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Abstract
An annotated checklist of chondrichthyan fishes (sharks, batoids, and chimaeras) occurring in South African waters is presented. The checklist is the result of decades of research and on-going systematic revisions of the regional fauna. The chondrichthyan fauna of South Africa is one of the richest in the world with 191 species, comprising 50 families and 103 genera. It consists of 30 families, 64 genera, and 111 species of sharks; 17 families, 36 genera, and 72 species of batoids; and, 3 families, 5 genera, and 8 species of chimaeras. The most species-rich shark families are the whaler sharks Carcharhinidae with 20 species followed by the deepwater catsharks Pentanchidae with 13 species. The most species-rich batoid families are the hardnose stakes Rajidae with at least 21 species followed by the stingrays Dasyatidae with 13 species. This monograph represents the first detailed annotated checklist of chondrichthyans from South Africa in over 30 years.
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Affiliation(s)
- David A Ebert
- Pacific Shark Research Center, Moss Landing Marine Laboratories, Moss Landing, USA South African Institute for Aquatic Biodiversity, Grahamstown, South Africa Department of Ichthyology, California Academy of Sciences, San Francisco, USA.
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Pahl KB, Yurkowski DJ, Wintner SP, Cliff G, Dicken ML, Hussey NE. Determining the appropriate pretreatment procedures and the utility of liver tissue for bulk stable isotope (δ 13 C and δ 15 N) studies in sharks. J Fish Biol 2021; 98:829-841. [PMID: 33251592 DOI: 10.1111/jfb.14635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 11/11/2020] [Accepted: 11/27/2020] [Indexed: 06/12/2023]
Abstract
Stable-isotope analysis (SIA) provides a valuable tool to address complex questions pertaining to elasmobranch ecology. Liver, a metabolically active, high turnover tissue (~166 days for 95% turnover), has the potential to reveal novel insights into recent feeding/movement behaviours of this diverse group. To date, limited work has used this tissue, but ecological application of SIA in liver requires consideration of tissue preparation techniques given the potential for high concentrations of urea and lipid that could bias δ13 C and δ15 N values (i.e., result in artificially lower δ13 C and δ15 N values). Here we investigated the effectiveness of (a) deionized water washing (WW) for urea removal from liver tissue and (b) chloroform-methanol for extraction of lipids from this lipid rich tissue. We then (a) established C:N thresholds for deriving ecologically relevant liver isotopic values given complications of removing all lipid and (b) undertook a preliminary comparison of δ13 C values between tissue pairs (muscle and liver) to test if observed isotopic differences correlated with known movement behaviour. Tests were conducted on four large shark species: the dusky (DUS, Carcharhinus obscurus), sand tiger (RAG, Carcharias taurus), scalloped hammerhead (SCA, Sphyrna lewini) and white shark (GRE, Carcharodon carcharias). There was no significant difference in δ15 N values between lipid-extracted (LE) liver and lipid-extracted/water washed (WW) treatments, however, WW resulted in significant increases in %N, δ13 C and %C. Following lipid extraction (repeated three times), some samples were still biased by lipids. Our species-specific "C:N thresholds" provide a method to derive ecologically viable isotope data given the complexities of this lipid rich tissue (C:N thresholds of 4.0, 3.6, 4.7 and 3.9 for DUS, RAG, SCA and GRE liverLEWW tissue, respectively). The preliminary comparison of C:N threshold corrected liver and muscle δ13 C values corresponded with movement/habitat behaviours for each shark; minor differences in δ13 C values were observed for known regional movements of DUS and RAG (δ13 CDiffs = 0.24 ± 0.99‰ and 0.57 ± 0.38‰, respectively), while SCA and GRE showed greater differences (1.24 ± 0.63‰ and 1.08 ± 0.71‰, respectively) correlated to large-scale movements between temperate/tropical and pelagic/coastal environments. These data provide an approach for the successful application of liver δ13 C and δ15 N values to examine elasmobranch ecology.
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Affiliation(s)
- K Blue Pahl
- Department of Integrative Biology, University of Windsor, Windsor, Ontario, Canada
| | - David J Yurkowski
- Fisheries and Oceans Canada, Freshwater Institute, Winnipeg, Manitoba, Canada
| | - Sabine P Wintner
- KwaZulu-Natal Sharks Board, Maritime Centre of Excellence, Umhlanga Rocks, Umhlanga, South Africa
- Biomedical Resource Unit, University of KwaZulu-Natal, Durban, South Africa
- College of Agriculture, Engineering and Science, School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Geremy Cliff
- KwaZulu-Natal Sharks Board, Maritime Centre of Excellence, Umhlanga Rocks, Umhlanga, South Africa
- Biomedical Resource Unit, University of KwaZulu-Natal, Durban, South Africa
- College of Agriculture, Engineering and Science, School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Matthew L Dicken
- KwaZulu-Natal Sharks Board, Maritime Centre of Excellence, Umhlanga Rocks, Umhlanga, South Africa
- Department of Development Studies, School of Economics, Development and Tourism, Nelson Mandela University, Port Elizabeth, South Africa
- College of Agriculture, Engineering and Science, School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Nigel E Hussey
- Department of Integrative Biology, University of Windsor, Windsor, Ontario, Canada
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Maduna SN, Hull KL, Farrell ED, Boomer JJ, Veríssimo A, Marino IAM, Mazzoldi C, Zane L, Wintner SP, Chesalin MV, da Silva C, Gubili C, Mariani S, Bester-Van Der Merwe AE. Historical biogeography of smoothhound sharks (genus Mustelus) of Southern Africa reveals multiple dispersal events from the Northern Hemisphere. SYST BIODIVERS 2020. [DOI: 10.1080/14772000.2020.1787550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Simo N. Maduna
- Molecular Breeding and Biodiversity Group, Department of Genetics, Stellenbosch University, Private Bag XI, Stellenbosch, 7602, South Africa
- Division of Environment and Natural Resources, Norwegian Institute of Bioeconomy Research (NIBIO), N-1431 Ås, Norway
| | - Kelvin L. Hull
- Molecular Breeding and Biodiversity Group, Department of Genetics, Stellenbosch University, Private Bag XI, Stellenbosch, 7602, South Africa
| | - Edward D. Farrell
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Jessica J. Boomer
- Department of Biological Sciences, Macquarie University, 2109 Sydney, NSW, Australia
| | - Ana Veríssimo
- Research Centre in Biodiversity and Genetic Resources, Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão 4485-661, Portugal
- College of William and Mary, Virginia Institute of Marine Science, Route 1208, Greate Road, Gloucester Point, VA 23062, USA
| | - Ilaria A. M. Marino
- Department of Biology, University of Padova, Via U. Bassi 58/B 35131, Padova, Italy
- Consorzio Nazionale Interuniversitario per le Scienze del Mare (CoNISMa), Roma 00196, Italy
| | - Carlotta Mazzoldi
- Department of Biology, University of Padova, Via U. Bassi 58/B 35131, Padova, Italy
- Consorzio Nazionale Interuniversitario per le Scienze del Mare (CoNISMa), Roma 00196, Italy
| | - Lorenzo Zane
- Department of Biology, University of Padova, Via U. Bassi 58/B 35131, Padova, Italy
- Consorzio Nazionale Interuniversitario per le Scienze del Mare (CoNISMa), Roma 00196, Italy
| | - Sabine P. Wintner
- KwaZulu-Natal Sharks Board, Private Bag 2, Umhlanga Rocks, KwaZulu-Natal 4320, South Africa
- School of Life Sciences, University of KwaZulu-Natal, Durban 4000, South Africa
| | - Mikhail V. Chesalin
- A.O. Kovalevsky Institute of Biology of the Southern Seas of RAS, Russian Federation
| | - Charlene da Silva
- Department of Agriculture, Forestry and Fisheries: Branch: Fisheries Research Development, Inshore Research, Private Bag X2, Rogge Bay 8012, South Africa
| | - Chrysoula Gubili
- Fisheries Research Institute, Hellenic Agricultural Organization – DEMETER, Nea Peramos, 64007, Kavala, Greece
| | - Stefano Mariani
- School of Biological & Environmental Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - Aletta E. Bester-Van Der Merwe
- Molecular Breeding and Biodiversity Group, Department of Genetics, Stellenbosch University, Private Bag XI, Stellenbosch, 7602, South Africa
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Petta JC, Shipley ON, Wintner SP, Cliff G, Dicken ML, Hussey NE. Are you really what you eat? Stomach content analysis and stable isotope ratios do not uniformly estimate dietary niche characteristics in three marine predators. Oecologia 2020; 192:1111-1126. [DOI: 10.1007/s00442-020-04628-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Accepted: 02/27/2020] [Indexed: 10/24/2022]
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Lieber L, Hall G, Hall J, Berrow S, Johnston E, Gubili C, Sarginson J, Francis M, Duffy C, Wintner SP, Doherty PD, Godley BJ, Hawkes LA, Witt MJ, Henderson SM, de Sabata E, Shivji MS, Dawson DA, Sims DW, Jones CS, Noble LR. Spatio-temporal genetic tagging of a cosmopolitan planktivorous shark provides insight to gene flow, temporal variation and site-specific re-encounters. Sci Rep 2020; 10:1661. [PMID: 32015388 PMCID: PMC6997447 DOI: 10.1038/s41598-020-58086-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 12/29/2019] [Indexed: 12/30/2022] Open
Abstract
Migratory movements in response to seasonal resources often influence population structure and dynamics. Yet in mobile marine predators, population genetic consequences of such repetitious behaviour remain inaccessible without comprehensive sampling strategies. Temporal genetic sampling of seasonally recurring aggregations of planktivorous basking sharks, Cetorhinus maximus, in the Northeast Atlantic (NEA) affords an opportunity to resolve individual re-encounters at key sites with population connectivity and patterns of relatedness. Genetic tagging (19 microsatellites) revealed 18% of re-sampled individuals in the NEA demonstrated inter/multi-annual site-specific re-encounters. High genetic connectivity and migration between aggregation sites indicate the Irish Sea as an important movement corridor, with a contemporary effective population estimate (Ne) of 382 (CI = 241-830). We contrast the prevailing view of high gene flow across oceanic regions with evidence of population structure within the NEA, with early-season sharks off southwest Ireland possibly representing genetically distinct migrants. Finally, we found basking sharks surfacing together in the NEA are on average more related than expected by chance, suggesting a genetic consequence of, or a potential mechanism maintaining, site-specific re-encounters. Long-term temporal genetic monitoring is paramount in determining future viability of cosmopolitan marine species, identifying genetic units for conservation management, and for understanding aggregation structure and dynamics.
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Affiliation(s)
- Lilian Lieber
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, Scotland, UK
- School of Chemistry and Chemical Engineering, Queen´s University Belfast, Marine Laboratory, Portaferry, BT22 1PF, Northern Ireland, UK
| | - Graham Hall
- Manx Basking Shark Watch and Manx Wildlife Trust, Peel, Isle of Man, IM9 5PJ, UK
| | - Jackie Hall
- Manx Basking Shark Watch and Manx Wildlife Trust, Peel, Isle of Man, IM9 5PJ, UK
| | - Simon Berrow
- Irish Basking Shark Study Group, Merchants Quay, Kilrush, County Clare, UK
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Dublin Road, Galway, Ireland
| | - Emmett Johnston
- Irish Basking Shark Study Group, Merchants Quay, Kilrush, County Clare, UK
- School of Biological Sciences, Queen´s University Belfast, Belfast, Northern Ireland, UK
| | - Chrysoula Gubili
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, Scotland, UK
- Hellenic Agricultural Organisation, Fisheries Research Institute, Nea Peramos, Kavala, Macedonia, 64007, Greece
| | - Jane Sarginson
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, Scotland, UK
- Faculty of Science and Engineering, John Dalton Building, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK
| | - Malcolm Francis
- National Institute of Water and Atmospheric Research, Private Bag 14901, Kilbirnie, Wellington, 6241, New Zealand
| | - Clinton Duffy
- Department of Conservation, Private Bag 68908, Wellesley Street, Auckland, 1141, New Zealand
| | - Sabine P Wintner
- KwaZulu-Natal Sharks Board, Private Bag 2, Umhlanga Rocks, 4320, South Africa
- School of Life Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa
| | - Philip D Doherty
- Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn, TR10 9FE, UK
- Environment and Sustainability Institute, University of Exeter, Cornwall Campus, Penryn, TR10 9FE, UK
| | - Brendan J Godley
- Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn, TR10 9FE, UK
- Environment and Sustainability Institute, University of Exeter, Cornwall Campus, Penryn, TR10 9FE, UK
| | - Lucy A Hawkes
- Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn, TR10 9FE, UK
| | - Matthew J Witt
- Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn, TR10 9FE, UK
- Environment and Sustainability Institute, University of Exeter, Cornwall Campus, Penryn, TR10 9FE, UK
| | - Suzanne M Henderson
- Scottish Natural Heritage Great Glen House, Inverness, IV3 8NW, Scotland, UK
| | | | - Mahmood S Shivji
- Save Our Seas Shark Research Center and Guy Harvey Research Institute, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL, 33004, USA
| | - Deborah A Dawson
- NERC Biomolecular Analysis Facility, Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, South Yorkshire, UK
| | - David W Sims
- Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, Southampton, SO14 3ZH, UK
| | - Catherine S Jones
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, Scotland, UK
| | - Leslie R Noble
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, Scotland, UK.
- Faculty of Biosciences and Aquaculture, Nord University, Postboks 1490, 8049, Bodø, Norway.
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Corrigan S, Lowther AD, Beheregaray LB, Bruce BD, Cliff G, Duffy CA, Foulis A, Francis MP, Goldsworthy SD, Hyde JR, Jabado RW, Kacev D, Marshall L, Mucientes GR, Naylor GJP, Pepperell JG, Queiroz N, White WT, Wintner SP, Rogers PJ. Population Connectivity of the Highly Migratory Shortfin Mako (Isurus oxyrinchus Rafinesque 1810) and Implications for Management in the Southern Hemisphere. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00187] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Maduna SN, Rossouw C, Slabbert R, Wintner SP, da Silva C, Bester-van der Merwe AE. New polymorphic microsatellite loci revealed for the dusky shark Carcharhinus obscurus through Ion Proton double-digest RAD sequencing. Mol Biol Rep 2018; 45:2759-2763. [PMID: 30218351 DOI: 10.1007/s11033-018-4338-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 08/28/2018] [Indexed: 11/24/2022]
Abstract
The non-model shark species, dusky shark Carcharhinus obscurus, is a bio-economically and recreationally important shark in many areas of its range. Despite of the fishery importance of C. obscurus few genetic resources are currently available for the species. Here, we report on the isolation of eight novel microsatellite loci from C. obscurus using a double-digest restriction site associated DNA (RAD) sequencing approach on the Ion Proton semiconductor platform (ddRADseq-ion). We characterised the loci in 26 individuals and all loci were polymorphic, exhibiting 5-10 alleles (average 6.6), and observed and expected heterozygosities of 0.385-0.962 and 0.479-0.847, respectively. We found that all pairs of loci were in linkage equilibrium and conformed to Hardy-Weinberg expectations. The loci reported in this study are only the second set of microsatellite loci ever characterized for C. obscurus and will be valuable for molecular ecology studies for this vulnerable species.
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Affiliation(s)
- Simo N Maduna
- Molecular Breeding and Biodiversity Group, Department of Genetics, Stellenbosch University, Private Bag XI, Stellenbosch, 7602, South Africa.
- Norwegian Institute of Bioeconomy Research, NIBIO - Svanhovd, Svanvik, Norway.
| | - Charné Rossouw
- Molecular Breeding and Biodiversity Group, Department of Genetics, Stellenbosch University, Private Bag XI, Stellenbosch, 7602, South Africa
| | - Ruhan Slabbert
- Roche Sequencing Solutions Cape Town, 271 Victoria Road, Salt River, Cape Town, 7925, South Africa
| | - Sabine P Wintner
- KwaZulu-Natal Sharks Board, Private Bag 2, Umhlanga Rocks, 4320, South Africa
- School of Life Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa
| | - Charlene da Silva
- Fisheries Research, Department of Agriculture, Forestry and Fisheries, Private Bag X2, Rogge Bay, 8012, South Africa
- Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
| | - Aletta E Bester-van der Merwe
- Molecular Breeding and Biodiversity Group, Department of Genetics, Stellenbosch University, Private Bag XI, Stellenbosch, 7602, South Africa
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French GCA, Stürup M, Rizzuto S, van Wyk JH, Edwards D, Dolan RW, Wintner SP, Towner AV, Hughes WOH. The tooth, the whole tooth and nothing but the tooth: tooth shape and ontogenetic shift dynamics in the white shark Carcharodon carcharias. J Fish Biol 2017; 91:1032-1047. [PMID: 28815588 DOI: 10.1111/jfb.13396] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 07/18/2017] [Indexed: 06/07/2023]
Abstract
Results from this study of the white shark Carcharodon carcharias include measurements obtained using a novel photographic method that reveal significant differences between the sexes in the relationship between tooth cuspidity and shark total length, and a novel ontogenetic change in male tooth shape. Males exhibit broader upper first teeth and increased distal inclination of upper third teeth with increasing length, while females do not present a consistent morphological change. Substantial individual variation, with implications for pace of life syndrome, was present in males and tooth polymorphism was suggested in females. Sexual differences and individual variation may play major roles in ontogenetic changes in tooth morphology in C. carcharias, with potential implications for their foraging biology. Such individual and sexual differences should be included in studies of ontogenetic shift dynamics in other species and systems.
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Affiliation(s)
- G C A French
- School of Life Sciences, University of Sussex, Brighton, BN1 9QG, U.K
| | - M Stürup
- School of Life Sciences, University of Sussex, Brighton, BN1 9QG, U.K
| | - S Rizzuto
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch, 7600, South Africa
| | - J H van Wyk
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch, 7600, South Africa
| | - D Edwards
- Dyer Island Conservation Trust, Kleinbaai, South Africa
| | - R W Dolan
- Dyer Island Conservation Trust, Kleinbaai, South Africa
| | - S P Wintner
- KwaZulu-Natal Sharks Board and Biomedical Resource Unit, University of KwaZulu-Natal, Durban, 4000, South Africa
| | - A V Towner
- Dyer Island Conservation Trust, Kleinbaai, South Africa
| | - W O H Hughes
- School of Life Sciences, University of Sussex, Brighton, BN1 9QG, U.K
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Dicken ML, Hussey NE, Christiansen HM, Smale MJ, Nkabi N, Cliff G, Wintner SP. Diet and trophic ecology of the tiger shark (Galeocerdo cuvier) from South African waters. PLoS One 2017; 12:e0177897. [PMID: 28594833 PMCID: PMC5464543 DOI: 10.1371/journal.pone.0177897] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 05/04/2017] [Indexed: 11/18/2022] Open
Abstract
Knowledge of the diet and trophic ecology of apex predators is key for the implementation of effective ecosystem as well as species-based management initiatives. Using a combination of stomach content data and stable isotope analysis (δ15N and δ13C) the current study provides information on size-based and sex-specific variations in diet, trophic position (TP) and foraging habitat of tiger sharks (Galeocerdo cuvier) caught in the KwaZulu-Natal Sharks Board bather protection program. This study presents the longest time-series and most detailed analysis of stomach content data for G. cuvier worldwide. Prey identified from 628 non-empty stomachs revealed a size-based shift in diet. Reptiles, birds, mysticetes, and large shark species increased in dietary importance with G. cuvier size, concomitant with a decrease in smaller prey such as batoids and teleosts. Seasonal and decadal shifts in diet driven primarily by changes in the importance of elasmobranchs and mammal (cetacean) prey were recorded for medium sized (150-220 cm) G. cuvier. Both stomach content and stable isotope analysis indicated that G. cuvier is a generalist feeder at the population level. Size-based δ13C profiles indicated a movement to offshore foraging habitats by larger G. cuvier. Calculated TP varied by method ranging from 4.0 to 5.0 (TPSCA for stomach contents) and from 3.6 to 4.5 (TPscaled and TPadditive for δ15N). Large (> 220 cm) G. cuvier did not feed at discrete trophic levels, but rather throughout the food web. These data provide key information on the ecological role of G. cuvier to improve the accuracy of regional food web modelling. This will enable a better understanding of the ecological impacts related to changes in the abundance of this predator.
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Affiliation(s)
- Matthew L. Dicken
- KwaZulu-Natal Sharks Board, Umhlanga Rocks, South Africa
- Department of Zoology and Entomology, University of Fort Hare, Alice. South Africa
- * E-mail:
| | - Nigel E. Hussey
- University of Windsor–Biological Sciences, Windsor, Ontario, Canada
| | | | - Malcolm J. Smale
- Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa
- Port Elizabeth Museum, Humewood, Port Elizabeth, South Africa
| | - Nomfundo Nkabi
- KwaZulu-Natal Sharks Board, Umhlanga Rocks, South Africa
| | - Geremy Cliff
- KwaZulu-Natal Sharks Board, Umhlanga Rocks, South Africa
- Biomedical Resource Unit, University of KwaZulu-Natal, Durban South Africa
| | - Sabine P. Wintner
- KwaZulu-Natal Sharks Board, Umhlanga Rocks, South Africa
- Biomedical Resource Unit, University of KwaZulu-Natal, Durban South Africa
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Bernard AM, Feldheim KA, Heithaus MR, Wintner SP, Wetherbee BM, Shivji MS. Global population genetic dynamics of a highly migratory, apex predator shark. Mol Ecol 2016; 25:5312-5329. [DOI: 10.1111/mec.13845] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 08/09/2016] [Accepted: 08/25/2016] [Indexed: 01/19/2023]
Affiliation(s)
- Andrea M. Bernard
- Save Our Seas Shark Research Center Halmos College of Natural Sciences & Oceanography Nova Southeastern University 8000 N. Ocean Drive Dania Beach FL 33004 USA
| | - Kevin A. Feldheim
- The Field Museum of Natural History Pritzker Laboratory for Molecular Systematics and Evolution 1400 South Lake Shore Drive Chicago IL 60605 USA
| | - Michael R. Heithaus
- School of Environment and Society Florida International University Miami FL USA
| | - Sabine P. Wintner
- KwaZulu‐Natal Sharks Board Private Bag 2 Umhlanga Rocks 4320 South Africa
- Biomedical Resource Unit University of KwaZulu‐Natal Durban 4000 South Africa
| | - Bradley M. Wetherbee
- Department of Biological Sciences University of Rhode Island Kingston RI USA
- Guy Harvey Research Institute Dania Beach, FL 33004 USA
| | - Mahmood S. Shivji
- Save Our Seas Shark Research Center and Guy Harvey Research Institute Halmos College of Natural Sciences & Oceanography Nova Southeastern University 8000 N. Ocean Drive Dania Beach FL 33004 USA
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Rossouw C, Wintner SP, Bester-Van Der Merwe AE. Assessing multiple paternity in three commercially exploited shark species: Mustelus mustelus, Carcharhinus obscurus and Sphyrna lewini. J Fish Biol 2016; 89:1125-41. [PMID: 27237109 DOI: 10.1111/jfb.12996] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 04/06/2016] [Indexed: 05/15/2023]
Abstract
In this study, multiple paternity (MP) was investigated in three commercially important shark species, common smoothhound Mustelus mustelus, dusky shark Carcharhinus obscurus and scalloped hammerhead Sphyrna lewini occurring in southern Africa. Reduced marker panels of between five and six microsatellite loci were constructed for each species and used to genotype and assess the presence of MP in a total of 60 M. mustelus individuals from six litters, 90 C. obscurus individuals from 14 litters and 54 S. lewini individuals from 13 litters. Analysis in GERUD and COLONY revealed the presence of MP in all three species. Multiple paternities were observed in 67, 35 and 46% of the litters of M. mustelus, C. obscurus and S. lewini, with corresponding average sire size of 1·6, 1·4 and 2·0, respectively. The variation in the rate of MP among the three species is in accordance with previous studies whilst the comparatively high frequency of MP observed for M. mustelus, matches what has previously been reported for shark species demonstrating aggregation behaviour.
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Affiliation(s)
- C Rossouw
- Department of Genetics, Stellenbosch University, Private Bag 1X, Matieland, 7602, South Africa
| | - S P Wintner
- KwaZulu-Natal Sharks Board and Biomedical Resource Unit, University of KwaZulu-Natal, Durban, 4000, 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. Sci Total Environ 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Beaudry MC, Hussey NE, McMeans BC, McLeod AM, Wintner SP, Cliff G, Dudley SFJ, Fisk AT. Comparative organochlorine accumulation in two ecologically similar shark species (Carcharodon carcharias and Carcharhinus obscurus) with divergent uptake based on different life history. Environ Toxicol Chem 2015; 34:2051-2060. [PMID: 25899033 DOI: 10.1002/etc.3029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 12/10/2014] [Accepted: 04/15/2015] [Indexed: 06/04/2023]
Abstract
Trophic position and body mass are traits commonly used to predict organochlorine burdens. Sharks, however, have a variety of feeding and life history strategies and metabolize lipid uniquely. Because of this diversity, and the lipid-association of organochlorines, the dynamics of organochlorine accumulation in sharks may be predicted ineffectively by stable isotope-derived trophic position and body mass, as is typical for other taxa. The present study compared ontogenetic organochlorine profiles in the dusky shark (Carcharhinus obscurus) and white shark (Carcharodon carcharias), which differ in metabolic thermoregulation and trophic position throughout their ontogeny. Although greater organochlorine concentrations were observed in the larger bodied and higher trophic position white shark (e.g., p,p'-dichlorodiphenyldichloroethylene: 20.2 ± 2.7 ng/g vs 9.3 ± 2.2 ng/g in the dusky shark), slopes of growth-dilution corrected concentrations with age were equal to those of the dusky shark. Similar ontogenetic trophic position increases in both species, less frequent white shark seal predation than previously assumed, or inaccurate species-specific growth parameters are possible explanations. Inshore habitat use (indicated by δ(13)C values) and mass were important predictors in white and dusky sharks, respectively, of both overall compound profiles and select organochlorine concentrations. The present study clarified understanding of trophic position and body mass as reliable predictors of interspecific organochlorine accumulation in sharks, whereas regional endothermy and diet shifting were shown to have less impact on overall rates of accumulation.
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Affiliation(s)
- Marina C Beaudry
- Great Lakes Institute for Environmental Research, University of Windsor, Ontario, Canada
| | - Nigel E Hussey
- Great Lakes Institute for Environmental Research, University of Windsor, Ontario, Canada
| | - Bailey C McMeans
- Department of Integrative Biology, University of Guelph, Ontario, Canada
| | - Anne M McLeod
- Great Lakes Institute for Environmental Research, University of Windsor, Ontario, Canada
| | - Sabine P Wintner
- KwaZulu-Natal Sharks Board, Umhlanga, KwaZulu-Natal, South Africa
- Biomedical Resource Unit, University of KwaZulu-Natal, KwaZulu-Natal, South Africa
| | - Geremy Cliff
- KwaZulu-Natal Sharks Board, Umhlanga, KwaZulu-Natal, South Africa
- Biomedical Resource Unit, University of KwaZulu-Natal, KwaZulu-Natal, South Africa
| | - Sheldon F J Dudley
- KwaZulu-Natal Sharks Board, Umhlanga, KwaZulu-Natal, South Africa
- Biomedical Resource Unit, University of KwaZulu-Natal, KwaZulu-Natal, South Africa
- Department of Agriculture, Forestry and Fisheries, Cape Town, South Africa
| | - Aaron T Fisk
- Great Lakes Institute for Environmental Research, University of Windsor, Ontario, Canada
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Gubili C, Robinson CEC, Cliff G, Wintner SP, de Sabata E, De Innocentiis S, Canese S, Sims DW, Martin AP, Noble LR, Jones CS. DNA from historical and trophy samples provides insights into white shark population origins and genetic diversity. ENDANGER SPECIES RES 2015. [DOI: 10.3354/esr00665] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Rohner CA, Richardson AJ, Prebble CEM, Marshall AD, Bennett MB, Weeks SJ, Cliff G, Wintner SP, Pierce SJ. Laser photogrammetry improves size and demographic estimates for whale sharks. PeerJ 2015; 3:e886. [PMID: 25870776 PMCID: PMC4393817 DOI: 10.7717/peerj.886] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 03/19/2015] [Indexed: 11/20/2022] Open
Abstract
Whale sharks Rhincodon typus are globally threatened, but a lack of biological and demographic information hampers an accurate assessment of their vulnerability to further decline or capacity to recover. We used laser photogrammetry at two aggregation sites to obtain more accurate size estimates of free-swimming whale sharks compared to visual estimates, allowing improved estimates of biological parameters. Individual whale sharks ranged from 432-917 cm total length (TL) (mean ± SD = 673 ± 118.8 cm, N = 122) in southern Mozambique and from 420-990 cm TL (mean ± SD = 641 ± 133 cm, N = 46) in Tanzania. By combining measurements of stranded individuals with photogrammetry measurements of free-swimming sharks, we calculated length at 50% maturity for males in Mozambique at 916 cm TL. Repeat measurements of individual whale sharks measured over periods from 347-1,068 days yielded implausible growth rates, suggesting that the growth increment over this period was not large enough to be detected using laser photogrammetry, and that the method is best applied to estimating growth rates over longer (decadal) time periods. The sex ratio of both populations was biased towards males (74% in Mozambique, 89% in Tanzania), the majority of which were immature (98% in Mozambique, 94% in Tanzania). The population structure for these two aggregations was similar to most other documented whale shark aggregations around the world. Information on small (<400 cm) whale sharks, mature individuals, and females in this region is lacking, but necessary to inform conservation initiatives for this globally threatened species.
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Affiliation(s)
- Christoph A Rohner
- Marine Megafauna Foundation , Praia do Tofo Inhambane , Mozambique ; CSIRO Oceans and Atmosphere Flagship , Brisbane Queensland , Australia
| | - Anthony J Richardson
- CSIRO Oceans and Atmosphere Flagship , Brisbane Queensland , Australia ; Centre for Applications in Natural Resource Mathematics (CARM), School of Mathematics and Physics, The University of Queensland , St Lucia Queensland , Australia
| | | | - Andrea D Marshall
- Marine Megafauna Foundation , Praia do Tofo Inhambane , Mozambique ; Wild Me , Praia do Tofo Inhambane , Mozambique
| | - Michael B Bennett
- School of Biomedical Sciences, The University of Queensland , St Lucia Queensland , Australia
| | - Scarla J Weeks
- Biophysical Oceanography Group, School of Geography, Planning and Environmental Management, The University of Queensland , St Lucia Queensland , Australia
| | - Geremy Cliff
- KwaZulu-Natal Sharks Board , Umhlanga , South Africa ; Biomedical Resource Unit, University of KwaZulu-Natal , Durban , South Africa
| | - Sabine P Wintner
- KwaZulu-Natal Sharks Board , Umhlanga , South Africa ; Biomedical Resource Unit, University of KwaZulu-Natal , Durban , South Africa
| | - Simon J Pierce
- Marine Megafauna Foundation , Praia do Tofo Inhambane , Mozambique ; Wild Me , Praia do Tofo Inhambane , Mozambique
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Affiliation(s)
- Nigel E. Hussey
- University of Windsor; Great Lakes Institute for Environmental Research
| | | | | | - Jill A. Olin
- Louisiana State University; School of the Coast & Environment
| | | | - Geremy Cliff
- KwaZulu-Natal Sharks Board
- Biomedical Resource Unit; University of KwaZulu-Natal
| | - Sabine P. Wintner
- KwaZulu-Natal Sharks Board
- Biomedical Resource Unit; University of KwaZulu-Natal
| | | | - Aaron T. Fisk
- University of Windsor; Great Lakes Institute for Environmental Research
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Christiansen HM, Lin V, Tanaka S, Velikanov A, Mollet HF, Wintner SP, Fordham SV, Fisk AT, Hussey NE. The last frontier: catch records of white sharks (Carcharodon carcharias) in the Northwest Pacific Ocean. PLoS One 2014; 9:e94407. [PMID: 24740299 PMCID: PMC3989224 DOI: 10.1371/journal.pone.0094407] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 03/11/2014] [Indexed: 11/18/2022] Open
Abstract
White sharks are highly migratory apex predators, globally distributed in temperate, sub-tropical, and tropical waters. Knowledge of white shark biology and ecology has increased recently based on research at known aggregation sites in the Indian, Atlantic, and Northeast Pacific Oceans; however, few data are available for the Northwest Pacific Ocean. This study provides a meta-analysis of 240 observations of white sharks from the Northwest Pacific Ocean between 1951 and 2012. Records comprise reports of bycatch in commercial fisheries, media accounts, personal communications, and documentation of shark-human interactions from Russia (n = 8), Republic of Korea (22), Japan (129), China (32), Taiwan (45), Philippines (1) and Vietnam (3). Observations occurred in all months, excluding October-January in the north (Russia and Republic of Korea) and July-August in the south (China, Taiwan, Philippines, and Vietnam). Population trend analysis indicated that the relative abundance of white sharks in the region has remained relatively stable, but parameterization of a 75% increase in observer effort found evidence of a minor decline since 2002. Reliably measured sharks ranged from 126–602 cm total length (TL) and 16–2530 kg total weight. The largest shark in this study (602 cm TL) represents the largest measured shark on record worldwide. For all countries combined the sex ratio was non-significantly biased towards females (1∶1.1; n = 113). Of 60 females examined, 11 were confirmed pregnant ranging from the beginning stages of pregnancy (egg cases) to near term (140 cm TL embryos). On average, 6.0±2.2 embryos were found per litter (maximum of 10) and gestation period was estimated to be 20 months. These observations confirm that white sharks are present in the Northwest Pacific Ocean year-round. While acknowledging the difficulties of studying little known populations of a naturally low abundance species, these results highlight the need for dedicated research to inform regional conservation and management planning.
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Affiliation(s)
- Heather M. Christiansen
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada
- * E-mail:
| | | | - Sho Tanaka
- School of Marine Science and Technology, Tokai University, Shimizu, Shizuoka, Japan
| | - Anatoly Velikanov
- Division of Marine and Freshwater Biological Resources, Sakhalin Research Institute of Fisheries & Oceanography, Yuzhno-Sakhalinsk, Russia
| | - Henry F. Mollet
- Moss Landing Marine Laboratories, Moss Landing, California, United States of America
- Monterey Bay Aquarium, Monterey, California, United States of America
| | - Sabine P. Wintner
- KwaZulu-Natal Sharks Board, Umhlanga Rocks, South Africa
- Biomedical Resource Unit, University of KwaZulu-Natal, Durban, South Africa
| | - Sonja V. Fordham
- Shark Advocates International (a project of The Ocean Foundation), Washington, DC, United States of America
| | - Aaron T. Fisk
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada
| | - Nigel E. Hussey
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada
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Christiansen HM, Hussey NE, Wintner SP, Cliff G, Dudley SFJ, Fisk AT. Effect of sample preparation techniques for carbon and nitrogen stable isotope analysis of hydroxyapatite structures in the form of elasmobranch vertebral centra. Rapid Commun Mass Spectrom 2014; 28:448-456. [PMID: 24497282 DOI: 10.1002/rcm.6801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 12/06/2013] [Accepted: 12/07/2013] [Indexed: 06/03/2023]
Abstract
RATIONALE Bulk stable isotope analysis (SIA) provides an important tool for the study of animal ecology. Elasmobranch vertebral centra can be serially sampled to obtain an isotopic history of an individual over ontogeny. The measured total δ(13)C value, however, may be misinterpreted due to the inclusion of the (13)C-rich inorganic portion. Hydrochloric acid (HCl) is commonly used to remove the inorganic portion of hydroxyapatite structures before undertaking SIA, but more recently ethylenediaminetetraacetic acid (EDTA) has been recommended for elasmobranch vertebrae. These acid treatments may introduce uncertainty on measured δ(13)C and δ(15)N values above instrument precision and the effect of small sample size remains untested for elasmobranch vertebrae. METHODS Using a non-dilution program on an isotope ratio mass spectrometer the minimum sample weight of vertebrae required to obtain accurate isotopic values was determined for three shark species: white (Carcharodon carcharias), tiger (Galeocerdo cuvier), and sand tiger (Carcharias taurus). To examine if acid treatment completely removes the inorganic component of the vertebrae or whether the technique introduces its own uncertainty on measured δ(13)C and δ(15)N values, vertebrae samples were analyzed untreated and following EDTA treatment. RESULTS The minimum sample weight required for accurate stable isotope values and the percentage sample yield following EDTA treatment varied within and among species. After EDTA treatment, white shark vertebrae were all enriched in (13)C and depleted in (15) N, tiger shark vertebrae showed both enrichment and depletion of (13)C and (15)N, and sand tiger shark vertebrae were all depleted in (13)C and (15)N. CONCLUSIONS EDTA treatment of elasmobranch vertebrae produces unpredictable effects (i.e. non-linear and non-correctable) among species in both the percentage sample yield and the measured δ(13)C and δ(15)N values. Prior to initiating a large-scale study, we strongly recommend investigating (i) the minimum weight of vertebral material required to obtain consistent isotopic values and (ii) the effects of EDTA treatment, specific to the study species and the isotope ratio mass spectrometer employed.
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Affiliation(s)
- Heather M Christiansen
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, N9B 3P4, Canada
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Hussey NE, MacNeil MA, McMeans BC, Olin JA, Dudley SFJ, Cliff G, Wintner SP, Fennessy ST, Fisk AT. Rescaling the trophic structure of marine food webs. Ecol Lett 2014; 17:239-50. [PMID: 24308860 PMCID: PMC3912912 DOI: 10.1111/ele.12226] [Citation(s) in RCA: 311] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 07/05/2013] [Accepted: 10/29/2013] [Indexed: 12/25/2022]
Abstract
Measures of trophic position (TP) are critical for understanding food web interactions and human-mediated ecosystem disturbance. Nitrogen stable isotopes (δ(15) N) provide a powerful tool to estimate TP but are limited by a pragmatic assumption that isotope discrimination is constant (change in δ(15) N between predator and prey, Δ(15) N = 3.4‰), resulting in an additive framework that omits known Δ(15) N variation. Through meta-analysis, we determine narrowing discrimination from an empirical linear relationship between experimental Δ(15) N and δ(15) N values of prey consumed. The resulting scaled Δ(15) N framework estimated reliable TPs of zooplanktivores to tertiary piscivores congruent with known feeding relationships that radically alters the conventional structure of marine food webs. Apex predator TP estimates were markedly higher than currently assumed by whole-ecosystem models, indicating perceived food webs have been truncated and species-interactions over simplified. The scaled Δ(15) N framework will greatly improve the accuracy of trophic estimates widely used in ecosystem-based management.
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Affiliation(s)
- Nigel E Hussey
- Great Lakes Institute for Environmental Research, University of Windsor401 Sunset Avenue, Windsor, ON N9B 3P4, Canada
| | - M Aaron MacNeil
- Australian Institute of Marine SciencePMB No.3, Townsville MC, Townsville, QLD 4810, Australia
| | - Bailey C McMeans
- Great Lakes Institute for Environmental Research, University of Windsor401 Sunset Avenue, Windsor, ON N9B 3P4, Canada
- Department of Integrative Biology, University of GuelphGuelph, ON N1G 2W1, Canada
| | - Jill A Olin
- Great Lakes Institute for Environmental Research, University of Windsor401 Sunset Avenue, Windsor, ON N9B 3P4, Canada
- Department of Oceanography and Coastal Sciences, Louisiana State UniversityBaton Rouge, LA, 70803, USA
| | - Sheldon FJ Dudley
- Department of Agriculture, Forest and FisheriesPrivate Bag X2, Rogge Bay 8012, Cape Town, South Africa
- KwaZulu-Natal Sharks BoardPrivate Bag 2, Umhlanga Rocks 4320, KwaZulu-Natal, South Africa
- Biomedical Resource Unit, University of KwaZulu-NatalPrivate Bag X54001, Durban 4056, South Africa
| | - Geremy Cliff
- KwaZulu-Natal Sharks BoardPrivate Bag 2, Umhlanga Rocks 4320, KwaZulu-Natal, South Africa
- Biomedical Resource Unit, University of KwaZulu-NatalPrivate Bag X54001, Durban 4056, South Africa
| | - Sabine P Wintner
- KwaZulu-Natal Sharks BoardPrivate Bag 2, Umhlanga Rocks 4320, KwaZulu-Natal, South Africa
- Biomedical Resource Unit, University of KwaZulu-NatalPrivate Bag X54001, Durban 4056, South Africa
| | - Sean T Fennessy
- Oceanographic Research InstitutePO Box 10712, Marine Parade, Durban 4056, South Africa
| | - Aaron T Fisk
- Great Lakes Institute for Environmental Research, University of Windsor401 Sunset Avenue, Windsor, ON N9B 3P4, Canada
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Olin JA, Hussey NE, Grgicak-Mannion A, Fritts MW, Wintner SP, Fisk AT. Variable δ(15)N diet-tissue discrimination factors among sharks: implications for trophic position, diet and food web models. PLoS One 2013; 8:e77567. [PMID: 24147026 PMCID: PMC3798323 DOI: 10.1371/journal.pone.0077567] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 09/03/2013] [Indexed: 11/20/2022] Open
Abstract
The application of stable isotopes to characterize the complexities of a species foraging behavior and trophic relationships is dependent on assumptions of δ15N diet-tissue discrimination factors (∆15N). As ∆15N values have been experimentally shown to vary amongst consumers, tissues and diet composition, resolving appropriate species-specific ∆15N values can be complex. Given the logistical and ethical challenges of controlled feeding experiments for determining ∆15N values for large and/or endangered species, our objective was to conduct an assessment of a range of reported ∆15N values that can hypothetically serve as surrogates for describing the predator-prey relationships of four shark species that feed on prey from different trophic levels (i.e., different mean δ15N dietary values). Overall, the most suitable species-specific ∆15N values decreased with increasing dietary-δ15N values based on stable isotope Bayesian ellipse overlap estimates of shark and the principal prey functional groups contributing to the diet determined from stomach content analyses. Thus, a single ∆15N value was not supported for this speciose group of marine predatory fishes. For example, the ∆15N value of 3.7‰ provided the highest percent overlap between prey and predator isotope ellipses for the bonnethead shark (mean diet δ15N = 9‰) whereas a ∆15N value < 2.3‰ provided the highest percent overlap between prey and predator isotope ellipses for the white shark (mean diet δ15N = 15‰). These data corroborate the previously reported inverse ∆15N-dietary δ15N relationship when both isotope ellipses of principal prey functional groups and the broader identified diet of each species were considered supporting the adoption of different ∆15N values that reflect the predators’ δ15N-dietary value. These findings are critical for refining the application of stable isotope modeling approaches as inferences regarding a species’ ecological role in their community will be influenced with consequences for conservation and management actions.
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Affiliation(s)
- Jill A Olin
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada
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Geraghty PT, Williamson JE, Macbeth WG, Wintner SP, Harry AV, Ovenden JR, Gillings MR. Population expansion and genetic structure in Carcharhinus brevipinna in the southern Indo-Pacific. PLoS One 2013; 8:e75169. [PMID: 24086462 PMCID: PMC3783459 DOI: 10.1371/journal.pone.0075169] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 08/12/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Quantifying genetic diversity and metapopulation structure provides insights into the evolutionary history of a species and helps develop appropriate management strategies. We provide the first assessment of genetic structure in spinner sharks (Carcharhinus brevipinna), a large cosmopolitan carcharhinid, sampled from eastern and northern Australia and South Africa. METHODS AND FINDINGS Sequencing of the mitochondrial DNA NADH dehydrogenase subunit 4 gene for 430 individuals revealed 37 haplotypes and moderately high haplotype diversity (h = 0.6770 ±0.025). While two metrics of genetic divergence (ΦST and F ST) revealed somewhat different results, subdivision was detected between South Africa and all Australian locations (pairwise ΦST, range 0.02717-0.03508, p values ≤ 0.0013; pairwise F ST South Africa vs New South Wales = 0.04056, p = 0.0008). Evidence for fine-scale genetic structuring was also detected along Australia's east coast (pairwise ΦST = 0.01328, p < 0.015), and between south-eastern and northern locations (pairwise ΦST = 0.00669, p < 0.04). CONCLUSIONS The Indian Ocean represents a robust barrier to contemporary gene flow in C. brevipinna between Australia and South Africa. Gene flow also appears restricted along a continuous continental margin in this species, with data tentatively suggesting the delineation of two management units within Australian waters. Further sampling, however, is required for a more robust evaluation of the latter finding. Evidence indicates that all sampled populations were shaped by a substantial demographic expansion event, with the resultant high genetic diversity being cause for optimism when considering conservation of this commercially-targeted species in the southern Indo-Pacific.
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Affiliation(s)
- Pascal T. Geraghty
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
- Cronulla Fisheries Research Centre of Excellence, New South Wales Department of Primary Industries, Sydney, New South Wales, Australia
| | - Jane E. Williamson
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - William G. Macbeth
- Cronulla Fisheries Research Centre of Excellence, New South Wales Department of Primary Industries, Sydney, New South Wales, Australia
| | - Sabine P. Wintner
- KwaZulu-Natal Sharks Board, Umhlanga Rocks, KwaZulu-Natal, South Africa
| | - Alastair V. Harry
- Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Queensland, Australia
| | - Jennifer R. Ovenden
- Molecular Fisheries Laboratory, the University of Queensland, St. Lucia, Queensland, Australia
| | - Michael R. Gillings
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
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Chapman DD, Wintner SP, Abercrombie DL, Ashe J, Bernard AM, Shivji MS, Feldheim KA. The behavioural and genetic mating system of the sand tiger shark, Carcharias taurus, an intrauterine cannibal. Biol Lett 2013; 9:20130003. [PMID: 23637391 DOI: 10.1098/rsbl.2013.0003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sand tiger sharks (Carcharias taurus) have an unusual mode of reproduction, whereby the first embryos in each of the paired uteri to reach a certain size ('hatchlings') consume all of their smaller siblings during gestation ('embryonic cannibalism' or EC). If females commonly mate with multiple males ('behavioural polyandry') then litters could initially have multiple sires. It is possible, however, that EC could exclude of all but one of these sires from producing offspring thus influencing the species genetic mating system ('genetic monogamy'). Here, we use microsatellite DNA profiling of mothers and their litters (n = 15, from two to nine embryos per litter) to quantify the frequency of behavioural and genetic polyandry in this system. We conservatively estimate that nine of the females we examined (60%) were behaviourally polyandrous. The genetic mating system was characterized by assessing sibling relationships between hatchlings and revealed only 40 per cent genetic polyandry (i.e. hatchlings were full siblings in 60% of litters). The discrepancy stemmed from three females that were initially fertilized by multiple males but only produced hatchlings with one of them. This reveals that males can be excluded even after fertilizing ova and that some instances of genetic monogamy in this population arise from the reduction in litter size by EC. More research is needed on how cryptic post-copulatory and post-zygotic processes contribute to determining paternity and bridging the behavioural and genetic mating systems of viviparous species.
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Affiliation(s)
- Demian D Chapman
- School of Marine and Atmospheric Science, Institute for Ocean Conservation Science, Stony Brook University, Stony Brook, NY 11794, USA.
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Hussey NE, Wintner SP, Dudley SFJ, Cliff G, Cocks DT, Aaron MacNeil M. Maternal investment and size-specific reproductive output in carcharhinid sharks. J Anim Ecol 2010; 79:184-93. [DOI: 10.1111/j.1365-2656.2009.01623.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hussey NE, Wintner SP, Dudley SFJ, Cliff G, Cocks DT. Questioning maternal resource allocation in sharks. Comp Biochem Physiol A Mol Integr Physiol 2009. [DOI: 10.1016/j.cbpa.2009.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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