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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] [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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Voysey MD, de Bruyn PJN, Davies AB. Are hippos Africa's most influential megaherbivore? A review of ecosystem engineering by the semi-aquatic common hippopotamus. Biol Rev Camb Philos Soc 2023; 98:1509-1529. [PMID: 37095627 DOI: 10.1111/brv.12960] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 03/30/2023] [Accepted: 04/03/2023] [Indexed: 04/26/2023]
Abstract
Megaherbivores perform vital ecosystem engineering roles, and have their last remaining stronghold in Africa. Of Africa's remaining megaherbivores, the common hippopotamus (Hippopotamus amphibius) has received the least scientific and conservation attention, despite how influential their ecosystem engineering activities appear to be. Given the potentially crucial ecosystem engineering influence of hippos, as well as mounting conservation concerns threatening their long-term persistence, a review of the evidence for hippos being ecosystem engineers, and the effects of their engineering, is both timely and necessary. In this review, we assess, (i) aspects of hippo biology that underlie their unique ecosystem engineering potential; (ii) evaluate hippo ecological impacts in terrestrial and aquatic environments; (iii) compare the ecosystem engineering influence of hippos to other extant African megaherbivores; (iv) evaluate factors most critical to hippo conservation and ecosystem engineering; and (v) highlight future research directions and challenges that may yield new insights into the ecological role of hippos, and of megaherbivores more broadly. We find that a variety of key life-history traits determine the hippo's unique influence, including their semi-aquatic lifestyle, large body size, specialised gut anatomy, muzzle structure, small and partially webbed feet, and highly gregarious nature. On land, hippos create grazing lawns that contain distinct plant communities and alter fire spatial extent, which shapes woody plant demographics and might assist in maintaining fire-sensitive riverine vegetation. In water, hippos deposit nutrient-rich dung, stimulating aquatic food chains and altering water chemistry and quality, impacting a host of different organisms. Hippo trampling and wallowing alters geomorphological processes, widening riverbanks, creating new river channels, and forming gullies along well-utilised hippo paths. Taken together, we propose that these myriad impacts combine to make hippos Africa's most influential megaherbivore, specifically because of the high diversity and intensity of their ecological impacts compared with other megaherbivores, and because of their unique capacity to transfer nutrients across ecosystem boundaries, enriching both terrestrial and aquatic ecosystems. Nonetheless, water pollution and extraction for agriculture and industry, erratic rainfall patterns and human-hippo conflict, threaten hippo ecosystem engineering and persistence. Therefore, we encourage greater consideration of the unique role of hippos as ecosystem engineers when considering the functional importance of megafauna in African ecosystems, and increased attention to declining hippo habitat and populations, which if unchecked could change the way in which many African ecosystems function.
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Affiliation(s)
- Michael D Voysey
- Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Avenue, Cambridge, MA, 02138, USA
| | - P J Nico de Bruyn
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Andrew B Davies
- Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Avenue, Cambridge, MA, 02138, USA
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3
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Inundation area drives hippo group aggregation and dispersal in a seasonal floodplain system. Mamm Biol 2022. [DOI: 10.1007/s42991-022-00286-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Thévenet J, Grimault N, Fonseca P, Mathevon N. Voice-mediated interactions in a megaherbivore. Curr Biol 2022; 32:R70-R71. [DOI: 10.1016/j.cub.2021.12.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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5
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Xu D, Lin H, Qiu W, Ge M, Chen Z, Wu C, You Y, Lu X, Wei C, Liu J, Guo X, Shi J. Hydrogen-bonded silicene nanosheets of engineered bandgap and selective degradability for photodynamic therapy. Biomaterials 2021; 278:121172. [DOI: doi.org/10.1016/j.biomaterials.2021.121172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
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6
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Hydrogen-bonded silicene nanosheets of engineered bandgap and selective degradability for photodynamic therapy. Biomaterials 2021; 278:121172. [PMID: 34653935 DOI: 10.1016/j.biomaterials.2021.121172] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 09/27/2021] [Accepted: 09/30/2021] [Indexed: 11/24/2022]
Abstract
Silicon, a highly biocompatible and ubiquitous chemical element in living systems, exhibits great potentials in biomedical applications. However, the silicon-based nanomaterials such as silica and porous silicon have been largely limited to only serving as carriers for delivery systems, due to the lack of intrinsic functionalities of silicon. This work presents the facile construction of a two-dimensional (2D) hydrogen-bonded silicene (H-silicene) nanosystem which is highlighted with tunable bandgap and selective degradability for tumor-specific photodynamic therapy facilely by surface covalent modification of hydrogen atoms. Briefly, the H-silicene nanosheet material is selectively degradable in normal neutral tissues but rather stable in the mildly acidic tumor microenvironment (TME) for achieving efficient photodynamic therapy (PDT). Such a 2D hydrogen-bonded silicene nanosystem featuring the tunable bandgap and tumor-selective degradability provides a new paradigm for the application of multi-functional two-dimensional silicon-based biomaterials towards the diagnosis and treatments of cancer and other diseases.
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Hixon SW, Douglass KG, Crowley BE, Rakotozafy LMA, Clark G, Anderson A, Haberle S, Ranaivoarisoa JF, Buckley M, Fidiarisoa S, Mbola B, Kennett DJ. Late Holocene spread of pastoralism coincides with endemic megafaunal extinction on Madagascar. Proc Biol Sci 2021; 288:20211204. [PMID: 34284627 PMCID: PMC8292765 DOI: 10.1098/rspb.2021.1204] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 06/28/2021] [Indexed: 11/24/2022] Open
Abstract
Recently expanded estimates for when humans arrived on Madagascar (up to approximately 10 000 years ago) highlight questions about the causes of the island's relatively late megafaunal extinctions (approximately 2000-500 years ago). Introduced domesticated animals could have contributed to extinctions, but the arrival times and past diets of exotic animals are poorly known. To conduct the first explicit test of the potential for competition between introduced livestock and extinct endemic megafauna in southern and western Madagascar, we generated new radiocarbon and stable carbon and nitrogen isotope data from the bone collagen of introduced ungulates (zebu cattle, ovicaprids and bushpigs, n = 66) and endemic megafauna (pygmy hippopotamuses, giant tortoises and elephant birds, n = 68), and combined these data with existing data from endemic megafauna (n = 282, including giant lemurs). Radiocarbon dates confirm that introduced and endemic herbivores briefly overlapped chronologically in this region between 1000 and 800 calibrated years before present (cal BP). Moreover, stable isotope data suggest that goats, tortoises and hippos had broadly similar diets or exploited similar habitats. These data support the potential for both direct and indirect forms of competition between introduced and endemic herbivores. We argue that competition with introduced herbivores, mediated by opportunistic hunting by humans and exacerbated by environmental change, contributed to the late extinction of endemic megafauna on Madagascar.
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Affiliation(s)
- Sean W. Hixon
- Department of Anthropology, University of California at Santa Barbara, Santa Barbara, CA, USA
| | - Kristina G. Douglass
- Department of Anthropology, Pennsylvania State University, State College, PA, USA
| | - Brooke E. Crowley
- Department of Geology, University of Cincinnati, Cincinnati, OH, USA
- Department of Anthropology, University of Cincinnati, Cincinnati, OH, USA
| | | | - Geoffrey Clark
- Department of Archaeology and Natural History, College of Asia and the Pacific, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Atholl Anderson
- Department of Archaeology and Natural History, College of Asia and the Pacific, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Simon Haberle
- Department of Archaeology and Natural History, College of Asia and the Pacific, The Australian National University, Canberra, Australian Capital Territory, Australia
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, School of Culture, History and Language (CAP), The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Jean Freddy Ranaivoarisoa
- Department of Biological Anthropology and Sustainable Development, University of Antananarivo, Madagascar
| | - Michael Buckley
- School of Natural Sciences, Manchester Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, UK
| | - Salomon Fidiarisoa
- Département des Sciences Biologiques, Faculté des Sciences, Université de Tuléar, BP 185, Tuléar, 601, Madagascar
| | - Balzac Mbola
- Département des Sciences Biologiques, Faculté des Sciences, Université de Tuléar, BP 185, Tuléar, 601, Madagascar
| | - Douglas J. Kennett
- Department of Anthropology, University of California at Santa Barbara, Santa Barbara, CA, USA
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Wang T, Li Z, Wei J, Zheng D, Wang C, Xu C, Chen W, Wang B. Establishment and characterization of fibroblast cultures derived from a female common hippopotamus (Hippopotamus amphibius) skin biopsy. Cell Biol Int 2021; 45:1571-1578. [PMID: 33760319 DOI: 10.1002/cbin.11596] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 02/15/2021] [Accepted: 03/21/2021] [Indexed: 01/23/2023]
Abstract
The population decline of the common hippopotamus (Hippopotamus amphibius) has necessitated the preservation of their genetic resources for species conservation and research. Of all actions, cryopreservation of fibroblast cell cultures derived from an animal biopsy is considered a simple but efficient means. Nevertheless, preserving viable cell cultures of the common hippopotamus has not been achieved to our knowledge. To this end, we established and characterized fibroblast cell cultures from the skin sample of a newborn common hippopotamus in this study. By combining the tissue explant direct culture and enzymatic digestion methods, we isolated a great number of cells with typical fibroblastic morphology and high viability. Neither bacteria/fungi nor mycoplasma was detectable in the cell cultures throughout the study. The population doubling time was 34 h according to the growth curve. Karyotyping based on Giemsa staining showed that the cultured cells were diploid with 36 chromosomes in all, one pair of which was sex chromosomes. The amplified mitochondrial cytochrome C oxidase subunit I gene sequence of the cultured cells was 99.26% identical with that of the registered H. amphibius complete mitochondrial DNA, confirming the species of origin of the cells. Flow cytometry and immunofluorescence staining results revealed that the detected cells were positive for fibroblast markers, S100A4, and vimentin. In conclusion, we generated the fibroblast cell cultures from a common hippopotamus and identified their characteristics using multiple techniques. We believe the cryopreserved cells could be useful genetic materials for future research.
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Affiliation(s)
- Tao Wang
- Biological Resource Center of Plants, Animals and Microorganisms, China National GeneBank, BGI-Shenzhen, Shenzhen, China.,Shenzhen Key Laboratory of Environmental Microbial Genomics and Application, BGI-Shenzhen, Shenzhen, China
| | - Zelong Li
- Biological Resource Center of Plants, Animals and Microorganisms, China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Jinpu Wei
- Biological Resource Center of Plants, Animals and Microorganisms, China National GeneBank, BGI-Shenzhen, Shenzhen, China.,Shenzhen Key Laboratory of Environmental Microbial Genomics and Application, BGI-Shenzhen, Shenzhen, China
| | - Dongmin Zheng
- Biological Resource Center of Plants, Animals and Microorganisms, China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Chen Wang
- Guangzhou Zoo & Guangzhou Wildlife Research Center, Guangzhou, China
| | - Chang Xu
- Biological Resource Center of Plants, Animals and Microorganisms, China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Wu Chen
- Guangzhou Zoo & Guangzhou Wildlife Research Center, Guangzhou, China
| | - Bo Wang
- Biological Resource Center of Plants, Animals and Microorganisms, China National GeneBank, BGI-Shenzhen, Shenzhen, China.,Shenzhen Key Laboratory of Environmental Microbial Genomics and Application, BGI-Shenzhen, Shenzhen, China
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Pausas JG, Bond WJ. On the Scale of the Terrestrial Recycling Pathways. Trends Ecol Evol 2020; 36:11-12. [PMID: 33190950 DOI: 10.1016/j.tree.2020.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 10/21/2020] [Indexed: 10/23/2022]
Affiliation(s)
- Juli G Pausas
- Centro de Investigaciones sobre Desertificación (CIDE-CSIC), Valencia, Spain.
| | - William J Bond
- Department of Biological Sciences, University of Cape Town, Cape Town, South Africa; South African Environmental Observation Network, National Research Foundation, Claremont, South Africa
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10
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Fritsch CJ, Downs CT. Evaluation of low‐cost consumer‐grade
UAVs
for conducting comprehensive high‐frequency population censuses of hippopotamus populations. CONSERVATION SCIENCE AND PRACTICE 2020. [DOI: 10.1111/csp2.281] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
- Camille J. Fritsch
- Centre for Functional Biodiversity School of Life Sciences, University of KwaZulu‐Natal Scottsville South Africa
| | - Colleen T. Downs
- Centre for Functional Biodiversity School of Life Sciences, University of KwaZulu‐Natal Scottsville South Africa
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Utete B. A review of some aspects of the ecology, population trends, threats and conservation strategies for the common hippopotamus, Hippopotamus amphibius L, in Zimbabwe. AFRICAN ZOOLOGY 2020. [DOI: 10.1080/15627020.2020.1779613] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Beaven Utete
- Department of Wildlife Ecology and Conservation, Chinhoyi University of Technology, Chinhoyi, Zimbabwe
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12
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Pausas JG, Bond WJ. On the Three Major Recycling Pathways in Terrestrial Ecosystems. Trends Ecol Evol 2020; 35:767-775. [PMID: 32381268 DOI: 10.1016/j.tree.2020.04.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/03/2020] [Accepted: 04/09/2020] [Indexed: 12/27/2022]
Abstract
Plants are the largest biomass component of most terrestrial ecosystems, and litter decomposition is considered the dominant process by which nutrients return to plants. We show that in terrestrial ecosystems, there are three major pathways by which plant biomass is degraded into forms that release nutrients again available to plants: microbial decomposition; vertebrate herbivory; and wildfires. These processes act at different spatial and temporal scales, have different niches, and generates different ecological and evolutionary feedbacks. This holistic view in which microbes, herbivores, and wildfires play a joint role in the functioning of ecosystems contributes to a better understanding of the diversity of mechanisms regulating the biosphere.
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Affiliation(s)
- Juli G Pausas
- Centro de Investigaciones sobre Desertificación (CIDE-CSIC), Valencia, Spain.
| | - William J Bond
- Department of Biological Sciences, University of Cape Town, Cape Town, South Africa; South African Environmental Observation Network, National Research Foundation, Claremont, South Africa
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13
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Mapping Kenyan Grassland Heights Across Large Spatial Scales with Combined Optical and Radar Satellite Imagery. REMOTE SENSING 2020. [DOI: 10.3390/rs12071086] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Grassland monitoring can be challenging because it is time-consuming and expensive to measure grass condition at large spatial scales. Remote sensing offers a time- and cost-effective method for mapping and monitoring grassland condition at both large spatial extents and fine temporal resolutions. Combinations of remotely sensed optical and radar imagery are particularly promising because together they can measure differences in moisture, structure, and reflectance among land cover types. We combined multi-date radar (PALSAR-2 and Sentinel-1) and optical (Sentinel-2) imagery with field data and visual interpretation of aerial imagery to classify land cover in the Masai Mara National Reserve, Kenya using machine learning (Random Forests). This study area comprises a diverse array of land cover types and changes over time due to seasonal changes in precipitation, seasonal movements of large herds of resident and migratory ungulates, fires, and livestock grazing. We classified twelve land cover types with user’s and producer’s accuracies ranging from 66%–100% and an overall accuracy of 86%. These methods were able to distinguish among short, medium, and tall grass cover at user’s accuracies of 83%, 82%, and 85%, respectively. By yielding a highly accurate, fine-resolution map that distinguishes among grasses of different heights, this work not only outlines a viable method for future grassland mapping efforts but also will help inform local management decisions and research in the Masai Mara National Reserve.
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Shurin JB, Aranguren-Riaño N, Duque Negro D, Echeverri Lopez D, Jones NT, Laverde-R O, Neu A, Pedroza Ramos A. Ecosystem effects of the world's largest invasive animal. Ecology 2020; 101:e02991. [PMID: 31994172 DOI: 10.1002/ecy.2991] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/04/2019] [Indexed: 11/06/2022]
Abstract
The keystone roles of mega-fauna in many terrestrial ecosystems have been lost to defaunation. Large predators and herbivores often play keystone roles in their native ranges, and some have established invasive populations in new biogeographic regions. However, few empirical examples are available to guide expectations about how mega-fauna affect ecosystems in novel environmental and evolutionary contexts. We examined the impacts on aquatic ecosystems of an emerging population of hippopotamus (Hippopotamus amphibus) that has been growing in Colombia over the last 25 yr. Hippos in Africa fertilize lakes and rivers by grazing on land and excreting wastes in the water. Stable isotopes indicate that terrestrial sources contribute more carbon in Colombian lakes containing hippo populations, and daily dissolved oxygen cycles suggest that their presence stimulates ecosystem metabolism. Phytoplankton communities were more dominated by cyanobacteria in lakes with hippos, and bacteria, zooplankton, and benthic invertebrate communities were similar regardless of hippo presence. Our results suggest that hippos recapitulate their role as ecosystem engineers in Colombia, importing terrestrial organic matter and nutrients with detectable impacts on ecosystem metabolism and community structure in the early stages of invasion. Ongoing range expansion may pose a threat to water resources.
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Affiliation(s)
- Jonathan B Shurin
- Section of Ecology, Behavior and Evolution, University of California San Diego, La Jolla, California, 92093-0116, USA
| | - Nelson Aranguren-Riaño
- Unidad de Ecología en Sistemas Acuáticos-UDESA, Universidad Pedagógica y Tecnológica de Colombia, Avenida Central del Norte 39-115, Tunja, Boyacá, Colombia
| | - Daniel Duque Negro
- Unidad de Ecología en Sistemas Acuáticos-UDESA, Universidad Pedagógica y Tecnológica de Colombia, Avenida Central del Norte 39-115, Tunja, Boyacá, Colombia
| | - David Echeverri Lopez
- Corporación Autónoma Regional de las Cuencas de los Ríos Negros y Nare-CORNARE, Calle 13, No. 9-29, Municipio de la Unión, Antioquia, Colombia
| | - Natalie T Jones
- Section of Ecology, Behavior and Evolution, University of California San Diego, La Jolla, California, 92093-0116, USA.,School of Biological Sciences, The University of Queensland, St. Lucia, Queensland, 4072, Australia
| | - Oscar Laverde-R
- Departamento de Biología, Facultad de Ciencias, Pontificia Universidad Javeriana, Sede Bogotá, D.C., Colombia
| | - Alexander Neu
- Section of Ecology, Behavior and Evolution, University of California San Diego, La Jolla, California, 92093-0116, USA
| | - Adriana Pedroza Ramos
- Unidad de Ecología en Sistemas Acuáticos-UDESA, Universidad Pedagógica y Tecnológica de Colombia, Avenida Central del Norte 39-115, Tunja, Boyacá, Colombia
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15
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Spatial ecology of male hippopotamus in a changing watershed. Sci Rep 2019; 9:15392. [PMID: 31659224 PMCID: PMC6817855 DOI: 10.1038/s41598-019-51845-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 10/05/2019] [Indexed: 02/07/2023] Open
Abstract
The obligate dependency of the common hippopotamus, Hippopotamus amphibius, on water makes them particularly vulnerable to hydrological disturbances. Despite the threats facing this at-risk species, there is a lack of information regarding H. amphibius spatial ecology. We used high-resolution tracking data of male H. amphibius to assess home range size, movement mode (e.g. residency and migratory movements), and resource selection patterns. We compared these results across seasons to understand how hydrological variability influences H. amphibius movement. Our study watershed has been severely impacted by anthropogenic water abstraction causing the river to stop flowing for prolonged periods. We observed H. amphibius movements to be highly constrained to the river course with grassy floodplains being their preferred habitat. Dominant and small sub-adult males displayed year-round residency in/near river pools and had smaller home ranges compared to large sub-adults. During the dry season, large sub-adult males made significant (~15 km) upstream movements. The larger home range size of large sub-adults can be attributed to the elevated levels of migratory and exploratory activities to limit conspecific aggression as the river dries. Our observations provide insight into how future changes in water flow may influence male H. amphibius movements and populations through density-dependent effects.
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