1
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Gissi E, Goodman MC, Elahi R, McDevitt-Irwin JM, Arnoldi NS, Arafeh-Dalmau N, Knight CJ, Olguín-Jacobson C, Palmisciano M, Tillman CM, De Leo GA, Micheli F. Sex-specific variation in species interactions matters in ecological communities. Trends Ecol Evol 2024:S0169-5347(24)00171-X. [PMID: 39107207 DOI: 10.1016/j.tree.2024.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 06/28/2024] [Accepted: 07/12/2024] [Indexed: 08/09/2024]
Abstract
Understanding how natural communities and ecosystems are structured and respond to anthropogenic pressures in a rapidly changing world is key to successful management and conservation. A fundamental but often overlooked biological characteristic of organisms is sex. Sex-based responses are often considered when conducting studies at organismal and population levels, but are rarely investigated in community ecology. Focusing on kelp forests as a model system, and through a review of other marine and terrestrial ecosystems, we found evidence of widespread sex-based variation in species interactions. Sex-based variation in species interactions is expected to affect ecosystem structure and functioning via multiple trophic and nontrophic pathways. Understanding the drivers and consequences of sex-based variation in species interactions can inform more effective management and restoration.
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Affiliation(s)
- Elena Gissi
- Oceans Department, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA; National Research Council, Institute of Marine Science, Venice, 30122, Italy; National Biodiversity Future Center, Palermo, 90133, Italy.
| | | | - Robin Elahi
- Oceans Department, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - Jamie M McDevitt-Irwin
- Oceans Department, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA; Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA 93117, USA
| | - Natalie S Arnoldi
- Oceans Department, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - Nur Arafeh-Dalmau
- Oceans Department, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA; Department of Geography, University of California Los Angeles, Los Angeles, CA 90095, USA; Centre for Biodiversity and Conservation Science, School of Biological Sciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Christopher J Knight
- Oceans Department, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | | | - Melissa Palmisciano
- Oceans Department, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - Ceyenna M Tillman
- Oceans Department, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - Giulio A De Leo
- Oceans Department, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - Fiorenza Micheli
- Oceans Department, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA; Stanford Center for Ocean Solutions, Stanford University, Pacific Grove, CA 93950, USA
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2
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Rosenblatt AE, Greco R, Beal E, Colbert J, Moore Y, Baglin V, Nifong JC. Golf course living leads to a diet shift for American alligators. Ecol Evol 2023; 13:e10495. [PMID: 37664492 PMCID: PMC10468965 DOI: 10.1002/ece3.10495] [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: 06/22/2023] [Revised: 07/31/2023] [Accepted: 08/11/2023] [Indexed: 09/05/2023] Open
Abstract
Human-driven land use change can fundamentally alter ecological communities, especially the diversity and abundance of large-bodied predators. Yet, despite the important roles large-bodied predators play in structuring communities through feeding, there have been only a few investigations of how the feeding patterns of large-bodied predators change in human-dominated landscapes. One group of large-bodied predators that has been largely overlooked in the context of land use change is the crocodilians. To help fill these gaps, we studied the feeding patterns of juvenile American alligators (Alligator mississippiensis) on neighboring barrier islands on the southeast coast of Georgia, USA. Jekyll Island has multiple golf courses and substantial amounts of human activity, while Sapelo Island does not have any golf courses and a much smaller amount of human activity. We found that juvenile alligator populations on both islands ate the same types of prey but in vastly different quantities. Sapelo Island alligators primarily consumed crustaceans while alligators that lived on Jekyll Island's golf courses ate mostly insects/arachnids. Furthermore, the Jekyll Island alligators exhibited a much more generalist feeding pattern (individuals mostly ate the same types of prey in the same quantities) than the more specialized Sapelo Island alligators (diets were more varied across individuals). The most likely explanation for our results is that alligators living on golf courses have different habitat use patterns and have access to different prey communities relative to alligators in more natural habitats. Thus, land use change can strongly alter the feeding patterns of large-bodied predators and, as a result, may affect their body condition, exposure to human-made chemicals, and role within ecological communities.
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Affiliation(s)
| | - Robert Greco
- University of North FloridaJacksonvilleFloridaUSA
| | - Eli Beal
- University of North FloridaJacksonvilleFloridaUSA
| | | | - Yank Moore
- Jekyll Island AuthorityJekyll IslandGeorgiaUSA
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3
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Pereira AC, Nardoto GB, Colli GR. Sources of intraspecific variation in the isotopic niche of a semi-aquatic predator in a human-modified landscape. PeerJ 2023; 11:e15915. [PMID: 37663285 PMCID: PMC10474837 DOI: 10.7717/peerj.15915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 07/26/2023] [Indexed: 09/05/2023] Open
Abstract
Intraspecific variation modulates patterns of resource use by species, potentially affecting the structure and stability of food webs. In human-modified landscapes, habitat disturbance modifies trophic interactions and intraspecific niche variation, impacting population persistence. Here, we investigated the relationship of sex, ontogeny, and habitat factors with the trophic niche of Caiman crocodilus in an agricultural landscape. We evaluated temporal variation in the trophic niche parameters using carbon and nitrogen stable isotope analysis from different body tissues. We found that caimans exploit the same carbon and nitrogen pools through time, with low isotopic variability between seasons, partly due to the slow isotope turnover rates of tissues in crocodilians. Conversely, the trophic niche of caimans varied across habitats, but with no evidence of a difference between natural and anthropogenic habitats. It apparently results from the influence of habitat suitability, connectivity, and caiman movements during the foraging. Our findings highlight the broader niches of juvenile caimans relative to adults, possibly in response of territorialism and opportunistic foraging strategy. Although using similar resources, females had a larger niche than males, probably associated with foraging strategies during nesting. Considering the sex and body size categories, caimans occupied distinct isotopic regions in some habitats, indicating apparent niche segregation. Ontogenetic trophic shifts in the isotopes (δ13C and δ15N) depended on sex, leading to resource partitioning that can potentially reduce intraspecific competition. Decision-makers and stakeholders should consider the trophic dynamics of sex and body size groups for the sustainable management and conservation of caiman populations, which implies in the maintenance of wetland habitats and landscape heterogeneity in the Formoso River floodplain.
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Affiliation(s)
- André Costa Pereira
- Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasilia, Distrito Federal, Brazil
- Departamento de Ecologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasilia, Distrito Federal, Brazil
| | - Gabriela Bielefeld Nardoto
- Departamento de Ecologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasilia, Distrito Federal, Brazil
| | - Guarino Rinaldi Colli
- Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasilia, Distrito Federal, Brazil
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4
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Kojima LV, Tuberville TD, Parrott BB. Integrating Mercury Concentrations in American Alligators (Alligator mississippiensis) with Hunter Consumption Surveys to Estimate Exposure Risk. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2023; 42:525-534. [PMID: 36636863 PMCID: PMC10107320 DOI: 10.1002/etc.5524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/13/2022] [Accepted: 11/07/2022] [Indexed: 06/17/2023]
Abstract
Mercury is a naturally occurring element but is also considered a widespread contaminant due to global anthropogenic activity. Even in moderate amounts, mercury (Hg) is an established neurotoxin and is associated with a range of adverse outcomes both in humans and wildlife. Humans in the United States are most commonly exposed to Hg through contaminated food or drinking water, and the consumption of game species, particularly those occupying higher trophic levels, has the potential to expose hunters to high concentrations of Hg. In the present study, we determined Hg concentrations in tail muscle and blood from American alligators (Alligator mississippiensis) inhabiting a region (Savannah River Site, SC, USA) with known Hg contamination. We then integrated these data with alligator harvest records and previously published surveys of alligator meat consumption patterns to estimate potential exposure risk. We found that the average Hg concentrations in tail muscle (1.34 mg/kg, wet wt) from sampled alligators exceeded the recommended threshold for Hg exposure based on the World Health Organization's guidelines (0.5 mg/kg, wet wt). In addition, based on regional consumption patterns reported for both adults and children, we estimated Hg exposures ( x ¯ Adult = 0.419 µg/kg/day, x ¯ Child = 2.24 µg/kg/day) occurring well above the US Environmental Protection Agency methylmercury reference dose of 0.1 μg/kg/day. Although the two reservoirs sampled in the present study are not currently open to alligator hunting, they are connected to waters that are publicly accessible, and the extent of alligator mobility across these sites is not known. Together, the findings reported in the present study further demonstrate the need for active monitoring of Hg concentrations in game species, which can convey substantial exposure risks to the public. Environ Toxicol Chem 2023;42:525-534. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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Affiliation(s)
- Laura V. Kojima
- Savannah River Ecology LaboratoryUniversity of GeorgiaAikenSouth CarolinaUSA
- Eugene P. Odum School of EcologyUniversity of GeorgiaAthensGeorgiaUSA
| | - Tracey D. Tuberville
- Savannah River Ecology LaboratoryUniversity of GeorgiaAikenSouth CarolinaUSA
- Warnell School of Forestry and Natural ResourcesUniversity of GeorgiaAthensGeorgiaUSA
| | - Benjamin B. Parrott
- Savannah River Ecology LaboratoryUniversity of GeorgiaAikenSouth CarolinaUSA
- Eugene P. Odum School of EcologyUniversity of GeorgiaAthensGeorgiaUSA
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5
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Kruis F, Wallwork M, Spain M, Rosenblatt AE. American alligator (Alligator mississippiensis) weight gain in captivity and implications for captive reptile body condition. Zoo Biol 2023; 42:107-111. [PMID: 35815697 DOI: 10.1002/zoo.21721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 02/02/2022] [Accepted: 06/22/2022] [Indexed: 11/09/2022]
Abstract
The body condition of an animal is an indicator of health status and is dependent upon many factors, some of which can vary between wild and captive settings. Despite this, there have not been many studies on how captivity affects body condition relative to wild animal populations. This study explores the body condition of captive and wild American alligators (Alligator mississippiensis) because reptiles are frequently overlooked in studies of captive animal health and because alligators are well-represented in captivity. We collected body condition data from 209 captive alligators and 935 wild alligators throughout Florida and southeastern Georgia and compared the relationships between body condition and body length for each group. We found that captive alligators exhibited significantly higher body condition values as they aged, and that this result was driven by the difference between captive and wild males. Body condition values for captive juveniles did not differ from wild juveniles, but they differed when comparing adults. Our results suggest that factors such as diet and movement rates play major roles in determining alligator body condition and that body condition may be an important metric for monitoring captive alligator health, especially for older adult males.
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Affiliation(s)
- Faith Kruis
- Biology Department, University of North Florida, Jacksonville, Florida, USA
| | - Madison Wallwork
- Biology Department, University of North Florida, Jacksonville, Florida, USA
| | - Marisa Spain
- Biology Department, University of North Florida, Jacksonville, Florida, USA.,Jacksonville Zoo and Gardens, Jacksonville, Florida, USA
| | - Adam E Rosenblatt
- Biology Department, University of North Florida, Jacksonville, Florida, USA
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6
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Lawson AJ, Jodice PGR, Rainwater TR, Dunham KD, Hart M, Butfiloski JW, Wilkinson PM, McFadden KW, Moore CT. Hidden in plain sight: Integrated population models to resolve partially observable latent population structure. Ecosphere 2022. [DOI: 10.1002/ecs2.4321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Abigail J. Lawson
- Department of Forestry and Environmental Conservation Clemson University Clemson South Carolina USA
| | - Patrick G. R. Jodice
- U.S. Geological Survey, South Carolina Cooperative Fish and Wildlife Research Unit Clemson University Clemson South Carolina USA
| | - Thomas R. Rainwater
- Department of Forestry and Environmental Conservation Clemson University Clemson South Carolina USA
- Baruch Institute of Coastal Ecology and Forest Science Clemson University Georgetown South Carolina USA
- Tom Yawkey Wildlife Center Georgetown South Carolina USA
| | - Kylee D. Dunham
- U.S. Geological Survey, Eastern Ecological Science Center Laurel Maryland USA
| | - Morgan Hart
- South Carolina Department of Natural Resources Columbia South Carolina USA
| | | | | | - K. W. McFadden
- U.S. Geological Survey, South Carolina Cooperative Fish and Wildlife Research Unit Clemson University Clemson South Carolina USA
| | - Clinton T. Moore
- U.S. Geological Survey, Georgia Cooperative Fish and Wildlife Research Unit, Warnell School of Forestry and Natural Resources University of Georgia Athens Georgia USA
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7
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Campbell MA, Udyawer V, Jardine TD, Fukuda Y, Kopf RK, Bunn SE, Campbell HA. Dietary shifts may underpin the recovery of a large carnivore population. Biol Lett 2022; 18:20210676. [PMID: 35472283 PMCID: PMC9042529 DOI: 10.1098/rsbl.2021.0676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Supporting the recovery of large carnivores is a popular yet challenging endeavour. Estuarine crocodiles in Australia are a large carnivore conservation success story, with the population having extensively recovered from past heavy exploitation. Here, we explored if dietary changes had accompanied this large population recovery by comparing the isotopes δ13C and δ15N in bones of crocodiles sampled 40 to 55 years ago (small population) with bones from contemporary individuals (large population). We found that δ13C and δ15N values were significantly lower in contemporary crocodiles than in the historical cohort, inferring a shift in prey preference away from marine and into terrestrial food webs. We propose that an increase in intraspecific competition within the recovering crocodile population, alongside an increased abundance of feral ungulates occupying the floodplains, may have resulted in the crocodile population shifting to feed predominantly upon terrestrial food sources. The number of feral pigs consumed to sustain and grow crocodile biomass may help suppress pig population growth and increase the flow of terrestrially derived nutrients into aquatic ecosystems. The study highlights the significance of prey availability in contributing to large carnivore population recovery.
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Affiliation(s)
- Mariana A Campbell
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and Environment, Charles Darwin University, Darwin, NT, Australia
| | - Vinay Udyawer
- Australian Institute of Marine Science, Darwin, NT, Australia
| | - Timothy D Jardine
- School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK, Canada.,Australian Rivers Institute, Griffith University, Nathan, QLD, Australia
| | - Yusuke Fukuda
- Department of Environment, Parks and Water Security, Darwin, NT, Australia
| | - R Keller Kopf
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and Environment, Charles Darwin University, Darwin, NT, Australia
| | - Stuart E Bunn
- Australian Rivers Institute, Griffith University, Nathan, QLD, Australia
| | - Hamish A Campbell
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and Environment, Charles Darwin University, Darwin, NT, Australia
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8
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Long-distance, synchronized and directional fall movements suggest migration in Arctic hares on Ellesmere Island (Canada). Sci Rep 2022; 12:5003. [PMID: 35322061 PMCID: PMC8943133 DOI: 10.1038/s41598-022-08347-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 03/04/2022] [Indexed: 11/08/2022] Open
Abstract
Animal migration contributes largely to the seasonal dynamics of High Arctic ecosystems, linking distant habitats and impacting ecosystem structure and function. In polar deserts, Arctic hares are abundant herbivores and important components of food webs. Their annual migrations have long been suspected, but never confirmed. We tracked 25 individuals with Argos satellite telemetry to investigate the existence of migration in a population living at Alert (Ellesmere Island, Nunavut, Canada). During fall, 21 hares undertook directional, long-distance movements in a southwestern direction towards Lake Hazen. Daily movement rates averaged 1.3 ± 0.5 km, 4.3 ± 1.6 km, and 1.7 ± 0.9 km before, during, and after relocation, respectively. Straight-line and minimum cumulative distances traveled averaged 98 ± 18 km (range: 72-148 km) and 198 ± 62 km (range: 113-388 km), respectively. This is the first report of large-scale seasonal movements in Arctic hares and, surprisingly, in any lagomorph species. These movements may be part of an annual migratory pattern. Our results redefine our understanding of the spatial ecology of Arctic hares, demonstrate unsuspected mobility capacities in lagomorphs, and open new perspectives regarding the ecological dynamics of the northern polar deserts.
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9
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Smith GP, Gardner J, Gibbs J, Griswold T, Hauser M, Yanega D, Ponisio LC. Sex‐associated differences in the network roles of pollinators. Ecosphere 2021. [DOI: 10.1002/ecs2.3863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Gordon P. Smith
- Department of Neurobiology and Behavior Cornell University W361 Mudd Hall, 215 Tower Road Ithaca New York 14853 USA
- Department of Biology Institute of Ecology and Evolution University of Oregon 272 Onyx Bridge Eugene Oregon 97403 USA
- Department of Entomology University of California, Riverside 417 Entomology Bldg. Riverside California 92521 USA
| | - Joel Gardner
- Department of Entomology University of Manitoba 12 Dafoe Road Winnipeg Manitoba Canada
| | - Jason Gibbs
- Department of Entomology University of Manitoba 12 Dafoe Road Winnipeg Manitoba Canada
| | - Terry Griswold
- USDA‐ARS Pollinating Insects Research Unit Utah State University 1410 North 800 East Logan Utah 84322 USA
| | - Martin Hauser
- Plant Pest Diagnostics Branch California Department of Food and Agriculture 3294 Meadowview Road Sacramento California 95832 USA
| | - Doug Yanega
- Department of Entomology University of California, Riverside 417 Entomology Bldg. Riverside California 92521 USA
| | - Lauren C. Ponisio
- Department of Biology Institute of Ecology and Evolution University of Oregon 272 Onyx Bridge Eugene Oregon 97403 USA
- Department of Entomology University of California, Riverside 417 Entomology Bldg. Riverside California 92521 USA
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10
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Jory C, Lesage V, Leclerc A, Giard J, Iverson S, Bérubé M, Michaud R, Nozais C. Individual and population dietary specialization decline in fin whales during a period of ecosystem shift. Sci Rep 2021; 11:17181. [PMID: 34433851 PMCID: PMC8387503 DOI: 10.1038/s41598-021-96283-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 07/28/2021] [Indexed: 11/25/2022] Open
Abstract
This study sought to estimate the effect of an anthropogenic and climate-driven change in prey availability on the degree of individual and population specialization of a large marine predator, the fin whale (Balaenoptera physalus). We examined skin biopsies from 99 fin whales sampled in the St. Lawrence Estuary (Canada) over a nine year period (1998–2006) during which environmental change was documented. We analyzed stable isotope ratios in skin and fatty acid signatures in blubber samples of whales, as well as in seven potential prey species, and diet was quantitatively assessed using Bayesian isotopic models. An abrupt change in fin whale dietary niche coincided with a decrease in biomass of their predominant prey, Arctic krill (Thysanoessa spp.). This dietary niche widening toward generalist diets occurred in nearly 60% of sampled individuals. The fin whale population, typically composed of specialists of either krill or lipid-rich pelagic fishes, shifted toward one composed either of krill specialists or true generalists feeding on various zooplankton and fish prey. This change likely reduced intraspecific competition. In the context of the current “Atlantification” of northern water masses, our findings emphasize the importance of considering individual-specific foraging tactics and not only population or group average responses when assessing population resilience or when implementing conservation measures.
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Affiliation(s)
- Cabrol Jory
- Maurice Lamontagne Institute, Fisheries and Oceans Canada, Mont-Joli, QC, Canada.
| | - Véronique Lesage
- Maurice Lamontagne Institute, Fisheries and Oceans Canada, Mont-Joli, QC, Canada.,Département de Biologie, Chimie et Géographie, Québec-Océan, Université du Québec à Rimouski, Rimouski, QC, Canada
| | - Alexandra Leclerc
- Maurice Lamontagne Institute, Fisheries and Oceans Canada, Mont-Joli, QC, Canada.,Département de Biologie, Chimie et Géographie, Québec-Océan, Université du Québec à Rimouski, Rimouski, QC, Canada
| | - Janie Giard
- Groupe de Recherche et d'Éducation sur les Mammifères Marins, Tadoussac, QC, Canada
| | - Sara Iverson
- Department of Biology, Dalhousie University, Halifax, NS, Canada
| | - Martine Bérubé
- Marine Evolution and Conservation, Groningen Institute of Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.,Centre for Coastal Studies, Provincetown, MA, USA
| | - Robert Michaud
- Groupe de Recherche et d'Éducation sur les Mammifères Marins, Tadoussac, QC, Canada
| | - Christian Nozais
- Département de Biologie, Chimie et Géographie, Québec-Océan, Université du Québec à Rimouski, Rimouski, QC, Canada
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11
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Correlations between environmental salinity levels, blood biochemistry parameters, and steroid hormones in wild juvenile American alligators (Alligator mississippiensis). Sci Rep 2021; 11:15168. [PMID: 34312414 PMCID: PMC8313683 DOI: 10.1038/s41598-021-94557-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/13/2021] [Indexed: 02/07/2023] Open
Abstract
American alligators (Alligator mississippiensis) inhabit freshwater wetlands that are vulnerable to salinization caused by anthropogenic alterations to freshwater flow, in addition to storm surges, sea level rise, and droughts. Salinization of coastal freshwater habitats is a growing concern in a changing climate due to increased frequency and intensity of storm surges and drought conditions. This study opportunistically sampled juvenile male and female wild alligators in various salinities each month excluding November, December, and January for one year at Rockefeller Wildlife Refuge in coastal Louisiana. Blood plasma biochemistry parameters including electrolyte levels were subsequently measured. In addition, levels of various renin-angiotensin-aldosterone system hormones, glucocorticoids, androgens, estrogens, and progestogens were analyzed using liquid chromatography and tandem mass spectrometry. Only males were sampled in hyperosmotic environments (> 10‰) during dry conditions in late summer 2018. In juvenile males, plasma Na+, Cl-, and the progestogen 17α,20β-dihydroxypregnenone were significantly and positively correlated with environmental salinity. However, variation in glucocorticoids, androgens, and estrogens were not associated with hypersaline water while sex steroids showed significant seasonal variation. This study demonstrated significant correlation of environmental salinity with electrolyte levels and a sex steroid in wild juvenile alligators, and to our knowledge represents the first measurement of 17α,20β-dihydroxypregnenone in alligators.
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12
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Ward‐Fear G, Shine R, Brown GP. Within‐population variation in dietary traits: implications for vulnerability and impact of imperiled keystone predators. Ecosphere 2020. [DOI: 10.1002/ecs2.3136] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- G. Ward‐Fear
- School of Life and Environmental Sciences University of Sydney Sydney New South Wales 2006 Australia
- Department of Biological Sciences Macquarie University Sydney New South Wales 2109 Australia
| | - R. Shine
- School of Life and Environmental Sciences University of Sydney Sydney New South Wales 2006 Australia
- Department of Biological Sciences Macquarie University Sydney New South Wales 2109 Australia
| | - G. P. Brown
- School of Life and Environmental Sciences University of Sydney Sydney New South Wales 2006 Australia
- Department of Biological Sciences Macquarie University Sydney New South Wales 2109 Australia
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13
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Lawson AJ, Moore CT, Rainwater TR, Nilsen FM, Wilkinson PM, Lowers RH, Guillette LJ, McFadden KW, Jodice PGR. Nonlinear patterns in mercury bioaccumulation in American alligators are a function of predicted age. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 707:135103. [PMID: 31863991 DOI: 10.1016/j.scitotenv.2019.135103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 10/18/2019] [Accepted: 10/19/2019] [Indexed: 06/10/2023]
Abstract
Mercury is a widespread, naturally occurring contaminant that biomagnifies in wetlands due to the methylation of this element by sulfate-reducing bacteria. Species that feed at the top trophic level within wetlands are predicted to have higher mercury loads compared to species feeding at lower trophic levels and are therefore often used for mercury biomonitoring. However, mechanisms for mercury bioaccumulation in sentinel species are often poorly understood, due to a lack of long-term studies or an inability to differentiate between confounding variables. We examined mercury bioaccumulation patterns in the whole blood of American alligators (Alligator mississippiensis) from a long-term mark-recapture study (1979-2017) in South Carolina, USA. Using a growth model and auxiliary information on predicted age at first capture, we differentiated between age- and size-related variation in mercury bioaccumulation, which are often confounded in alligators due to their determinate growth pattern. Contrary to predictions that the oldest or largest individuals were likely to have the highest mercury concentrations, our best-supported model indicated a peak in mercury concentration at 30-40 years of age, depending on the sex, and lower concentrations in the youngest and oldest animals. To evaluate the robustness of our findings, we re-analyzed data from a previously published study of mercury in alligators sampled at Merritt Island National Wildlife Refuge in Florida. Unlike the South Carolina data, the data from Florida contained minimal auxiliary information regarding age, yet the best supported model similarly indicated a peaked rather than increasing relationship between mercury and body size, a less-precise indicator of age. These findings highlight how long-term monitoring can differentiate between confounding variables (e.g., age and size) to better elucidate complex relationships between contaminant exposure and demographic factors in sentinel species.
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Affiliation(s)
- Abigail J Lawson
- Department of Forestry and Environmental Conservation, Clemson University, 261 Lehotsky Hall, Clemson, SC 29634, USA.
| | - Clinton T Moore
- U.S. Geological Survey, Georgia Cooperative Fish and Wildlife Research Unit, Warnell School of Forestry and Natural Resources, University of Georgia, 180 E. Green Street, Athens, GA 30602, USA.
| | - Thomas R Rainwater
- Department of Forestry and Environmental Conservation, Clemson University, 261 Lehotsky Hall, Clemson, SC 29634, USA; Baruch Institute of Coastal Ecology and Forest Science, Clemson University, P.O. Box 596, Georgetown, SC 29442, USA; Tom Yawkey Wildlife Center, 1 Yawkey Way, Georgetown, SC 29440, USA.
| | - Frances M Nilsen
- Department of Obstetrics and Gynecology, Marine Biomedicine and Environmental Science Center, Hollings Marine Laboratory, Medical University of South Carolina, Charleston, SC 29412, USA.
| | | | - Russell H Lowers
- Integrated Mission Support Service (IMSS), Kennedy Space Center, FL 32899, USA.
| | - Louis J Guillette
- Department of Obstetrics and Gynecology, Marine Biomedicine and Environmental Science Center, Hollings Marine Laboratory, Medical University of South Carolina, Charleston, SC 29412, USA
| | - K W McFadden
- U.S. Geological Survey, South Carolina Cooperative Fish and Wildlife Research Unit, 261 Lehotsky Hall, Clemson University, Clemson, SC 29634, USA
| | - Patrick G R Jodice
- U.S. Geological Survey, South Carolina Cooperative Fish and Wildlife Research Unit, 261 Lehotsky Hall, Clemson University, Clemson, SC 29634, USA.
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14
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Somaweera R, Nifong J, Rosenblatt A, Brien ML, Combrink X, Elsey RM, Grigg G, Magnusson WE, Mazzotti FJ, Pearcy A, Platt SG, Shirley MH, Tellez M, Ploeg J, Webb G, Whitaker R, Webber BL. The ecological importance of crocodylians: towards evidence‐based justification for their conservation. Biol Rev Camb Philos Soc 2020; 95:936-959. [DOI: 10.1111/brv.12594] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 02/20/2020] [Accepted: 02/25/2020] [Indexed: 12/27/2022]
Affiliation(s)
- Ruchira Somaweera
- CSIRO Health and Biosecurity Floreat WA 6014 Australia
- School of Biological Sciences, University of Western Australia Crawley WA 6009 Australia
| | - James Nifong
- IFAS‐Fort Lauderdale Research & Education Center, University of Florida Fort Lauderdale FL 33314 USA
| | - Adam Rosenblatt
- University of North Florida 1 UNF Drive, Jacksonville FL 32224 USA
| | - Mathew L. Brien
- Queensland Parks and WildlifeDepartment of Environment and Science Cairns QLD 4870 Australia
| | - Xander Combrink
- Department of Nature ConservationTshwane University of Technology Pretoria South Africa
| | - Ruth M. Elsey
- Louisiana Department of Wildlife and Fisheries Rockefeller Wildlife Refuge Grand Chenier LA 70643 USA
| | - Gordon Grigg
- School of Biological SciencesUniversity of Queensland St Lucia QLD 4072 Australia
| | - William E. Magnusson
- Coordenação da Biodiversidade, Instituto Nacional da Pesquisas da Amazônia Manaus 69067 Brazil
| | - Frank J. Mazzotti
- Department of Wildlife Ecology and ConservationEverglades Research and Education Center, University of Florida Gainesville FL 32603 USA
| | - Ashley Pearcy
- Section for Ecoinformatics and Biodiversity, Department of BioScienceAarhus University Aarhus Denmark
| | - Steven G. Platt
- Wildlife Conservation Society ‐ Myanmar Program Yangon Myanmar
| | - Matthew H. Shirley
- Tropical Conservation InstituteFlorida International University Miami FL 33181 USA
| | | | - Jan Ploeg
- Australian National Centre for Ocean Resources and Security, Innovation Campus, University of Wollongong Wollongong NSW 2522 Australia
| | - Grahame Webb
- Wildlife Management International Karama NT 0812 Australia
- Research Institute for the Environment and Livelihoods, Charles Darwin University Casuarina NT 0810 Australia
| | - Rom Whitaker
- The Madras Crocodile Bank Trust & Centre for Herpetology Mahabalipuram 603104 India
| | - Bruce L. Webber
- CSIRO Health and Biosecurity Floreat WA 6014 Australia
- School of Biological Sciences, University of Western Australia Crawley WA 6009 Australia
- Western Australian Biodiversity Science Institute Perth WA 6000 Australia
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15
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Silliman BR, Hughes BB, Gaskins LC, He Q, Tinker MT, Read A, Nifong J, Stepp R. Are the ghosts of nature's past haunting ecology today? Curr Biol 2019; 28:R532-R537. [PMID: 29738721 DOI: 10.1016/j.cub.2018.04.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Humans have decimated populations of large-bodied consumers and their functions in most of the world's ecosystems. It is less clear how human activities have affected the diversity of habitats these consumers occupy. Rebounding populations of some predators after conservation provides an opportunity to begin to investigate this question. Recent research shows that following long-term protection, sea otters along the northeast Pacific coast have expanded into estuarine marshes and seagrasses, and alligators on the southeast US coast have expanded into saltwater ecosystems, habitats presently thought beyond their niche space. There is also evidence that seals have expanded into subtropical climates, mountain lions into grasslands, orangutans into disturbed forests and wolves into coastal marine ecosystems. Historical records, surveys of protected areas and patterns of animals moving into habitats that were former hunting hotspots indicate that - rather than occupying them for the first time - many of these animals are in fact recolonizing ecosystems. Recognizing that many large consumers naturally live and thrive across a greater diversity of ecosystems has implications for setting historical baselines for predator diversity within specific habitats, enhancing the resilience of newly colonized ecosystems and for plans to recover endangered species, as a greater range of habitats is available for large consumers as refugia from climate-induced threats.
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Affiliation(s)
- Brian R Silliman
- Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA.
| | - Brent B Hughes
- Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA; Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
| | - Leo C Gaskins
- Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA
| | - Qiang He
- Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA
| | - M Tim Tinker
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA; United States Geological Survey, Western Ecology Research Center, Santa Cruz, CA 95060, USA
| | - Andrew Read
- Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA
| | - James Nifong
- Kansas Cooperative Fish and Wildlife Research Unit, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Rick Stepp
- Department of Anthropology, University of Florida, Gainesville, FL 32605, USA
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16
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Hale MD, Bertucci EM, Rainwater TR, Wilkinson PM, Parrott BB. The impact of maternally derived dioxins on embryonic development and hepatic AHR signaling in a long-lived apex predator. CHEMOSPHERE 2019; 229:489-499. [PMID: 31096085 DOI: 10.1016/j.chemosphere.2019.04.187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 04/23/2019] [Accepted: 04/24/2019] [Indexed: 06/09/2023]
Abstract
Dioxins and related contaminants are highly pervasive in aquatic systems and elicit deleterious effects in exposed organisms. Because dioxins exhibit a proclivity to bioaccumulate, long-lived predatory species are particularly vulnerable to their persistence in the environment. We have previously reported elevated expression of CYP1A2, a biomarker of dioxin exposure, in American alligator embryos collected from the Tom Yawkey Wildlife Center (YWC). This coastal population inhabits a system with historical dioxin contamination associated with industrial activities. Herein, we utilize ecological attributes of the alligator to address the persistence of dioxins and furans in yolk and their potential to drive changes in hepatic function. Specifically, we assess variation in expression of AHR signaling components in embryos and its connection to contaminant levels in matched yolk samples. Compared to a reference population, TEQ levels and total penta-, hexa-, octa-substituted CDDs were elevated at YWC. Contrary to predictions, TEQ levels were not significantly related to hepatic AHR1B or CYP1A2 expression. However, a significant association was detected between expression of both factors and embryo:yolk mass ratios, wherein decreasing embryo mass was negatively associated with CYP1A2 but positively associated with AHR1B. These findings suggest that variation in embryonic metabolism and developmental progression likely influence AHR signaling and dioxin toxicity in alligators and potentially other oviparous species. While dioxin concentrations observed in alligators in this study are lower than historical values reported for other wildlife species inhabiting this system, they indicate the continued presence and possible long-term influence of these contaminants in a high trophic status species.
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Affiliation(s)
- Matthew D Hale
- Savannah River Ecology Laboratory Laboratory, Aiken, SC, USA; Odum School of Ecology, University of Georgia, Athens, GA, USA.
| | - Emily M Bertucci
- Savannah River Ecology Laboratory Laboratory, Aiken, SC, USA; Odum School of Ecology, University of Georgia, Athens, GA, USA
| | - Thomas R Rainwater
- Tom Yawkey Wildlife Center Heritage Preserve, South Carolina Department of Natural Resources, Georgetown, SC, USA; Belle W. Baruch Institute of Coastal Ecology and Forest Science, Clemson University, Georgetown, SC, USA
| | - Philip M Wilkinson
- Tom Yawkey Wildlife Center Heritage Preserve, South Carolina Department of Natural Resources, Georgetown, SC, USA
| | - Benjamin B Parrott
- Savannah River Ecology Laboratory Laboratory, Aiken, SC, USA; Odum School of Ecology, University of Georgia, Athens, GA, USA
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17
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Arrizabalaga‐Escudero A, Merckx T, García‐Baquero G, Wahlberg N, Aizpurua O, Garin I, Goiti U, Aihartza J. Trait‐based functional dietary analysis provides a better insight into the foraging ecology of bats. J Anim Ecol 2019; 88:1587-1600. [DOI: 10.1111/1365-2656.13055] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 05/13/2019] [Accepted: 05/31/2019] [Indexed: 11/29/2022]
Affiliation(s)
- Aitor Arrizabalaga‐Escudero
- Department of Zoology and Animal Cell Biology, Faculty of Science and Technology University of the Basque Country UPV/EHU Leioa The Basque Country
| | - Thomas Merckx
- Behavioural Ecology and Conservation Group, Biodiversity Research Centre, Earth and Life Institute UCLouvain Louvain‐La‐Neuve Belgium
- Department of Ecology and Genetics University of Oulu Oulu Finland
| | - Gonzalo García‐Baquero
- Department of Plant Biology and Ecology, Faculty of Science and Technology University of the Basque Country UPV/EHU Leioa The Basque Country
| | | | - Ostaizka Aizpurua
- Section for Evolutionary Genomics University of Copenhagen Copenhagen Denmark
| | - Inazio Garin
- Department of Zoology and Animal Cell Biology, Faculty of Science and Technology University of the Basque Country UPV/EHU Leioa The Basque Country
| | - Urtzi Goiti
- Department of Zoology and Animal Cell Biology, Faculty of Science and Technology University of the Basque Country UPV/EHU Leioa The Basque Country
| | - Joxerra Aihartza
- Department of Zoology and Animal Cell Biology, Faculty of Science and Technology University of the Basque Country UPV/EHU Leioa The Basque Country
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18
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Cullen TM, Longstaffe FJ, Wortmann UG, Goodwin MB, Huang L, Evans DC. Stable isotopic characterization of a coastal floodplain forest community: a case study for isotopic reconstruction of Mesozoic vertebrate assemblages. ROYAL SOCIETY OPEN SCIENCE 2019; 6:181210. [PMID: 30891263 PMCID: PMC6408390 DOI: 10.1098/rsos.181210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 01/04/2019] [Indexed: 06/09/2023]
Abstract
Stable isotopes are powerful tools for elucidating ecological trends in extant vertebrate communities, though their application to Mesozoic ecosystems is complicated by a lack of extant isotope data from comparable environments/ecosystems (e.g. coastal floodplain forest environments, lacking significant C4 plant components). We sampled 20 taxa across a broad phylogenetic, body size, and physiological scope from the Atchafalaya River Basin of Louisiana as an environmental analogue to the Late Cretaceous coastal floodplains of North America. Samples were analysed for stable carbon, oxygen and nitrogen isotope compositions from bioapatite and keratin tissues to test the degree of ecological resolution that can be determined in a system with similar environmental conditions, and using similar constraints, as those in many Mesozoic assemblages. Isotopic results suggest a broad overlap in resource use among taxa and considerable terrestrial-aquatic interchange, highlighting the challenges of ecological interpretation in C3 systems, particularly when lacking observational data for comparison. We also propose a modified oxygen isotope-temperature equation that uses mean endotherm and mean ectotherm isotope data to more precisely predict temperature when compared with measured Atchafalaya River water data. These results provide a critical isotopic baseline for coastal floodplain forests, and act as a framework for future studies of Mesozoic palaeoecology.
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Affiliation(s)
- T M Cullen
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
- Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada M5S 2C6
| | - F J Longstaffe
- Department of Earth Sciences, The University of Western Ontario, 1151 Richmond Street, London, Ontario, Canada N6A 5B7
| | - U G Wortmann
- Department of Earth Sciences, University of Toronto, 22 Russell Street, Toronto, Ontario, Canada M5S 3B1
| | - M B Goodwin
- University of California Museum of Paleontology, 1101 Valley Life Sciences, Berkeley, CA 94720-4780, USA
| | - L Huang
- Department of Earth Sciences, The University of Western Ontario, 1151 Richmond Street, London, Ontario, Canada N6A 5B7
| | - D C Evans
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
- Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada M5S 2C6
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19
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Yang J, Di W, Liu J, Xing M. Influence of earthworms on the nitrogen transfer of sewage sludge in the vermifilter process. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:30998-31006. [PMID: 30182315 DOI: 10.1007/s11356-018-2966-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 08/14/2018] [Indexed: 06/08/2023]
Abstract
A 6-year laboratory study was conducted to explore the performance of the vermifilter (VF) on reducing sewage sludge. Sewage sludge was found to be reduced significantly in the VF and exhibited a better performance of sludge reduction as compared with the conventional biofilter (BF), which could be traced through the nitrogen-rich organic matter. The nitrogen stable isotope technology was applied to study the matter flow of sewage sludge in the VF process and the influence of earthworms Eisenia fetida on sewage sludge reduction. Results showed that (1) the protein material could be consumed more than the polysaccharide and lipid materials, respectively, in the VF; (2) the presence of earthworms could enhance the consumption capacity of the VF on the protein-rich material of the sewage sludge; (3) earthworms played a leading role on the nitrogen lifting of the sewage sludge, leading to the performance difference of the effluent sludge or biofilm sludge between the VF and BF; (4) in the VF, nitrogen-isotope accumulation in either biofilms or earthworms happened more significantly in the lower layer than in the upper one, while nitrogen transfer of sewage sludge happened more significantly in the upper layer than in the lower one; (5) earthworms improved the feeding environment of organisms (microorganisms in biofilms, moth fly larvae, Limacidaes, and Lymnaeidaes); (6) biofilms, Limacidaes, and moth fly larvae performed better than leeches, Lymnaeidaes, and moth fly adults at nitrogen transfer of sewage sludge.
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Affiliation(s)
- Jian Yang
- Laboratory of Yangtze River Water Environment, Ministry of Education, State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Wanyin Di
- Laboratory of Yangtze River Water Environment, Ministry of Education, State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Jing Liu
- School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, 201418, China
| | - Meiyan Xing
- Laboratory of Yangtze River Water Environment, Ministry of Education, State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
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20
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Stock BC, Jackson AL, Ward EJ, Parnell AC, Phillips DL, Semmens BX. Analyzing mixing systems using a new generation of Bayesian tracer mixing models. PeerJ 2018; 6:e5096. [PMID: 29942712 PMCID: PMC6015753 DOI: 10.7717/peerj.5096] [Citation(s) in RCA: 317] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 06/05/2018] [Indexed: 11/20/2022] Open
Abstract
The ongoing evolution of tracer mixing models has resulted in a confusing array of software tools that differ in terms of data inputs, model assumptions, and associated analytic products. Here we introduce MixSIAR, an inclusive, rich, and flexible Bayesian tracer (e.g., stable isotope) mixing model framework implemented as an open-source R package. Using MixSIAR as a foundation, we provide guidance for the implementation of mixing model analyses. We begin by outlining the practical differences between mixture data error structure formulations and relate these error structures to common mixing model study designs in ecology. Because Bayesian mixing models afford the option to specify informative priors on source proportion contributions, we outline methods for establishing prior distributions and discuss the influence of prior specification on model outputs. We also discuss the options available for source data inputs (raw data versus summary statistics) and provide guidance for combining sources. We then describe a key advantage of MixSIAR over previous mixing model software-the ability to include fixed and random effects as covariates explaining variability in mixture proportions and calculate relative support for multiple models via information criteria. We present a case study of Alligator mississippiensis diet partitioning to demonstrate the power of this approach. Finally, we conclude with a discussion of limitations to mixing model applications. Through MixSIAR, we have consolidated the disparate array of mixing model tools into a single platform, diversified the set of available parameterizations, and provided developers a platform upon which to continue improving mixing model analyses in the future.
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Affiliation(s)
- Brian C Stock
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA
| | - Andrew L Jackson
- Department of Zoology, School of Natural Sciences, University of Dublin, Trinity College, Dublin, Ireland
| | - Eric J Ward
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA
| | - Andrew C Parnell
- School of Mathematics and Statistics, Insight Centre for Data Analytics, University College Dublin, Dublin, Ireland
| | | | - Brice X Semmens
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA
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21
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Estuarine crocodiles in a tropical coastal floodplain obtain nutrition from terrestrial prey. PLoS One 2018; 13:e0197159. [PMID: 29874276 PMCID: PMC5991389 DOI: 10.1371/journal.pone.0197159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 04/27/2018] [Indexed: 11/23/2022] Open
Abstract
The estuarine crocodile (Crocodylus porosus) is one of the largest and most widespread crocodilians in the world. Although considered an apex species, the role of the estuarine crocodile in aquatic foodwebs is poorly understood; we know what crocodiles ingest, but not what nourishes them. In this study, we used a combination of stable isotope measurements (δ13C, δ15N, and δ34S) and direct feeding observations to identify the source of nutrition of estuarine crocodiles in Kakadu National Park, Northern Australia. Our results show that most crocodiles sampled (size 850 – 4200mm, with 76% of them being > 2.5 m) consume a large variety of prey, however a large proportion of their nutrition is derived from terrestrial prey. Introduced species such as water buffaloes (Bubalus bubalis) and pigs (Sus scrofa) could contribute between 53 and 84% to the nutrition of the sampled crocodiles. The isotopic composition of large crocodiles (total length > 3 m) suggested possible increase in marine prey consumption with size (R2 = 0.30; p = 0.005). Additionally, we found crocodiles sampled in the dry season had on average higher terrestrial contributions compared to crocodiles sampled during the wet season (84.1 ± 2.4% versus 55.4 ± 7.0%). Overall, we found that terrestrial prey are important source of nutrition for many crocodiles in this region where introduced herbivorous mammals are abundant.
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22
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Villamarín F, Jardine TD, Bunn SE, Marioni B, Magnusson WE. Body size is more important than diet in determining stable-isotope estimates of trophic position in crocodilians. Sci Rep 2018; 8:2020. [PMID: 29386654 PMCID: PMC5792559 DOI: 10.1038/s41598-018-19918-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 01/04/2018] [Indexed: 11/25/2022] Open
Abstract
The trophic position of a top predator, synonymous with food-chain length, is one of the most fundamental attributes of ecosystems. Stable isotope ratios of nitrogen (δ15N) have been used to estimate trophic position of organisms due to the predictable enrichment of 15N in consumer tissues relative to their diet. Previous studies in crocodilians have found upward ontogenetic shifts in their 'trophic position'. However, such increases are not expected from what is known about crocodilian diets because ontogenetic shifts in diet relate to taxonomic categories of prey rather than shifts to prey from higher trophic levels. When we analysed dietary information from the literature on the four Amazonian crocodilians, ontogenetic shifts in dietary-based trophic position (TPdiet) were minimal, and differed from those estimated using δ15N data (TPSIA). Thus, ontogenetic shifts in TPSIA may result not only from dietary assimilation but also from trophic discrimination factors (TDF or Δ 15N) associated with body size. Using a unique TDF value to estimate trophic position of crocodilians of all sizes might obscure conclusions about ontogenetic shifts in trophic position. Our findings may change the way that researchers estimate trophic position of organisms that show orders of magnitude differences in size across their life span.
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Affiliation(s)
- Francisco Villamarín
- Coordenação de Pesquisas em Biodiversidade, Instituto Nacional de Pesquisas da Amazônia - INPA, Manaus, Brazil.
- Universidad Regional Amazónica - Ikiam, Tena, Ecuador.
| | - Timothy D Jardine
- School of Environment and Sustainability, University of Saskatchewan, Saskatoon, Canada
| | - Stuart E Bunn
- Australian Rivers Institute, Griffith University, Brisbane, Australia
| | - Boris Marioni
- Programa de Pós-Graduação em Biologia de Água Doce e Pesca Interior - INPA, Manaus, Brazil
| | - William E Magnusson
- Coordenação de Pesquisas em Biodiversidade, Instituto Nacional de Pesquisas da Amazônia - INPA, Manaus, Brazil
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23
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Hale MD, Galligan TM, Rainwater TR, Moore BC, Wilkinson PM, Guillette LJ, Parrott BB. AHR and CYP1A expression link historical contamination events to modern day developmental effects in the American alligator. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2017; 230:1050-1061. [PMID: 28764121 DOI: 10.1016/j.envpol.2017.07.065] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 07/16/2017] [Accepted: 07/19/2017] [Indexed: 05/16/2023]
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that initiates a transcriptional pathway responsible for the expression of CYP1A subfamily members, key to the metabolism of xenobiotic compounds. Toxic planar halogenated aromatic hydrocarbons, including dioxin and PCBs, are capable of activating the AHR, and while dioxin and PCB inputs into the environment have been dramatically curbed following strict regulatory efforts in the United States, they persist in the environment and exposures remain relevant today. Little is known regarding the effects that long-term chronic exposures to dioxin or dioxin-like compounds might have on the development and subsequent health of offspring from exposed individuals, nor is much known regarding AHR expression in reptilians. Here, we characterize AHR and CYP1A gene expression in embryonic and juvenile specimen of a long-lived, apex predator, the American alligator (Alligator mississippiensis), and investigate variation in gene expression profiles in offspring collected from sites conveying differential exposures to environmental contaminants. Both age- and tissue-dependent patterning of AHR isoform expression are detected. We characterize two downstream transcriptional targets of the AHR, CYP1A1 and CYP1A2, and describe conserved elements of their genomic architecture. When comparisons across different sites are made, hepatic expression of CYP1A2, a direct target of the AHR, appears elevated in embryos from a site associated with a dioxin point source and previously characterized PCB contamination. Elevated CYP1A2 expression is not persistent, as site-specific variation was absent in juveniles originating from field-collected eggs but reared under lab conditions. Our results illustrate the patterning of AHR gene expression in a long-lived environmental model species, and indicate a potential contemporary influence of historical contamination. This research presents a novel opportunity to link contamination events to critical genetic pathways during embryonic development, and carries significant potential to inform our understanding of potential health effects in wildlife and humans.
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Affiliation(s)
- Matthew D Hale
- Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, United States; Odum School of Ecology, University of Georgia, Athens, GA 30602, United States
| | - Thomas M Galligan
- Marine Biomedicine and Environmental Sciences Program, Hollings Marine Laboratory and the Medical University of South Carolina, Charleston, SC 29412, United States
| | - Thomas R Rainwater
- Tom Yawkey Wildlife Center & Belle W. Baruch Institute of Coastal Ecology and Forest Science, Clemson University, Georgetown, SC 29442, United States
| | - Brandon C Moore
- Department of Biology, Sewanee: the University of the South, Sewanee, TN 37383, United States
| | - Philip M Wilkinson
- Tom Yawkey Wildlife Center Heritage Preserve, South Carolina Department of Natural Resources, Georgetown, SC 29440, United States
| | - Louis J Guillette
- Marine Biomedicine and Environmental Sciences Program, Hollings Marine Laboratory and the Medical University of South Carolina, Charleston, SC 29412, United States
| | - Benjamin B Parrott
- Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, United States; Odum School of Ecology, University of Georgia, Athens, GA 30602, United States.
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24
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Nifong JC, Lowers RH. Reciprocal Intraguild Predation betweenAlligator mississippiensis(American Alligator) and Elasmobranchii in the Southeastern United States. SOUTHEAST NAT 2017. [DOI: 10.1656/058.016.0306] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- James C. Nifong
- Kansas Cooperative Fish and Wildlife Research Unit, Division of Biology, Kansas State University, 104 Ackert Hall, Manhattan, KS 66506
| | - Russell H. Lowers
- Integrated Mission Support Services, Mail code IM-300, Kennedy Space Center, FL 32899
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25
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Cloyed CS, Eason PK. Niche partitioning and the role of intraspecific niche variation in structuring a guild of generalist anurans. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170060. [PMID: 28405403 PMCID: PMC5383860 DOI: 10.1098/rsos.170060] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 02/14/2017] [Indexed: 05/30/2023]
Abstract
Intra-population niche differences in generalist foragers have captured the interest of ecologists, because such individuality can have important ecological and evolutionary implications. Few researchers have investigated how these differences affect the relationships among ecologically similar, sympatric species. Using stable isotopes, stomach contents, morphology and habitat preference, we examined niche partitioning within a group of five anurans and determined whether variation within species could facilitate resource partitioning. Species partitioned their niches by trophic level and by foraging habitat. However, there was considerable intraspecific variation in trophic level, with larger individuals generally feeding at higher trophic levels. For species at intermediate trophic levels, smaller individuals overlapped in trophic level with individuals of smaller species and larger individuals overlapped with the smallest individuals from larger species. Species varied in carbon isotopes; species with enriched carbon isotope ratios foraged farther from ponds, whereas species with depleted carbon isotope values foraged closer to ponds. Our study shows that these species partition their niches by feeding at different trophic levels and foraging at different distances from ponds. The intraspecific variation in trophic level decreased the number of individuals from each species that overlapped in trophic level with individuals from other species, which can facilitate species coexistence.
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Affiliation(s)
- Carl S. Cloyed
- National Great Rivers Research and Education Center, East Alton, IL 62024, USA
- Department of Biology, Washington University in St Louis, St Louis, MO 63130, USA
| | - Perri K. Eason
- Department of Biology, University of Louisville, Louisville, KY 40292, USA
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26
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Lai S, Bêty J, Berteaux D. Movement tactics of a mobile predator in a meta-ecosystem with fluctuating resources: the arctic fox in the High Arctic. OIKOS 2016. [DOI: 10.1111/oik.03948] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Sandra Lai
- Canada Research Chair on Northern Biodiversity, Centre for Northern Studies and Quebec Center for Biodiversity Science; Univ. du Québec à Rimouski; 300 Allée des Ursulines Rimouski QC G5L 3A1 Canada
| | - Joël Bêty
- Canada Research Chair on Northern Biodiversity, Centre for Northern Studies and Quebec Center for Biodiversity Science; Univ. du Québec à Rimouski; 300 Allée des Ursulines Rimouski QC G5L 3A1 Canada
| | - Dominique Berteaux
- Canada Research Chair on Northern Biodiversity, Centre for Northern Studies and Quebec Center for Biodiversity Science; Univ. du Québec à Rimouski; 300 Allée des Ursulines Rimouski QC G5L 3A1 Canada
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Skupien GM, Andrews KM, Norton TM. Benefits and biases of VHF and GPS telemetry: A case study of American alligator spatial ecology. WILDLIFE SOC B 2016. [DOI: 10.1002/wsb.697] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Gregory M. Skupien
- Odum School of Ecology; University of Georgia; 140 E Green Street Athens GA 30602 USA
| | - Kimberly M. Andrews
- Savannah River Ecology Laboratory; University of Georgia; SRS Building 737A Aiken SC 29808 USA
| | - Terry M. Norton
- Georgia Sea Turtle Center; Jekyll Island Authority; 214 Stable Road Jekyll Island GA 31527 USA
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28
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Ecological allometries and niche use dynamics across Komodo dragon ontogeny. Naturwissenschaften 2016; 103:27. [DOI: 10.1007/s00114-016-1351-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 12/29/2015] [Accepted: 02/16/2016] [Indexed: 10/22/2022]
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29
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Towner AV, Leos‐Barajas V, Langrock R, Schick RS, Smale MJ, Kaschke T, Jewell OJD, Papastamatiou YP. Sex‐specific and individual preferences for hunting strategies in white sharks. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12613] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alison V. Towner
- Department of Ichthyology and Fisheries Science Rhodes University PO Box 94 Grahamstown 6140 South Africa
- Dyer Island Conservation Trust Geelbek Street PO Box 78 Keinbaai South Africa
| | | | - Roland Langrock
- Centre for Research into Ecological & Environmental Modelling and School of Mathematics and Statistics University of St Andrews St Andrews KY16 9LZ UK
- Department of Business Administration and Economics Bielefeld University PO Box 100131 33501 Bielefeld Germany
| | - Robert S. Schick
- Centre for Research into Ecological & Environmental Modelling and School of Mathematics and Statistics University of St Andrews St Andrews KY16 9LZ UK
| | - Malcolm J. Smale
- Port Elizabeth Museum at Bayworld PO Box 13147 Humewood 6013 South Africa
- Department of Zoology Nelson Mandela Metropolitan University PO Box 77000 Port Elizabeth South Africa
| | - Tami Kaschke
- Dyer Island Conservation Trust Geelbek Street PO Box 78 Keinbaai South Africa
- Department of Management University of Nebraska Lincoln NEUSA
| | - Oliver J. D. Jewell
- Dyer Island Conservation Trust Geelbek Street PO Box 78 Keinbaai South Africa
- Department of Zoology & Entomology University of Pretoria Private Bag X20 Hatfield Pretoria South Africa
- Department of Spatial Ecology Royal Netherlands Institute for Sea Research (NIOZ) Yerseke 4401 NT The Netherlands
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30
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Boggs ASP, Hamlin HJ, Nifong JC, Kassim BL, Lowers RH, Galligan TM, Long SE, Guillette LJ. Urinary iodine and stable isotope analysis to examine habitat influences on thyroid hormones among coastal dwelling American alligators. Gen Comp Endocrinol 2016; 226:5-13. [PMID: 26684734 PMCID: PMC4778256 DOI: 10.1016/j.ygcen.2015.12.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 10/20/2015] [Accepted: 12/08/2015] [Indexed: 11/29/2022]
Abstract
The American alligator, generally a freshwater species, is known to forage in marine environments despite the lack of a salt secreting gland found in other crocodylids. Estuarine and marine foraging could lead to increased dietary uptake of iodine, a nutrient necessary for the production of thyroid hormones. To explore the influence of dietary iodine on thyroid hormone health of coastal dwelling alligators, we described the seasonal plasma thyroxine and triiodothyronine concentrations measured by radioimmunoassay and urinary iodine (UI) concentrations measured by inductively coupled plasma mass spectrometry. We also analyzed long-term dietary patterns through stable isotope analysis of scute tissue. Snout-to-vent length (SVL) was a significant factor among UI and stable isotope analyses. Large adult males greater than 135cm SVL had the highest UI concentrations but did not display seasonality of thyroid hormones. Alligators under 135 SVL exhibited seasonality in thyroid hormones and a positive relationship between UI and triiodothyronine concentrations. Isotopic signatures provided supporting evidence that large males predominantly feed on marine/estuarine prey whereas females showed reliance on freshwater/terrestrial prey supplemented by marine/estuarine prey. UI measurement provided immediate information that correlated to thyroid hormone concentrations whereas stable isotope analysis described long-term dietary patterns. Both techniques demonstrate that adult alligators in coastal environments are utilizing estuarine/marine habitats, which could alter thyroid hormone physiology.
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Affiliation(s)
- Ashley S P Boggs
- National Institute of Standards and Technology, Environmental Chemical Sciences, 331 Fort Johnson Rd, Charleston, SC 29412, USA; Hollings Marine Laboratory, 331 Fort Johnson Rd, Charleston, SC 29412, USA.
| | - Heather J Hamlin
- University of Maine, School of Marine Sciences, 316 Murray Hall Orono, ME 04469, USA
| | - James C Nifong
- University of Florida, Fisheries and Aquatic Sciences, NW 71st Street, Gainsville, FL 32653, USA
| | - Brittany L Kassim
- National Institute of Standards and Technology, Environmental Chemical Sciences, 331 Fort Johnson Rd, Charleston, SC 29412, USA; Hollings Marine Laboratory, 331 Fort Johnson Rd, Charleston, SC 29412, USA
| | - Russell H Lowers
- National Aeronautics and Space Administration, InoMedic Health Applications Inc., SR 405, Kennedy Space Center, FL 32899, USA
| | - Thomas M Galligan
- Hollings Marine Laboratory, 331 Fort Johnson Rd, Charleston, SC 29412, USA; Medical University of South Carolina, Department of Obstetrics and Gynecology, 331 Fort Johnson Rd, Charleston, SC 29412, USA
| | - Stephen E Long
- National Institute of Standards and Technology, Environmental Chemical Sciences, 331 Fort Johnson Rd, Charleston, SC 29412, USA; Hollings Marine Laboratory, 331 Fort Johnson Rd, Charleston, SC 29412, USA
| | - Louis J Guillette
- Hollings Marine Laboratory, 331 Fort Johnson Rd, Charleston, SC 29412, USA; Medical University of South Carolina, Department of Obstetrics and Gynecology, 331 Fort Johnson Rd, Charleston, SC 29412, USA
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31
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Musseau C, Vincenzi S, Jesenšek D, Cantera I, Boulêtreau S, Santoul F, Crivelli AJ. Direct and indirect effects of environmental factors on dietary niches in size-structured populations of a wild salmonid. Ecosphere 2015. [DOI: 10.1890/es15-00109.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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