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Shipley ON, Matich P, Hussey NE, Brooks AML, Chapman D, Frisk MG, Guttridge AE, Guttridge TL, Howey LA, Kattan S, Madigan DJ, O'Shea O, Polunin NV, Power M, Smukall MJ, Schneider EVC, Shea BD, Talwar BS, Winchester M, Brooks EJ, Gallagher AJ. Energetic connectivity of diverse elasmobranch populations - implications for ecological resilience. Proc Biol Sci 2023; 290:20230262. [PMID: 37040803 PMCID: PMC10089721 DOI: 10.1098/rspb.2023.0262] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 03/08/2023] [Indexed: 04/13/2023] Open
Abstract
Understanding the factors shaping patterns of ecological resilience is critical for mitigating the loss of global biodiversity. Throughout aquatic environments, highly mobile predators are thought to serve as important vectors of energy between ecosystems thereby promoting stability and resilience. However, the role these predators play in connecting food webs and promoting energy flow remains poorly understood in most contexts. Using carbon and nitrogen isotopes, we quantified the use of several prey resource pools (small oceanic forage, large oceanics, coral reef, and seagrass) by 17 species of elasmobranch fishes (n = 351 individuals) in The Bahamas to determine their functional diversity and roles as ecosystem links. We observed remarkable functional diversity across species and identified four major groups responsible for connecting discrete regions of the seascape. Elasmobranchs were responsible for promoting energetic connectivity between neritic, oceanic and deep-sea ecosystems. Our findings illustrate how mobile predators promote ecosystem connectivity, underscoring their functional significance and role in supporting ecological resilience. More broadly, strong predator conservation efforts in developing island nations, such as The Bahamas, are likely to yield ecological benefits that enhance the resilience of marine ecosystems to combat imminent threats such as habitat degradation and climate change.
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Affiliation(s)
| | | | - Nigel E. Hussey
- Department of Integrative Biology, University of Windsor, Ontario, Canada
| | - Annabelle M. L. Brooks
- Cape Eleuthera Institute, Cape Eleuthera, Eleuthera, The Bahamas
- Oceanic Whitetip Shark Consortium, Ellicott City, MD, USA
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | | | - Michael G. Frisk
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, USA
| | | | | | - Lucy A. Howey
- Oceanic Whitetip Shark Consortium, Ellicott City, MD, USA
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Sami Kattan
- Beneath The Waves, PO Box 126, Herndon, VA, USA
| | - Daniel J. Madigan
- Department of Integrative Biology, University of Windsor, Ontario, Canada
| | - Owen O'Shea
- The Center for Ocean Research and Education (CORE), Gregory Town, Eleuthera, The Bahamas
| | - Nicholas V. Polunin
- Department of Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Michael Power
- Department of Biology, University of Waterloo, Ontario, Canada
| | | | | | - Brendan D. Shea
- Beneath The Waves, PO Box 126, Herndon, VA, USA
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, USA
| | - Brendan S. Talwar
- Cape Eleuthera Institute, Cape Eleuthera, Eleuthera, The Bahamas
- Oceanic Whitetip Shark Consortium, Ellicott City, MD, USA
- Department of Biological Sciences, Institute of Environment, Florida International University, Miami, FL, USA
| | | | - Edward J. Brooks
- Cape Eleuthera Institute, Cape Eleuthera, Eleuthera, The Bahamas
- Oceanic Whitetip Shark Consortium, Ellicott City, MD, USA
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Queiroz APN, Araújo MLG, Hussey NE, Lessa RPT. Trophic ecology of three stingrays (Myliobatoidei: Dasyatidae) off the Brazilian north-eastern coast: Habitat use and resource partitioning. JOURNAL OF FISH BIOLOGY 2023; 102:27-43. [PMID: 36153814 DOI: 10.1111/jfb.15226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 09/17/2022] [Indexed: 06/16/2023]
Abstract
Understanding the ecological role of species with overlapping distributions is central to inform ecosystem management. Here we describe the diet, trophic level and habitat use of three sympatric stingrays, Hypanus guttatus, H. marianae and H. berthalutzae, through combined stomach content and stable isotope (δ13 C and δ15 N) analyses. Our integrated approach revealed that H. guttatus is a mesopredator that feeds on a diverse diet of benthic and epibenthic marine and estuarine organisms, principally bivalve molluscs, Alpheus shrimp and teleost fishes. Isotopic data supported movement of this species between marine and estuarine environments. H. berthalutzae is also a marine generalist feeder, but feeds primarily on teleost fishes and cephalopods, and consequently occupies a higher trophic level. In contrast, H. marianae is a mesopredator specialized on shrimps and polychaetas occurring only in the marine environment and occupying a low niche breadth. While niche overlap occurred, the three stingrays utilized the same prey resources at different rates and occupied distinct trophic niches, potentially limiting competition for resources and promoting coexistence. These combined data demonstrate that these three mesopredators perform different ecological roles in the ecosystems they occupy, limiting functional redundancy.
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Affiliation(s)
- Aristóteles Philippe Nunes Queiroz
- Programa de Pós-graduação em Biologia Animal, Universidade Federal de Pernambuco, Recife, Brazil
- Laboratório de Dinâmica de Populações Marinhas - DIMAR, Departamento de Pesca e Aquicultura, Universidade Federal Rural de Pernambuco, Recife, Brazil
| | - Maria Lúcia Góes Araújo
- Laboratório de Dinâmica de Populações Marinhas - DIMAR, Departamento de Pesca e Aquicultura, Universidade Federal Rural de Pernambuco, Recife, Brazil
| | - Nigel E Hussey
- Department of Integrative Biology, University of Windsor, Windsor, Ontario, Canada
| | - Rosângela P T Lessa
- Laboratório de Dinâmica de Populações Marinhas - DIMAR, Departamento de Pesca e Aquicultura, Universidade Federal Rural de Pernambuco, Recife, Brazil
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Energetic consequences of resource use diversity in a marine carnivore. Oecologia 2022; 200:65-78. [PMID: 36165921 DOI: 10.1007/s00442-022-05241-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 08/06/2022] [Indexed: 10/14/2022]
Abstract
Understanding how intraspecific variation in the use of prey resources impacts energy metabolism has strong implications for predicting long-term fitness and is critical for predicting population-to-community level responses to environmental change. Here, we examine the energetic consequences of variable prey resource use in a widely distributed marine carnivore, juvenile sand tiger sharks (Carcharias taurus). We used carbon and nitrogen isotope analysis to identify three primary prey resource pools-demersal omnivores, pelagic forage, and benthic detritivores and estimated the proportional assimilation of each resource using Bayesian mixing models. We then quantified how the utilization of these resource pools impacted the concentrations of six plasma lipids and how this varied by ontogeny. Sharks exhibited variable reliance on two of three predominant prey resource pools: demersal omnivores and pelagic forage. Resource use variation was a strong predictor of energetic condition, whereby individuals more reliant upon pelagic forage exhibited higher blood plasma concentrations of very low-density lipoproteins, cholesterol, and triglycerides. These findings underscore how intraspecific variation in resource use may impact the energy metabolism of animals, and more broadly, that natural and anthropogenically driven fluctuations in prey resources could have longer term energetic consequences.
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Shipley ON, Olin JA, Whiteman JP, Bethea DM, Newsome SD. Bulk and amino acid nitrogen isotopes suggest shifting nitrogen balance of pregnant sharks across gestation. Oecologia 2022; 199:313-328. [PMID: 35718810 DOI: 10.1007/s00442-022-05197-6] [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: 07/16/2021] [Accepted: 05/21/2022] [Indexed: 10/18/2022]
Abstract
Nitrogen isotope (δ15N) analysis of bulk tissues and individual amino acids (AA) can be used to assess how consumers maintain nitrogen balance with broad implications for predicting individual fitness. For elasmobranchs, a ureotelic taxa thought to be constantly nitrogen limited, the isotopic effects associated with nitrogen-demanding events such as prolonged gestation remain unknown. Given the linkages between nitrogen isotope variation and consumer nitrogen balance, we used AA δ15N analysis of muscle and liver tissue collected from female bonnethead sharks (Sphyrna tiburo, n = 16) and their embryos (n = 14) to explore how nitrogen balance may vary across gestation. Gestational stage was a strong predictor of bulk tissue and AA δ15N values in pregnant shark tissues, decreasing as individuals neared parturition. This trend was observed in trophic (e.g., Glx, Ala, Val), source (e.g., Lys), and physiological (e.g., Gly) AAs. Several potential mechanisms may explain these results including nitrogen conservation, scavenging, and bacterially mediated breakdown of urea to free ammonia that is used to synthesize AAs. We observed contrasting patterns of isotopic discrimination in embryo tissues, which generally became enriched in 15N throughout development. This was attributed to greater excretion of nitrogenous waste in more developed embryos, and the role of physiologically sensitive AAs (i.e., Gly and Ser) to molecular processes such as nucleotide synthesis. These findings underscore how AA isotopes can quantify shifts in nitrogen balance, providing unequivocal evidence for the role of physiological condition in driving δ15N variation in both bulk tissues and individual AAs.
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Affiliation(s)
- Oliver N Shipley
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA. .,Beneath the Waves, PO Box 126, Herndon, VA, 20172, USA.
| | - Jill A Olin
- Biological Sciences, Great Lakes Research Center, Michigan Technological University, Houghton, MI, 49931, USA
| | - John P Whiteman
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, 23529, USA
| | - Dana M Bethea
- NOAA Fisheries Southeast Regional Office, Saint Petersburg, FL, 33701, USA
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
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Seasonal patterns in stable isotope and fatty acid profiles of southern stingrays (Hypanus americana) at Stingray City Sandbar, Grand Cayman. Sci Rep 2020; 10:19753. [PMID: 33184444 PMCID: PMC7661509 DOI: 10.1038/s41598-020-76858-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 10/22/2020] [Indexed: 11/24/2022] Open
Abstract
Ecotourism opportunities in the marine environment often rely heavily on provisioning to ensure the viewing of cryptic species by the public. However, intentional feeding of wildlife can impact numerous aspects of an animals’ behavior and ecology. Southern stingrays (Hypanus americana) provisioned at Stingray City Sandbar (SCS) in Grand Cayman have altered diel activity patterns and decreased measures of health. This study looked at seasonal changes in stable isotope (SI) and fatty acid (FA) profiles of provisioned stingrays at SCS. Plasma δ15N was higher in male stingrays (11.86 ± 1.71‰) compared to females (10.70 ± 1.71‰). Lower values for δ15N in males and females were measured in October during low tourist season, suggesting stingrays may be forced to rely on native prey items to supplement the decreased amount of provisioned squid available during this time. Plasma FA profiles were significantly different between sexes and across sampling time points, with FAs 22:6n3, 16:0, 20:5n3, 18:1n3C, 18:0 and 18:1n9T contributing to dissimilarity scores between groups. Dietary FAs primarily contributed to differences between males and females lending further evidence to differences in foraging patterns at SCS, likely due to intraspecific competition. Further, canonical analysis of principal coordinates (CAP) analysis of FA profiles suggest similar diets during peak tourist season and differences in diet between males and females during the low season. This study demonstrates alterations in feeding ecology in stingrays at SCS which is of critical importance for effective management of the SCS aggregation.
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