Metabolic and nutritional condition of juvenile tiger sharks exposed to regional differences in coastal urbanization

Author(s)

Rangel, Bianca de Sousa ^[1] ; Moreira, Renata Guimaraes ^[1] ; Niella, Yuri Vieira ^[2] ; Sulikowski, James A. ^[3] ; Hammerschlag, Neil ^{[4, 5]}

Affiliation

^[1] Univ Sao Paulo, Lab Metab & Reprod Organismos Aquat, Dept Fisiol, Inst Biociencias, Rua Matao, Travessa 14-321, BR-05508090 Sao Paulo, SP - Brazil

^[2] Macquarie Univ, Dept Biol Sci, N Ryde, NSW 2113 - Australia

^[3] Arizona State Univ, Sch Math & Nat Sci, Glendale, AZ 85306 - USA

^[4] Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Miami, FL 33149 - USA

^[5] Univ Miami, Leonard & Jayne Abess Ctr Ecosyst Sci & Policy, Coral Gables, FL 33146 - USA

• Document type: Journal article
• Source: Science of The Total Environment; v. 780, AUG 1 2021.
• Web of Science Citations: 0

Abstract

How varying levels of human activity, such as proximity and size of the nearest market (i.e., market gravity), influence the nutritional ecology and physiological condition of highly migratory marine predators is poorly understood. In the present study, we used a non-lethal approach to compare the concentration of metabolic hormones (i.e. corticosteroids and thyroid hormones) and plasma fatty acids between juvenile female tiger sharks (Galeocerdo cuvier) sampled in two areas of the subtropical north Atlantic, which differed markedly in their levels of coastal urbanization, Florida and the Bahamas (high versus low, respectively). We hypothesized that juvenile female tiger sharks sampled in water surrounding high coastal urbanization (Florida), would exhibit evidence of lower prey quality and higher energetic demands as compared to individuals sampled in relatively less urbanized areas of Northern Bahamas. Results revealed that relative corticosteroid levels (a proxy for energy mobilization) were higher in juvenile female tiger sharks sampled in Florida; however, no differences were found in concentrations of thyroid hormones (proxies of energetic adjustments) between the two locations. We found higher percentages of omega-3 polyunsaturated fatty acids (indicative of high prey quality) in juvenile tiger sharks from Florida, whereas higher percentages of bacterial markers (often indicative of domestic sewage effluent) were detected in the individuals sampled in the Bahamas. Taken together, these findings do not suggest that the differences in nutritional quality and metabolic condition found between the two sampling locations can be fully attributed to foraging in areas exposed to differing levels of urbanization. We speculate that these patterns may be due to the highly mi-gratory nature and generalist feeding strategy of this species, even at the juvenile life stage, as well as prox-imity of sampling locations from shore. (c) 2021 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 17/25273-0 - Ecophysiology and trophic relationships of elasmobranchs: biomarkers as tools for conservation
• Grantee: Bianca de Sousa Rangel
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 14/16320-7 - Impacts of climate/environmental change on the fauna: an integrative approach
• Grantee: Carlos Arturo Navas Iannini
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants