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Xu M, Pethybridge HR, Li Y. Trophic niche partitioning of five sympatric shark species in the tropical eastern Pacific Ocean revealed by multi-tissue fatty acid analysis. ENVIRONMENTAL RESEARCH 2022; 214:113828. [PMID: 35817163 DOI: 10.1016/j.envres.2022.113828] [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: 03/02/2022] [Revised: 06/30/2022] [Accepted: 07/02/2022] [Indexed: 06/15/2023]
Abstract
Fatty acid (FA) analysis of consumer tissues has recently shown utility in drawing further inferences about trophic niche dynamics of marine predators such as sharks. In this study, we examined liver, plasma, and muscle FAs in five coexisting pelagic sharks (blue (Prionace glauca), silky (Carcharhinus falciformis), bigeye thresher (Alopias superciliosus), pelagic thresher (Alopias pelagicus), and smooth hammerhead (Sphyrna zygaena)) inhabiting the tropical eastern Pacific Ocean. Results showed complex inter- and intra-individual and tissue variation among the five shark species. Based on multivariate analysis of the muscle FAs, P. glauca and C. falciformis have the largest FA niche widths, indicating diverse feeding habits or habitat isolation, whereas A. pelagicus and S. zygaena occupied a narrower niche width, reflecting increased trophic specialization. High percentages of muscle FA niche overlap indicated strong resource competition between S.zygaena and C. falciformis and a degree of dietary isolation by P. glauca. Interpretations of feeding ecology differed based on the analysis of plasma FAs, which could be attributed to higher dietary FA turnover rates. The liver was deemed unsuitable to examine FA niche metrics based on high and unexplained intra-specific variance in liver FAs as well as the unique lipid metabolism in chondrichthyans. Overall, our multi-tissue approach revealed the magnitude of potential competitive interactions among coexisting tropical shark species. It also expanded our understanding of inter-tissue variability and best practices when using FA analysis to estimate trophic niche metrics of sharks.
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Affiliation(s)
- Min Xu
- College of Marine Sciences, Shanghai Ocean University, Shanghai, China
| | - Heidi R Pethybridge
- Oceans and Atmosphere, Commonwealth Scientific and Industrial Research Organization, Hobart, Tasmania, Australia
| | - Yunkai Li
- College of Marine Sciences, Shanghai Ocean University, Shanghai, China; Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, Shanghai, China; National Engineering Research Centre for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China; Key Laboratory of Oceanic Fisheries Exploration, Ministry of Agriculture and Rural Affairs, Shanghai, China.
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Segura-Cobeña E, Alfaro-Shigueto J, Mangel J, Urzua A, Górski K. Stable isotope and fatty acid analyses reveal significant differences in trophic niches of smooth hammerhead Sphyrna zygaena (Carcharhiniformes) among three nursery areas in northern Humboldt Current System. PeerJ 2021; 9:e11283. [PMID: 33981504 PMCID: PMC8071072 DOI: 10.7717/peerj.11283] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 03/24/2021] [Indexed: 11/20/2022] Open
Abstract
Fishery pressure on nursery areas of smooth hammerhead in northern Peruvian coast have become a serious threat to sustainability of this resource. Even though, some management actions focused on conservation of the smooth hammerhead populations were proposed in recent years, their scientific foundations are often limited, and biomass of smooth hammerhead in Peruvian waters continues to decrease. To inform management and conservation, this study aims to evaluate the trophic niche of smooth hammerhead juveniles from three nursery areas in the northern Peruvian coast using stable isotope and fatty acid analyses. First, we compared the environmental characteristics of each nursery area (i.e., sea surface temperature and chlorophyll-a concentration) and concluded that nursery areas differed significantly and consistently in sea surface temperature. Subsequently, we evaluated isotopic composition of carbon and nitrogen and fatty acid profiles of muscle and liver tissues collected from juvenile smooth hammerhead from each nursery area. We found that juvenile smooth hammerhead captured in San José were enriched in heavier 13C and 15N isotopes compared to those captured in Máncora and Salaverry. Furthermore, the broadest isotopic niches were observed in juveniles from Máncora, whereas isotopic niches of juveniles from Salaverry and San José were narrower. This difference is primarily driven by the Humboldt Current System and associated upwelling of cold and nutrient rich water that drives increased primary production in San José and, to a less extent, in Salaverry. Compared to smooth hammerhead juveniles from Máncora, those from San José and Salaverry were characterised by higher essential fatty acid concentrations related to pelagic and migratory prey. We conclude that smooth hammerhead juveniles from three nursery areas in the northern Peruvian coast differ significantly in their trophic niches. Thus, management and conservation efforts should consider each nursery area as a unique juvenile stock associated with a unique ecosystem and recognize the dependence of smooth hammerhead recruitment in San José and Salaverry on the productivity driven by the Humboldt Current System.
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Affiliation(s)
- Eduardo Segura-Cobeña
- Programa de Magister en Ecología Marina, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Concepción, Chile.,ProDelphinus, Lima, Perú
| | - Joanna Alfaro-Shigueto
- ProDelphinus, Lima, Perú.,Carrera de Biología Marina, Facultad de Ciencias Veterinarias y Biológicas, Universidad Cientifica del Sur, Lima, Perú
| | - Jeffrey Mangel
- ProDelphinus, Lima, Perú.,Centre for Ecology and Conservation, School of Biosciences, Cornwall Campus, University of Exeter, Penryn, Cornwall, United Kingdom
| | - Angel Urzua
- Departamento de Ecología, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Concepción, Chile.,Centro de Investigación en Biodiversidad y Ambientes Sustentables (CIBAS), Universidad Católica de la Santísima Concepción, Concepción, Chile
| | - Konrad Górski
- Departamento de Ecología, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Concepción, Chile.,Centro de Investigación en Biodiversidad y Ambientes Sustentables (CIBAS), Universidad Católica de la Santísima Concepción, Concepción, Chile.,Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
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Meyer L, Pethybridge H, Nichols PD, Beckmann C, Huveneers C. Abiotic and biotic drivers of fatty acid tracers in ecology: A global analysis of chondrichthyan profiles. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13328] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Lauren Meyer
- Southern Shark Ecology Group College of Science and Engineering, Flinders University Bedford Park South Australia Australia
| | | | | | | | - Charlie Huveneers
- Southern Shark Ecology Group College of Science and Engineering, Flinders University Bedford Park South Australia Australia
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Connan M, Hall G, Smale M. Effects of pre-treatments on bulk stable isotope ratios in fish samples: A cautionary note for studies comparisons. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:291-302. [PMID: 30414205 DOI: 10.1002/rcm.8344] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 10/28/2018] [Accepted: 10/29/2018] [Indexed: 06/08/2023]
Abstract
RATIONALE Stable isotope analysis (SIA) has revolutionised ecological studies over the past thirty years. One of the major fields where SIA is applied in the marine environment is related to the definition of ecosystem structure and function. With marine top predators such as sharks, SIA is a method of choice because tissue samples can be collected without the sacrifice of the animal. In elasmobranch research, the influence of compounds such as urea, trimethylamine oxide and lipids must be considered when using stable isotopes as ecological markers. Currently, a range of pre-treatments are used to chemically remove these molecules prior to SIA. METHODS This study investigated the impact of eleven commonly used pre-treatments on carbon and nitrogen contents and C:N atomic ratio, as well as carbon and nitrogen SI ratios in elasmobranch tissues and its prey, measured by isotope ratio mass spectrometry. Three tissues were tested: blood and muscle of the ragged-tooth shark Carcharias taurus, and muscle of one teleost species, the Cape knifejaw Oplegnathus conwayi. RESULTS Compared with untreated samples, no trend or generalisation could be highlighted with the influence of pre-treatments being species-, tissue- and chemical-element-dependent. For the δ13 C and δ15 N values, differences among pre-treatments were as high as 3‰, therefore potentially leading to erroneous ecological interpretation. CONCLUSIONS The chemical properties of compounds (e.g. urea, lipids) combined with the polarity of solutions (e.g. water, solvents) explained a large part of these observations. This study highlights that pre-treatments need to be considered especially when comparing carbon and nitrogen stable isotope ratios between studies. The results of this study provide a call to all stable isotope researchers to make a concerted effort to standardise pre-treatment methods. This is crucial as global reviews are becoming increasingly more informative.
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Affiliation(s)
- Maëlle Connan
- Institute for Coastal and Marine Research, Marine Apex Predator Research Unit, Department of Zoology, Nelson Mandela University, PO Box 77000, Port Elizabeth, 6031, South Africa
| | - Grant Hall
- UP Stable Isotope Laboratory, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Malcolm Smale
- Institute for Coastal and Marine Research, Marine Apex Predator Research Unit, Department of Zoology, Nelson Mandela University, PO Box 77000, Port Elizabeth, 6031, South Africa
- Port Elizabeth Museum, PO Box 13147 Humewood, Port Elizabeth, 6013, South Africa
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McKinney MA, Dean K, Hussey NE, Cliff G, Wintner SP, Dudley SFJ, Zungu MP, Fisk AT. Global versus local causes and health implications of high mercury concentrations in sharks from the east coast of South Africa. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 541:176-183. [PMID: 26409147 DOI: 10.1016/j.scitotenv.2015.09.074] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/11/2015] [Accepted: 09/15/2015] [Indexed: 06/05/2023]
Abstract
Conservation concern regarding the overharvest of global shark populations for meat and fin consumption largely surrounds documented deleterious ecosystem effects, but may be further supported by improved knowledge of possibly high levels in their edible tissues (particularly meat) of the neurotoxin, methylmercury (CH3Hg). For many regions, however, little data exist on shark tissue Hg concentrations, and reasons for Hg variation within and among species or across regions are poorly understood. We quantified total Hg (THg) in 17 shark species (total n=283) from the east coast of South Africa, a top Hg emitter globally. Concentrations varied from means of around 0.1 mg kg(-1) dry weight (dw) THg in hardnose smoothhound (Mustelus mosis) and whale (Rhincodon typus) sharks to means of over 10 mg kg(-1) dw in shortfin mako (Isurus oxyrinchus), scalloped hammerhead (Sphyrna lewini), white (Carcharodon carcharias) and ragged-tooth (Carcharias taurus) sharks. These sharks had higher THg levels than conspecifics sampled from coastal waters of the North Atlantic and North, mid-, and South Pacific, and although sampling year and shark size may play a confounding role, this result suggests the potential importance of elevated local emissions. Values of THg showed strong, species-specific correlations with length, and nearly half the remaining variation was explained by trophic position (using nitrogen stable isotopes, δ(15)N), whereas measures of foraging habitat (using carbon stable isotopes, δ(13)C) were not significant. Mercury concentrations were above the regulatory guidelines for fish health effects and safe human consumption for 88% and 70% of species, respectively, suggesting on-going cause for concern for shark health, and human consumers of shark meat.
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Affiliation(s)
- Melissa A McKinney
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4, Canada.
| | - Kylie Dean
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Nigel E Hussey
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Geremy Cliff
- KwaZulu-Natal Sharks Board, Umhlanga Rocks 4320, South Africa; Biomedical Resource Unit, University of KwaZulu-Natal, Durban 4000, South Africa
| | - Sabine P Wintner
- KwaZulu-Natal Sharks Board, Umhlanga Rocks 4320, South Africa; Biomedical Resource Unit, University of KwaZulu-Natal, Durban 4000, South Africa
| | - Sheldon F J Dudley
- KwaZulu-Natal Sharks Board, Umhlanga Rocks 4320, South Africa; Department of Agriculture, Forestry and Fisheries, Cape Town 8012, South Africa
| | - M Philip Zungu
- Department of Agriculture, Forestry and Fisheries, Cape Town 8012, South Africa
| | - Aaron T Fisk
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4, Canada
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Davidson BC, Nel W, Rais A, Namdarizandi V, Vizarra S, Cliff G. Comparison of total lipids and fatty acids from liver, heart and abdominal muscle of scalloped (Sphyrna lewini) and smooth (Sphyrna zygaena) hammerhead sharks. SPRINGERPLUS 2014; 3:521. [PMID: 25279312 PMCID: PMC4167885 DOI: 10.1186/2193-1801-3-521] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 09/01/2014] [Indexed: 11/22/2022]
Abstract
Liver, heart and abdominal muscle samples from scalloped (Sphyrna lewini) and smooth (Sphyrna zygaena) hammerhead sharks were analysed to characterise their lipid and fatty acid profiles. Samples were compared both between and within species, but there were no significant differences in total lipids for either comparison, although much greater total amounts were found in the liver samples. Within the individual fatty acids, the only significant differences were greater amounts of 22:6n-3, total n-3 polyunsaturates and total polyunsaturates in smooth, when compared to scalloped, hammerhead liver. This may reflect the more wide spread distribution of this species into cooler waters. Within both species the liver levels of the same fatty acid fractions decreased from spring to summer, which may correlate with changes in fatty acid profile to adapt to any differences in amount or species of prey consumed, or other considerations, eg. buoyancy, however there was no data to clarify this.
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Affiliation(s)
- Bruce Clement Davidson
- Saint James School of Medicine, PO Box 318, Albert Lake Drive, The Quarter, Anguilla, AI-2640 British West Indies
| | - Wynand Nel
- Saint James School of Medicine, PO Box 318, Albert Lake Drive, The Quarter, Anguilla, AI-2640 British West Indies
| | - Afsha Rais
- Saint James School of Medicine, PO Box 318, Albert Lake Drive, The Quarter, Anguilla, AI-2640 British West Indies
| | - Vahid Namdarizandi
- Saint James School of Medicine, PO Box 318, Albert Lake Drive, The Quarter, Anguilla, AI-2640 British West Indies
| | - Scott Vizarra
- Saint James School of Medicine, PO Box 318, Albert Lake Drive, The Quarter, Anguilla, AI-2640 British West Indies
| | - Geremy Cliff
- KwaZulu-Natal Sharks Board, and Biomedical Resource Unit, University of KwaZulu-Natal, Private Bag 2, Umhlanga Rocks, 4320, Durban, 4056 KwaZulu-Natal South Africa
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Pethybridge HR, Parrish CC, Bruce BD, Young JW, Nichols PD. Lipid, fatty acid and energy density profiles of white sharks: insights into the feeding ecology and ecophysiology of a complex top predator. PLoS One 2014; 9:e97877. [PMID: 24871223 PMCID: PMC4037211 DOI: 10.1371/journal.pone.0097877] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Accepted: 04/25/2014] [Indexed: 01/28/2023] Open
Abstract
Lipids are major sources of metabolic energy in sharks and are closely linked to environmental conditions and biological cycles, such as those related to diet, reproduction and migration. In this study, we report for the first time, the total lipid content, lipid class composition and fatty acid profiles of muscle and liver tissue of white sharks, Carcharodon carcharias, of various lengths (1.5-3.9 m), sampled at two geographically separate areas off southern and eastern Australia. Muscle tissue was low in total lipid content (<0.9% wet mass, wm) and was dominated by phospholipids (>90% of total lipid) and polyunsaturated fatty acids (34±12% of total fatty acids). In contrast, liver was high in total lipid which varied between 51-81% wm and was dominated by triacylglycerols (>93%) and monounsaturated fatty acids (36±12%). With knowledge of total lipid and dry tissue mass, we estimated the energy density of muscle (18.4±0.1 kJ g-1 dm) and liver (34.1±3.2 kJ g-1 dm), demonstrating that white sharks have very high energetic requirements. High among-individual variation in these biochemical parameters and related trophic markers were observed, but were not related to any one biological or environmental factor. Signature fatty acid profiles suggest that white sharks over the size range examined are generalist predators with fish, elasmobranchs and mammalian blubber all contributing to the diet. The ecological applications and physiological influences of lipids in white sharks are discussed along with recommendations for future research, including the use of non-lethal sampling to examine the nutritional condition, energetics and dietary relationships among and between individuals. Such knowledge is fundamental to better understand the implications of environmental perturbations on this iconic and threatened species.
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Affiliation(s)
- Heidi R. Pethybridge
- CSIRO Wealth from Ocean Flagship, Division of Marine and Atmospheric Research, Hobart, Australia
| | - Christopher C. Parrish
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | - Barry D. Bruce
- CSIRO Wealth from Ocean Flagship, Division of Marine and Atmospheric Research, Hobart, Australia
| | - Jock W. Young
- CSIRO Wealth from Ocean Flagship, Division of Marine and Atmospheric Research, Hobart, Australia
| | - Peter D. Nichols
- CSIRO Wealth from Ocean Flagship, Division of Marine and Atmospheric Research, Hobart, Australia
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