/15/2018] [Indexed: 11/30/2022] Open
Abstract
Inter-individual variation in phenotypic traits has long been considered as "noise" rather than meaningful phenotypic variation, with biological studies almost exclusively generating and reporting average responses for populations and species' average responses. Here, we compare the use of an individual approach in the investigation of extracellular acid-base regulation by the purple sea urchin Paracentrotus lividus challenged with elevated pCO2 and temperature conditions, with a more traditional approach which generates and formally compares mean values. We detected a high level of inter-individual variation in acid-base regulation parameters both within and between treatments. Comparing individual and mean values for the first (apparent) dissociation constant of the coelomic fluid for individual sea urchins resulted in substantially different (calculated) acid-base parameters, and models with stronger statistical support. While the approach using means showed that coelomic pCO2 was influenced by seawater pCO2 and temperature combined, the individual approach indicated that it was in fact seawater temperature in isolation that had a significant effect on coelomic pCO2. On the other hand, coelomic [HCO3 -] appeared to be primarily affected by seawater pCO2, and less by seawater temperature, irrespective of the approach adopted. As a consequence, we suggest that individual variation in physiological traits needs to be considered, and where appropriate taken into account, in global change biology studies. It could be argued that an approach reliant on mean values is a "procedural error." It produces an artefact, that is, a population's mean phenotype. While this may allow us to conduct relatively simple statistical analyses, it will not in all cases reflect, or take into account, the degree of (physiological) diversity present in natural populations.
Collapse
Affiliation(s)
- Ella Guscelli
- Département de Biologie, Chimie et GéographieUniversité du Québec à RimouskiRimouskiQuébecCanada
- Marine Biology and Ecology Research Centre, School of Biological and Marine SciencesUniversity of PlymouthPlymouthUK
| | - John I. Spicer
- Marine Biology and Ecology Research Centre, School of Biological and Marine SciencesUniversity of PlymouthPlymouthUK
| | - Piero Calosi
- Département de Biologie, Chimie et GéographieUniversité du Québec à RimouskiRimouskiQuébecCanada
- Marine Biology and Ecology Research Centre, School of Biological and Marine SciencesUniversity of PlymouthPlymouthUK
| |
Collapse
|