Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 780, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2021.146548
Keywords
Galeocerdo cuvier; Urban ecology; Marine predator; Fatty acids; Corticosteroids; Thyroid hormones; Nutritional ecology; Market gravity
Categories
Funding
- Disney Conservation Fund
- International SeaKeepers Society
- Batchelor Foundation Inc.
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo-FAPESP [2014/16320-7, 2017/25273-0]
Ask authors/readers for more resources
This study compared metabolic hormones and plasma fatty acids in juvenile female tiger sharks sampled in two areas of the subtropical north Atlantic with different levels of coastal urbanization. The results showed higher corticosteroid levels in sharks sampled in the more urbanized area, but no differences in thyroid hormone concentrations. Additionally, sharks from the more urbanized area had higher percentages of omega-3 polyunsaturated fatty acids, while those from the less urbanized area had higher percentages of bacterial markers.
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.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available