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He F, Svenning JC, Chen X, Tockner K, Kuemmerle T, le Roux E, Moleón M, Gessner J, Jähnig SC. Freshwater megafauna shape ecosystems and facilitate restoration. Biol Rev Camb Philos Soc 2024. [PMID: 38411930 DOI: 10.1111/brv.13062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 01/31/2024] [Accepted: 02/02/2024] [Indexed: 02/28/2024]
Abstract
Freshwater megafauna, such as sturgeons, giant catfishes, river dolphins, hippopotami, crocodylians, large turtles, and giant salamanders, have experienced severe population declines and range contractions worldwide. Although there is an increasing number of studies investigating the causes of megafauna losses in fresh waters, little attention has been paid to synthesising the impacts of megafauna on the abiotic environment and other organisms in freshwater ecosystems, and hence the consequences of losing these species. This limited understanding may impede the development of policies and actions for their conservation and restoration. In this review, we synthesise how megafauna shape ecological processes in freshwater ecosystems and discuss their potential for enhancing ecosystem restoration. Through activities such as movement, burrowing, and dam and nest building, megafauna have a profound influence on the extent of water bodies, flow dynamics, and the physical structure of shorelines and substrata, increasing habitat heterogeneity. They enhance nutrient cycling within fresh waters, and cross-ecosystem flows of material, through foraging and reproduction activities. Freshwater megafauna are highly connected to other freshwater organisms via direct consumption of species at different trophic levels, indirect trophic cascades, and through their influence on habitat structure. The literature documenting the ecological impacts of freshwater megafauna is not evenly distributed among species, regions, and types of ecological impacts, with a lack of quantitative evidence for large fish, crocodylians, and turtles in the Global South and their impacts on nutrient flows and food-web structure. In addition, population decline, range contraction, and the loss of large individuals have reduced the extent and magnitude of megafaunal impacts in freshwater ecosystems, rendering a posteriori evaluation more difficult. We propose that reinstating freshwater megafauna populations holds the potential for restoring key ecological processes such as disturbances, trophic cascades, and species dispersal, which will, in turn, promote overall biodiversity and enhance nature's contributions to people. Challenges for restoration actions include the shifting baseline syndrome, potential human-megafauna competition for habitats and resources, damage to property, and risk to human life. The current lack of historical baselines for natural distributions and population sizes of freshwater megafauna, their life history, trophic interactions with other freshwater species, and interactions with humans necessitates further investigation. Addressing these knowledge gaps will improve our understanding of the ecological roles of freshwater megafauna and support their full potential for facilitating the development of effective conservation and restoration strategies to achieve the coexistence of humans and megafauna.
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Affiliation(s)
- Fengzhi He
- Key Laboratory of Wetland Ecology and Environment, State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Shengbei Street 4888, Changchun, 130102, China
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, Berlin, 12587, Germany
- Geography Department, Humboldt-Universität zu Berlin, Unter den Linden 6, Berlin, 10099, Germany
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) and Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Ny Munkegade 114, Aarhus, 8000, Denmark
| | - Jens-Christian Svenning
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) and Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Ny Munkegade 114, Aarhus, 8000, Denmark
| | - Xing Chen
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, Berlin, 12587, Germany
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Str. 1-3, Berlin, 14195, Germany
| | - Klement Tockner
- Senckenberg Society for Nature Research, Senckenberganlage 25, Frankfurt am Main, 60325, Germany
- Faculty for Biological Sciences, Goethe University Frankfurt, Max-von-Laue-Straße 9, Frankfurt am Main, 60438, Germany
| | - Tobias Kuemmerle
- Geography Department, Humboldt-Universität zu Berlin, Unter den Linden 6, Berlin, 10099, Germany
| | - Elizabeth le Roux
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) and Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Ny Munkegade 114, Aarhus, 8000, Denmark
| | - Marcos Moleón
- Department of Zoology, University of Granada, Avenida de Fuente Nueva S/N, Granada, 18071, Spain
| | - Jörn Gessner
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, Berlin, 12587, Germany
| | - Sonja C Jähnig
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, Berlin, 12587, Germany
- Geography Department, Humboldt-Universität zu Berlin, Unter den Linden 6, Berlin, 10099, Germany
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Senzaki M, Ando H, Kadoya T. Noise pollution alters the diet composition of invertebrate consumers both in and beyond a noise-exposed grassland ecosystem. Ecol Lett 2024; 27:e14323. [PMID: 37830457 DOI: 10.1111/ele.14323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/14/2023] [Accepted: 09/25/2023] [Indexed: 10/14/2023]
Abstract
Anthropogenic noise is ubiquitous globally. However, we know little about how the impacts of noise alter fundamental ecosystem properties, such as resource consumption by invertebrate consumers. Using experimental noise manipulation and faecal DNA metabarcoding, we assessed how the direct and cross-trophic indirect effects of noise altered the dietary richness and specializations of omnivorous grasshoppers in a grassland ecosystem. We found that the experimental noise treatment expanded grasshoppers' dietary richness and resulted in dietary generalizations in both noise-exposed and adjacent relatively quieter areas. Unexpectedly, however, these dietary changes were primarily explained by the direct effect of noise not only in the noise-exposed areas but also in the adjacent quieter areas and were relaxed by indirect effects of noise such as reduced birds and predation risk and increased grasshoppers. Our work suggests that noise pollution can be key in explaining the variation of invertebrate consumers' diets across a gradient of noise-exposed environments.
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Affiliation(s)
- Masayuki Senzaki
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba City, Ibaraki, Japan
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Haruko Ando
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba City, Ibaraki, Japan
| | - Taku Kadoya
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba City, Ibaraki, Japan
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Remili A, Dietz R, Sonne C, Samarra FIP, Letcher RJ, Rikardsen AH, Ferguson SH, Watt CA, Matthews CJD, Kiszka JJ, Rosing-Asvid A, McKinney MA. Varying Diet Composition Causes Striking Differences in Legacy and Emerging Contaminant Concentrations in Killer Whales across the North Atlantic. Environ Sci Technol 2023; 57:16109-16120. [PMID: 37818957 DOI: 10.1021/acs.est.3c05516] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Lipophilic persistent organic pollutants (POPs) tend to biomagnify in food chains, resulting in higher concentrations in species such as killer whales (Orcinus orca) feeding on marine mammals compared to those consuming fish. Advancements in dietary studies include the use of quantitative fatty acid signature analysis (QFASA) and differentiation of feeding habits within and between populations of North Atlantic (NA) killer whales. This comprehensive study assessed the concentrations of legacy and emerging POPs in 162 killer whales from across the NA. We report significantly higher mean levels of polychlorinated biphenyls (PCBs), organochlorine pesticides, and flame retardants in Western NA killer whales compared to those of Eastern NA conspecifics. Mean ∑PCBs ranged from ∼100 mg/kg lipid weight (lw) in the Western NA (Canadian Arctic, Eastern Canada) to ∼50 mg/kg lw in the mid-NA (Greenland, Iceland) to ∼10 mg/kg lw in the Eastern NA (Norway, Faroe Islands). The observed variations in contaminant levels were strongly correlated with diet composition across locations (inferred from QFASA), emphasizing that diet and not environmental variation in contaminant concentrations among locations is crucial in assessing contaminant-associated health risks in killer whales. These findings highlight the urgency for implementing enhanced measures to safely dispose of POP-contaminated waste, prevent further environmental contamination, and mitigate the release of newer and potentially harmful contaminants.
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Affiliation(s)
- Anaïs Remili
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Rune Dietz
- Department of Ecoscience, Arctic Research Centre, Aarhus University, 900 Vestmannaeyjar, Denmark
| | - Christian Sonne
- Department of Ecoscience, Arctic Research Centre, Aarhus University, 900 Vestmannaeyjar, Denmark
| | - Filipa I P Samarra
- University of Iceland, 900 Vestmannaeyjar, Reykjavík 600169-2039, Iceland
| | - Robert J Letcher
- Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Environment and Climate Change Canada, Carleton University, Ottawa, Ontario K1A 0H3, Canada
| | - Audun H Rikardsen
- Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037 Tromsø, Norway
- Norwegian Institute for Nature Research (NINA), N-9296 Tromso, Norway
| | - Steven H Ferguson
- Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, Manitoba R3T 2N6, Canada
| | - Cortney A Watt
- Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, Manitoba R3T 2N6, Canada
| | - Cory J D Matthews
- Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, Manitoba R3T 2N6, Canada
| | - Jeremy J Kiszka
- Institute of Environment, Department of Biological Sciences, Florida International University, North Miami, Florida 33181, United States
| | | | - Melissa A McKinney
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
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Rohner S, Gramer M, Wiesweg I, Scherf-Clavel O, Wohlsein P, Schmelz M, Siebert U, Richter F, Gernert M. Present in the Aquatic Environment, Unclear Evidence in Top Predators-The Unknown Effects of Anti-Seizure Medication on Eurasian Otters ( Lutra lutra) from Northern Germany. Toxics 2023; 11:338. [PMID: 37112566 PMCID: PMC10142713 DOI: 10.3390/toxics11040338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/26/2023] [Accepted: 03/29/2023] [Indexed: 06/19/2023]
Abstract
Emerging contaminants are produced globally at high rates and often ultimately find their way into the aquatic environment. These include substances contained in anti-seizure medication (ASM), which are currently appearing in surface waters at increasing concentrations in Germany. Unintentional and sublethal, chronic exposure to pharmaceuticals such as ASMs has unknown consequences for aquatic wildlife. Adverse effects of ASMs on the brain development are documented in mammals. Top predators such as Eurasian otters (Lutra lutra) are susceptible to the bioaccumulation of environmental pollutants. Still little is known about the health status of the otter population in Germany, while the detection of various pollutants in otter tissue samples has highlighted their role as an indicator species. To investigate potential contamination with pharmaceuticals, Eurasian otter brain samples were screened for selected ASMs via high-performance liquid chromatography and mass spectrometry. Via histology, brain sections were analyzed for the presence of potential associated neuropathological changes. In addition to 20 wild otters that were found dead, a control group of 5 deceased otters in human care was studied. Even though none of the targeted ASMs were detected in the otters, unidentified substances in many otter brains were measured. No obvious pathology was observed histologically, although the sample quality limited the investigations.
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Affiliation(s)
- Simon Rohner
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover Foundation, 30559 Hannover, Germany
| | - Martina Gramer
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover Foundation, 30559 Hannover, Germany
| | - Ivo Wiesweg
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover Foundation, 30559 Hannover, Germany
| | | | - Peter Wohlsein
- Department of Pathology, University of Veterinary Medicine Hannover Foundation, 30559 Hannover, Germany
| | - Martin Schmelz
- Aktion Fischotterschutz e.V, Otter-Zentrum Hankensbüttel, 29386 Hankensbüttel, Germany
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover Foundation, 30559 Hannover, Germany
| | - Franziska Richter
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover Foundation, 30559 Hannover, Germany
| | - Manuela Gernert
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover Foundation, 30559 Hannover, Germany
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Ventura F, Stanworth A, Crofts S, Kuepfer A, Catry P. Local-scale impacts of extreme events drive demographic asynchrony in neighbouring top predator populations. Biol Lett 2023; 19:20220408. [PMID: 36722144 PMCID: PMC9890319 DOI: 10.1098/rsbl.2022.0408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 01/13/2023] [Indexed: 02/02/2023] Open
Abstract
Extreme weather events are among the most critical aspects of climate change, but our understanding of their impacts on biological populations remains limited. Here, we exploit the rare opportunity provided by the availability of concurrent longitudinal demographic data on two neighbouring marine top predator populations (the black-browed albatross, Thalassarche melanophris, breeding in two nearby colonies) hit by an exceptionally violent storm during one study year. The aim of this study is to quantify the demographic impacts of extreme events on albatrosses and test the hypothesis that extreme events would synchronously decrease survival rates of neighbouring populations. Using demographic modelling we found that, contrary to our expectation, the storm affected the survival of albatrosses from only one of the two colonies, more than doubling the annual mortality rate compared to the study average. Furthermore, the effects of storms on adult survival would lead to substantial population declines (up to 2% per year) under simulated scenarios of increased storm frequencies. We, therefore, conclude that extreme events can result in very different local-scale impacts on sympatric populations. Crucially, by driving demographic asynchrony, extreme events can hamper our understanding of the demographic responses of wild populations to mean, long-term shifts in climate.
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Affiliation(s)
- Francesco Ventura
- CESAM, Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Lisboa 1749-016, Portugal
| | | | - Sarah Crofts
- Falklands Conservation, Stanley, FIQQ 1ZZ Falkland Islands, UK
| | - Amanda Kuepfer
- SAERI—South Atlantic Environmental Research Institute, Stanley, FIQQ 1ZZ Falkland Islands, UK
- Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Paulo Catry
- MARE – Marine and Environmental Sciences Centre / ARNET - Aquatic Research Network, ISPA – Instituto Universitário, Rua Jardim do Tabaco 34, Lisboa 1149-041, Portugal
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Jouanneau W, Léandri-Breton DJ, Corbeau A, Herzke D, Moe B, Nikiforov VA, Gabrielsen GW, Chastel O. A Bad Start in Life? Maternal Transfer of Legacy and Emerging Poly- and Perfluoroalkyl Substances to Eggs in an Arctic Seabird. Environ Sci Technol 2022; 56:6091-6102. [PMID: 34874166 DOI: 10.1021/acs.est.1c03773] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In birds, maternal transfer is a major exposure route for several contaminants, including poly- and perfluoroalkyl substances (PFAS). Little is known, however, about the extent of the transfer of the different PFAS compounds to the eggs, especially for alternative fluorinated compounds. In the present study, we measured legacy and emerging PFAS, including Gen-X, ADONA, and F-53B, in the plasma of prelaying black-legged kittiwake females breeding in Svalbard and the yolk of their eggs. We aimed to (1) describe the contaminant levels and patterns in both females and eggs, and (2) investigate the maternal transfer, that is, biological variables and the relationship between the females and their eggs for each compound. Contamination of both females and eggs were dominated by linPFOS then PFUnA or PFTriA. We notably found 7:3 fluorotelomer carboxylic acid─a precursor of long-chain carboxylates─in 84% of the egg yolks, and provide the first documented finding of ADONA in wildlife. Emerging compounds were all below the detection limit in female plasma. There was a linear association between females and eggs for most of the PFAS. Analyses of maternal transfer ratios in females and eggs suggest that the transfer is increasing with PFAS carbon chain length, therefore the longest chain perfluoroalkyl carboxylic acids (PFCAs) were preferentially transferred to the eggs. The mean ∑PFAS in the second-laid eggs was 73% of that in the first-laid eggs. Additional effort on assessing the outcome of maternal transfers on avian development physiology is essential, especially for PFCAs and emerging fluorinated compounds which are under-represented in experimental studies.
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Affiliation(s)
- William Jouanneau
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS - La Rochelle Université, 17031 La Rochelle, France
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway
| | - Don-Jean Léandri-Breton
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS - La Rochelle Université, 17031 La Rochelle, France
- Department of Natural Resource Sciences, McGill University, Ste Anne-de-Bellevue, Quebec H9X 3 V9, Canada
| | - Alexandre Corbeau
- ECOBIO (Ecosystèmes, biodiversité, évolution), UMR 6553 CNRS - Université de Rennes, 35000 Rennes, France
| | - Dorte Herzke
- NILU - Norwegian Institute for Air Research, Fram Centre, NO-9296 Tromsø, Norway
| | - Børge Moe
- NINA - Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
| | - Vladimir A Nikiforov
- NILU - Norwegian Institute for Air Research, Fram Centre, NO-9296 Tromsø, Norway
| | | | - Olivier Chastel
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS - La Rochelle Université, 17031 La Rochelle, France
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Ceulemans R, Guill C, Gaedke U. Top predators govern multitrophic diversity effects in tritrophic food webs. Ecology 2021; 102:e03379. [PMID: 33937982 DOI: 10.1002/ecy.3379] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/22/2020] [Accepted: 02/05/2021] [Indexed: 01/11/2023]
Abstract
It is well known that functional diversity strongly affects ecosystem functioning. However, even in rather simple model communities consisting of only two or, at best, three trophic levels, the relationship between multitrophic functional diversity and ecosystem functioning appears difficult to generalize, because of its high contextuality. In this study, we considered several differently structured tritrophic food webs, in which the amount of functional diversity was varied independently on each trophic level. To achieve generalizable results, largely independent of parametrization, we examined the outcomes of 128,000 parameter combinations sampled from ecologically plausible intervals, with each tested for 200 randomly sampled initial conditions. Analysis of our data was done by training a random forest model. This method enables the identification of complex patterns in the data through partial dependence graphs, and the comparison of the relative influence of model parameters, including the degree of diversity, on food-web properties. We found that bottom-up and top-down effects cascade simultaneously throughout the food web, intimately linking the effects of functional diversity of any trophic level to the amount of diversity of other trophic levels, which may explain the difficulty in unifying results from previous studies. Strikingly, only with high diversity throughout the whole food web, different interactions synergize to ensure efficient exploitation of the available nutrients and efficient biomass transfer to higher trophic levels, ultimately leading to a high biomass and production on the top level. The temporal variation of biomass showed a more complex pattern with increasing multitrophic diversity: while the system initially became less variable, eventually the temporal variation rose again because of the increasingly complex dynamical patterns. Importantly, top predator diversity and food-web parameters affecting the top trophic level were of highest importance to determine the biomass and temporal variability of any trophic level. Overall, our study reveals that the mechanisms by which diversity influences ecosystem functioning are affected by every part of the food web, hampering the extrapolation of insights from simple monotrophic or bitrophic systems to complex natural food webs.
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Affiliation(s)
- Ruben Ceulemans
- Institute of Biochemistry and Biology, University of Potsdam, Am Neuen Palais 10, Potsdam, 14469, Germany
| | - Christian Guill
- Institute of Biochemistry and Biology, University of Potsdam, Am Neuen Palais 10, Potsdam, 14469, Germany
| | - Ursula Gaedke
- Institute of Biochemistry and Biology, University of Potsdam, Am Neuen Palais 10, Potsdam, 14469, Germany
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Andrzejaczek S, Gleiss AC, Lear KO, Pattiaratchi C, Chapple TK, Meekan MG. Depth-dependent dive kinematics suggest cost-efficient foraging strategies by tiger sharks. R Soc Open Sci 2020; 7:200789. [PMID: 32968529 PMCID: PMC7481696 DOI: 10.1098/rsos.200789] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
Tiger sharks, Galeocerdo cuvier, are a keystone, top-order predator that are assumed to engage in cost-efficient movement and foraging patterns. To investigate the extent to which oscillatory diving by tiger sharks conform to these patterns, we used a biologging approach to model their cost of transport. High-resolution biologging tags with tri-axial sensors were deployed on 21 tiger sharks at Ningaloo Reef for durations of 5-48 h. Using overall dynamic body acceleration as a proxy for energy expenditure, we modelled the cost of transport of oscillatory movements of varying geometries in both horizontal and vertical planes for tiger sharks. The cost of horizontal transport was minimized by descending at the smallest possible angle and ascending at an angle of 5-14°, meaning that vertical oscillations conserved energy compared to swimming at a level depth. The reduction of vertical travel costs occurred at steeper angles. The absolute dive angles of tiger sharks increased between inshore and offshore zones, presumably to reduce the cost of transport while continuously hunting for prey in both benthic and surface habitats. Oscillatory movements of tiger sharks conform to strategies of cost-efficient foraging, and shallow inshore habitats appear to be an important habitat for both hunting prey and conserving energy while travelling.
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Affiliation(s)
- Samantha Andrzejaczek
- Oceans Graduate School and The UWA Oceans Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
- The Australian Institute of Marine Science, Crawley, Western Australia 6009, Australia
| | - Adrian C. Gleiss
- Centre for Sustainable Aquatic Ecosystems, Harry Butler Institute, Murdoch University, Murdoch, Western Australia 6150, Australia
| | - Karissa O. Lear
- Centre for Sustainable Aquatic Ecosystems, Harry Butler Institute, Murdoch University, Murdoch, Western Australia 6150, Australia
| | - Charitha Pattiaratchi
- Oceans Graduate School and The UWA Oceans Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Taylor K. Chapple
- Coastal Oregon Marine Experiment Station, Oregon State University, Newport, OR 97365, USA
- Hopkins Marine Station, Stanford University, Pacific Grove, CA, 93950, USA
| | - Mark G. Meekan
- The Australian Institute of Marine Science, Crawley, Western Australia 6009, Australia
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Brown-Vuillemin S, Barreau T, Caraguel JM, Iglésias SP. Trophic ecology and ontogenetic diet shift of the blue skate (Dipturus cf. flossada). J Fish Biol 2020; 97:515-526. [PMID: 32447756 DOI: 10.1111/jfb.14407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 05/12/2020] [Accepted: 05/21/2020] [Indexed: 06/11/2023]
Abstract
Knowledge of skate ecology must be improved to ensure their effective protection. This study represents the first description of diet composition for one of the largest European rajid, the blue skate Dipturus cf. flossada. A total of 346 specimens collected in the Celtic Sea from 2012 to 2015 were analysed for their gut content, with respect to individual total length, maturity stage and sex. Overall, the blue skate diet mainly consisted of shrimps and prawns, crabs and teleost fishes. Nonmetric multidimensional scaling and ANOSIM analyses revealed major ontogenetic shifts in the feeding strategy that were related to size and maturity, but not to sex. Shrimps and prawns, mostly composed of Crangon allmanni, dominated the diet of small and immature individuals, while mod-size skate primarily preyed on crabs. The prevalence of crustaceans decreased with size and maturity, and was gradually replaced by teleost fishes in large mature individuals. A concomitant increase of the trophic level with size revealed that large blue skate become a top predator within the ecosystem. These results highlight the need to include ontogenetic changes in the diet description. As individuals grow and mature, blue skates can play a fundamental role in the structure of the Celtic Sea food web.
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Affiliation(s)
- Sarah Brown-Vuillemin
- Muséum National d'Histoire Naturelle, Station Marine de Concarneau, Concarneau, France
| | - Thomas Barreau
- Muséum National d'Histoire Naturelle, Station Marine de Concarneau, Concarneau, France
| | - Jean-Marie Caraguel
- Muséum National d'Histoire Naturelle, Station Marine de Concarneau, Concarneau, France
| | - Samuel P Iglésias
- Institut de Systématique, Évolution, Biodiversité, Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, Station Marine de Concarneau, Concarneau, France
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May C, Meyer L, Whitmarsh S, Huveneers C. Eyes on the size: accuracy of visual length estimates of white sharks, Carcharodon carcharias. R Soc Open Sci 2019; 6:190456. [PMID: 31218071 PMCID: PMC6549950 DOI: 10.1098/rsos.190456] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 04/26/2019] [Indexed: 05/21/2023]
Abstract
Visual estimates have been used extensively to determine the length of large organisms that are logistically challenging to measure. However, there has been little effort to quantify the accuracy or validity of this technique despite inaccurate size estimates leading to incorrect population assessments and misinformed management strategies. Here, we compared visually estimated total length measurements of white sharks, Carcharodon carcharias, during cage-diving operations with measurements obtained from stereo-video cameras and assessed the accuracy of those estimates in relation to suspected biases (shark size, and observer experience and gender) using generalized linear mixed-models and linear regressions. Observer experience on board cage-diving vessels had the greatest effect on the accuracy of visual length estimates, with scientists being more accurate (mean accuracy ± standard error: 23.0 ± 16.5 cm) than crew (39.9 ± 33.8 cm) and passengers (49.4 ± 38.5 cm). Observer gender and shark size had no impact on the overall accuracy of visual length estimates, but passengers overestimated sharks less than 3 m and underestimated sharks greater than 3 m. Our findings show that experience measuring animals is the most substantial driver of accurate visual length estimates regardless of the amount of exposure to the species being measured. Scientists were most accurate, even though crew observe white sharks more frequently. Our results show that visual length estimates are not impacted by shark size and are a valid measurement tool for many aspects of C. carcharias research, provided they come from people who have previously been involved in measuring animals, i.e. scientists.
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11
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Paxton AB, Blair E, Blawas C, Fatzinger MH, Marens M, Holmberg J, Kingen C, Houppermans T, Keusenkothen M, McCord J, Silliman BR, Penfold LM. Citizen science reveals female sand tiger sharks (Carcharias taurus) exhibit signs of site fidelity on shipwrecks. Ecology 2019; 100:e02687. [PMID: 31009086 DOI: 10.1002/ecy.2687] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/07/2019] [Accepted: 02/20/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Avery B Paxton
- South-East Zoo Alliance for Reproduction & Conservation, 581705 White Oak Road, Yulee, Florida, 32097, USA.,Nicholas School of the Environment, Duke University Marine Lab, 135 Duke Marine Lab Road, Beaufort, North Carolina, 28516, USA
| | - Erica Blair
- Nicholas School of the Environment, Duke University Marine Lab, 135 Duke Marine Lab Road, Beaufort, North Carolina, 28516, USA.,Department of Biology, Duke University, 130 Science Drive, Durham, North Carolina, 27708, USA
| | - Camryn Blawas
- Department of Biology, University of North Carolina at Chapel Hill, 120 South Road, Chapel Hill, North Carolina, 27599, USA
| | - Michael H Fatzinger
- North Carolina Aquarium at Pine Knoll Shores, 1 Roosevelt Boulevard, Pine Knoll Shores, North Carolina, 28512, USA
| | - Madeline Marens
- North Carolina Aquarium at Fort Fisher, 900 Loggerhead Road, Kure Beach, North Carolina, 28449, USA.,Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Road, Wilmington, North Carolina, 28403, USA
| | - Jason Holmberg
- Wild Me, 1726 North Terry Street, Portland, Oregon, 92717, USA
| | - Colin Kingen
- Wild Me, 1726 North Terry Street, Portland, Oregon, 92717, USA
| | - Tanya Houppermans
- Blue Elements Imaging LLC, 711 Edwards Drive, Fredericksburg, Virginia, 22405, USA
| | - Mark Keusenkothen
- Diving and Water Safety Office, East Carolina University, Building 43, Greenville, North Carolina, 27858, USA
| | - John McCord
- Coastal Studies Institute, East Carolina University, 850 NC-345, Wanchese, North Carolina, 27981, USA
| | - Brian R Silliman
- Nicholas School of the Environment, Duke University Marine Lab, 135 Duke Marine Lab Road, Beaufort, North Carolina, 28516, USA
| | - Linda M Penfold
- South-East Zoo Alliance for Reproduction & Conservation, 581705 White Oak Road, Yulee, Florida, 32097, USA
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12
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Vasconcelos FR, Diehl S, Rodríguez P, Hedström P, Karlsson J, Byström P. Bottom-up and top-down effects of browning and warming on shallow lake food webs. Glob Chang Biol 2019; 25:504-521. [PMID: 30430702 DOI: 10.1111/gcb.14521] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 10/11/2018] [Accepted: 10/16/2018] [Indexed: 05/22/2023]
Abstract
Productivity and trophic structure of aquatic ecosystems result from a complex interplay of bottom-up and top-down forces that operate across benthic and pelagic food web compartments. Projected global changes urge the question how this interplay will be affected by browning (increasing input of terrestrial dissolved organic matter), nutrient enrichment and warming. We explored this with a process-based model of a shallow lake food web consisting of benthic and pelagic components (abiotic resources, primary producers, grazers, carnivores), and compared model expectations with the results of a browning and warming experiment in nutrient-poor ponds harboring a boreal lake community. Under low nutrient conditions, the model makes three major predictions. (a) Browning reduces light and increases nutrient supply; this decreases benthic and increases pelagic production, gradually shifting productivity from the benthic to the pelagic habitat. (b) Because of active habitat choice, fish exert top-down control on grazers and benefit primary producers primarily in the more productive of the two habitats. (c) Warming relaxes top-down control of grazers by fish and decreases primary producer biomass, but effects of warming are generally small compared to effects of browning and nutrient supply. Experimental results were consistent with most model predictions for browning: light penetration, benthic algal production, and zoobenthos biomass decreased, and pelagic nutrients and pelagic algal production increased with browning. Also consistent with expectations, warming had negative effects on benthic and pelagic algal biomass and weak effects on algal production and zoobenthos and zooplankton biomass. Inconsistent with expectations, browning had no effect on zooplankton and warming effects on fish depended on browning. The model is applicable also to nutrient-rich systems, and we propose that it is a useful tool for the exploration of the consequences of different climate change scenarios for productivity and food web dynamics in shallow lakes, the worldwide most common lake type.
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Affiliation(s)
- Francisco Rivera Vasconcelos
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
- Integrated Science Lab - IceLab, Umeå University, Umeå, Sweden
| | - Sebastian Diehl
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
- Integrated Science Lab - IceLab, Umeå University, Umeå, Sweden
| | - Patricia Rodríguez
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
- Austral Centre for Scientific Research (CADIC-CONICET), Ushuaia, Tierra del Fuego, Argentina
| | - Per Hedström
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
| | - Jan Karlsson
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
| | - Pär Byström
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
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13
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Peterson SH, Ackerman JT, Crocker DE, Costa DP. Foraging and fasting can influence contaminant concentrations in animals: an example with mercury contamination in a free-ranging marine mammal. Proc Biol Sci 2019; 285:rspb.2017.2782. [PMID: 29436501 DOI: 10.1098/rspb.2017.2782] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 01/08/2018] [Indexed: 11/12/2022] Open
Abstract
Large fluctuations in animal body mass in relation to life-history events can influence contaminant concentrations and toxicological risk. We quantified mercury concentrations in adult northern elephant seals (Mirounga angustirostris) before and after lengthy at sea foraging trips (n = 89) or fasting periods on land (n = 27), and showed that mercury concentrations in blood and muscle changed in response to these events. The highest blood mercury concentrations were observed after the breeding fast, whereas the highest muscle mercury concentrations were observed when seals returned to land to moult. Mean female blood mercury concentrations decreased by 30% across each of the two annual foraging trips, demonstrating a foraging-associated dilution of mercury concentrations as seals gained mass. Blood mercury concentrations increased by 103% and 24% across the breeding and moulting fasts, respectively, demonstrating a fasting-associated concentration of mercury as seals lost mass. In contrast to blood, mercury concentrations in female's muscle increased by 19% during the post-breeding foraging trip and did not change during the post-moulting foraging trip. While fasting, female muscle mercury concentrations increased 26% during breeding, but decreased 14% during moulting. Consequently, regardless of exposure, an animal's contaminant concentration can be markedly influenced by their annual life-history events.
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Affiliation(s)
- Sarah H Peterson
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA .,Institute of Marine Science, University of California, Santa Cruz, Santa Cruz, CA, USA.,US Geological Survey, Western Ecological Research Center, Dixon Field Station, Dixon, CA, USA
| | - Joshua T Ackerman
- US Geological Survey, Western Ecological Research Center, Dixon Field Station, Dixon, CA, USA
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
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14
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Doody JS, Rhind D, Green B, Castellano C, McHenry C, Clulow S. Chronic effects of an invasive species on an animal community. Ecology 2017; 98:2093-2101. [PMID: 28477376 DOI: 10.1002/ecy.1889] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/19/2017] [Accepted: 04/05/2017] [Indexed: 11/08/2022]
Abstract
Invasive species can trigger trophic cascades in animal communities, but published cases involving their removal of top predators are extremely rare. An exception is the invasive cane toad (Rhinella marina) in Australia, which has caused severe population declines in monitor lizards, triggering trophic cascades that facilitated dramatic and sometimes unexpected increases in several prey of the predators, including smaller lizards, snakes, turtles, crocodiles, and birds. Persistence of isolated populations of these predators with a decades-long sympatry with toads suggests the possibility of recovery, but alternative explanations are possible. Confirming predator recovery requires longer-term study of populations with both baseline and immediate post-invasion densities. Previously, we quantified short-term impacts of invasive cane toads on animal communities over seven years at two sites in tropical Australia. Herein, we test the hypothesis that predators have begun to recover by repeating the study 12 yr after the initial toad invasion. The three predatory lizards that experienced 71-97% declines in the short-term study showed no sign of recovery, and indeed a worse fate: two of the three species were no longer detectable in 630 km of river surveys, suggesting local extirpation. Two mesopredators that had increased markedly in the short term due to these predator losses showed diverse responses in the medium term; a small lizard species increased by ~500%, while populations of a snake species showed little change. Our results indicate a system still in ecological turmoil, having not yet reached a "new equilibrium" more than a decade after the initial invasion; predator losses due to this toxic invasive species, and thus downstream effects, were not transient. Given that cane toads have proven too prolific to eradicate or control, we suggest that recovery of impacted predators must occur unassisted by evolutionary means: dispersal into extinction sites from surviving populations with alleles for toxin resistance or toad avoidance. Evolution and subsequent dispersal may be the only solution for a number of species or communities affected by invasive species for which control is either prohibitively expensive, or not possible.
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Affiliation(s)
- J Sean Doody
- Department of Biological Sciences, Southeastern Louisiana University, Hammond, Louisiana, 70402, USA.,School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, 2308, Australia
| | - David Rhind
- School of Biological Sciences, Monash University, Clayton, Victoria, 3800, Australia
| | - Brian Green
- Institute for Applied Ecology, University of Canberra, Canberra, Australian Capital Territory, 2601, Australia
| | - Christina Castellano
- Institute for Applied Ecology, University of Canberra, Canberra, Australian Capital Territory, 2601, Australia
| | - Colin McHenry
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, 2308, Australia
| | - Simon Clulow
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, 2308, Australia
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15
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Ishikawa NF, Hayashi F, Sasaki Y, Chikaraishi Y, Ohkouchi N. Trophic discrimination factor of nitrogen isotopes within amino acids in the dobsonfly Protohermes grandis (Megaloptera: Corydalidae) larvae in a controlled feeding experiment. Ecol Evol 2017; 7:1674-1679. [PMID: 28331578 PMCID: PMC5355178 DOI: 10.1002/ece3.2728] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 12/07/2016] [Accepted: 12/18/2016] [Indexed: 11/12/2022] Open
Abstract
The trophic discrimination factor (TDF) of nitrogen isotopes (15N/14N) within amino acids, between a stream-dwelling dobsonfly larva (Protohermes grandis: Megaloptera; Corydalidae) and its diet (chironomid larvae), was determined in controlled feeding experiments. Last-instar larvae of P. grandis were collected from the Yozawa-gawa River, central Japan, and reared in the laboratory. After fed to satiation for 1 month, one group of larvae was each fed one living chironomid larva per day for 4 weeks, while a second group was starved for 8 weeks. The larvae were harvested at intervals and the nitrogen isotopic composition of glutamic acid (δ15NGlu) and phenylalanine (δ15NPhe) were determined to calculate TDF. The mean TDF of satiated and starved larvae were 7.1‰ ± 0.5‰ (n = 3) and 7.3‰ ± 0.5‰ (n = 5), respectively. Thus, the TDF for P. grandis larvae in this study was similar to that reported for other arthropods (approximately 7‰) and was independent of satiation or starvation. A previous study of wild P. grandis larvae, based on the δ15NGlu and δ15NPhe values, estimated its trophic position (TP) as approximately 2.0 ± 0.1 (n = 5), a low value close to that of algivores, although they are generally characterized as carnivores (usually accepted as TP ≥ 3). The TDF for P. grandis larvae suggests that their low TPs in nature were caused by incorporation of vascular plant-derived amino acids (with a different δ15N profile from that of algae) and not by an unusually low TDF or by the effects of the satiation/starvation on amino acid metabolism.
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Affiliation(s)
- Naoto F Ishikawa
- Japan Agency for Marine-Earth Science and Technology Yokosuka Kanagawa Japan; Present address: ETH Zürich Sonneggstrasse 58092 Zürich Switzerland
| | - Fumio Hayashi
- Department of Biology Tokyo Metropolitan University Hachioji Tokyo Japan
| | - Yoko Sasaki
- Japan Agency for Marine-Earth Science and Technology Yokosuka Kanagawa Japan
| | - Yoshito Chikaraishi
- Japan Agency for Marine-Earth Science and Technology Yokosuka Kanagawa Japan; Present address: Institute of Low Temperature Science Hokkaido University Kita 19, Nishi 8, Kita-ku Sapporo 060-0819 Japan
| | - Naohiko Ohkouchi
- Japan Agency for Marine-Earth Science and Technology Yokosuka Kanagawa Japan
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16
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van Bommel L, Johnson CN. Livestock guardian dogs as surrogate top predators? How Maremma sheepdogs affect a wildlife community. Ecol Evol 2016; 6:6702-6711. [PMID: 27777741 PMCID: PMC5058539 DOI: 10.1002/ece3.2412] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 07/29/2016] [Accepted: 08/04/2016] [Indexed: 11/08/2022] Open
Abstract
Use of livestock guardian dogs (LGDs) to reduce predation on livestock is increasing. However, how these dogs influence the activity of wildlife, including predators, is not well understood. We used pellet counts and remote cameras to investigate the effects of free ranging LGDs on four large herbivores (eastern gray kangaroo, common wombat, swamp wallaby, and sambar deer) and one mesopredator (red fox) in Victoria, Australia. Generalized mixed models and one- and two-species detection models were used to assess the influence of the presence of LGDs on detection of the other species. We found avoidance of LGDs in four species. Swamp wallabies and sambar deer were excluded from areas occupied by LGDs; gray kangaroos showed strong spatial and temporal avoidance of LGD areas; foxes showed moderately strong spatial and temporal avoidance of LGD areas. The effect of LGDs on wombats was unclear. Avoidance of areas with LGDs by large herbivores can benefit livestock production by reducing competition for pasture and disease transmission from wildlife to livestock, and providing managers with better control over grazing pressure. Suppression of mesopredators could benefit the small prey of those species. Synthesis and applications: In pastoral areas, LGDs can function as a surrogate top-order predator, controlling the local distribution and affecting behavior of large herbivores and mesopredators. LGDs may provide similar ecological functions to those that in many areas have been lost with the extirpation of native large carnivores.
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Affiliation(s)
- Linda van Bommel
- School of Biological Sciences University of Tasmania Hobart Tas. Australia; Fenner School of Environment and Society Australian National University Canberra ACT Australia
| | - Chris N Johnson
- School of Biological Sciences University of Tasmania Hobart Tas. Australia
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17
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Mueller AK, Chakarov N, Heseker H, Krüger O. Intraguild predation leads to cascading effects on habitat choice, behaviour and reproductive performance. J Anim Ecol 2016; 85:774-84. [PMID: 26781959 DOI: 10.1111/1365-2656.12493] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 11/29/2015] [Indexed: 11/30/2022]
Abstract
Intraguild predation (IGP) is a commonly recognized mechanism influencing the community structure of predators, but the complex interactions are notoriously difficult to disentangle. The mesopredator suppression hypothesis predicts that a superpredator may either simultaneously repress two mesopredators, restrain the dominant one and thereby release the subdominant mesopredator, or elicit different responses by both mesopredators. We show the outcome arising from such conditions in a three-level predator assemblage (Eurasian eagle owl Bubo bubo L., northern goshawk Accipiter gentilis L. and common buzzard Buteo buteo L.) studied over 25 years. In the second half of the study period, the eagle owl re-colonized the study area, thereby providing a natural experiment of superpredator introduction. We combined this set-up with detailed GIS analysis of habitat use and a field experiment simulating intrusion by the superpredator into territories of the subdominant mesopredator, the buzzard. Although population trends were positive for all three species in the assemblage, the proportion of failed breeding attempts increased significantly in both mesopredators after the superpredator re-colonized the area. We predicted that superpredator-induced niche shifts in the dominant mesopredator may facilitate mesopredator coexistence in superpredator-free refugia. We found significant changes in nesting habitat choice in goshawk, but not in buzzard. Since competition for enemy-free refugia and the rapid increase in population density may have constrained niche shifts of the subdominant mesopredator, we further predicted behavioural changes in response to the superpredator. The field experiment indeed showed a significant increase in aggressive response of buzzards towards eagle owl territory intrusion over the course of 10 years, probably due to phenotypic plasticity in the response towards superpredation risk. Overall, our results show that intraguild predation can be a powerful force of behavioural change, simultaneously influencing habitat use and aggressiveness in predator communities. These changes might help to buffer mesopredator populations against the negative effects of intraguild predation.
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Affiliation(s)
- Anna-Katharina Mueller
- Department of Animal Behaviour, Bielefeld University, PO Box 100131, Bielefeld, 33501, Germany
| | - Nayden Chakarov
- Department of Animal Behaviour, Bielefeld University, PO Box 100131, Bielefeld, 33501, Germany.,Department of Biology, Molecular Ecology and Evolution Lab, Lund University, Ecology Building, Lund, SE-22362, Sweden
| | - Hanna Heseker
- Department of Animal Behaviour, Bielefeld University, PO Box 100131, Bielefeld, 33501, Germany
| | - Oliver Krüger
- Department of Animal Behaviour, Bielefeld University, PO Box 100131, Bielefeld, 33501, Germany
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18
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Herrera-Rangel J, Jiménez-Carmona E, Armbrecht I. Monitoring the Diversity of Hunting Ants (Hymenoptera: Formicidae) on a Fragmented and Restored Andean Landscape. Environ Entomol 2015; 44:1287-1298. [PMID: 26314006 DOI: 10.1093/ee/nvv103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 06/16/2015] [Indexed: 06/04/2023]
Abstract
Hunting ants are predators of organisms belonging to different trophic levels. Their presence, abundance, and diversity may reflect the diversity of other ants and contribute to evaluate habitat conditions. Between 2003 and 2005 the restoration of seven corridors in an Andean rural landscape of Colombia was performed. The restoration took place in lands that were formerly either forestry plantations or pasturelands. To evaluate restoration progress, hunting ants were intensely sampled for 7 yr, using sifted leaf litter and mini-Winkler, and pitfall traps in 21 plots classified into five vegetation types: forests, riparian forests, two types of restored corridors, and pasturelands. The ant communities were faithful to their habitat over time, and the main differences in ant composition, abundance, and richness were due to differences among land use types. The forests and riparian forests support 45% of the species in the landscape while the restored corridors contain between 8.3-25%. The change from forest to pasturelands represents a loss of 80% of the species. Ant composition in restored corridors was significantly different than in forests but restored corridors of soil of forestry plantations retained 16.7% more species than restored corridors from pasturelands. Ubiquitous hunting ants, Hypoponera opacior (Forel) and Gnamptogenys ca andina were usually associated with pastures and dominate restored corridors. Other cryptic, small, and specialized hunting ants are not present in the restored corridors. Results suggest that the history of land use is important for the biodiversity of hunting ants but also that corridors have not yet effectively contributed toward conservation goals.
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Affiliation(s)
- J Herrera-Rangel
- Biology Department, Universidad del Valle, Calle 13 # 100-00 Ed. 320. AA 25360, Cali, Colombia.
| | - E Jiménez-Carmona
- Biology Department, Universidad del Valle, Calle 13 # 100-00 Ed. 320. AA 25360, Cali, Colombia
| | - I Armbrecht
- Biology Department, Universidad del Valle, Calle 13 # 100-00 Ed. 320. AA 25360, Cali, Colombia. Agroecology Section, Agricultural Science Department, University of Goettingen, Grisebachstr. 6, 37077, Goettingen, Germany
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19
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Cordes LS, Thompson PM. Variation in breeding phenology provides insights into drivers of long-term population change in harbour seals. Proc Biol Sci 2013; 280:20130847. [PMID: 23782881 PMCID: PMC3712417 DOI: 10.1098/rspb.2013.0847] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 05/28/2013] [Indexed: 11/12/2022] Open
Abstract
Phenological trends provide important indicators of environmental change and population dynamics. However, the use of untested population-level measures can lead to incorrect conclusions about phenological trends, particularly when changes in population structure or density are ignored. We used individual-based estimates of birth date and lactation duration of harbour seals (Phoca vitulina) to investigate energetic consequences of changes in pupping phenology. Using generalized linear mixed models, we first demonstrate annual variation in pupping phenology. Second, we show a negative relationship between lactation duration and the timing of pupping, indicating that females who pup early nurse their pups longer, thereby highlighting lactation duration as a useful proxy of female condition and resource availability. Third, individual-based data were used to derive a population-level proxy that demonstrated an advance in pupping date over the last 25 years, co-incident with a reduction in population abundance that resulted from fisheries-related shootings. These findings demonstrate that phenological studies examining the impacts of climate change on mammal populations must carefully control for changes in population density and highlight how joint investigations of phenological and demographic change provide insights into the drivers of population declines.
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Affiliation(s)
- Line S Cordes
- Institute of Biological and Environmental Sciences, University of Aberdeen, Lighthouse Field Station, George Street, Cromarty IV11 8YJ, UK.
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