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Baseline description of inorganic contaminants in juvenile sharks off the Boa Vista island nursery area (Cabo Verde)
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Resumo(s)
Understanding the health of local shark populations is crucial to assessing the impacts of human
activity on marine ecosystems and promoting the sustainable use of their resources. This study
establishes the first baseline data on the levels of inorganic contaminants (Al, Zn, As, Cu, Cr, Cd, Co,
Mn, Ti, Ni, Hg, and Pb) in juvenile sharks from the nursery area of Sal Rei (Boa Vista island, Cabo
Verde), focusing on four species: milk shark (Rhizoprionodon acutus), scalloped hammerhead shark
(Sphyrna lewini), blacktip shark (Carcharhinus limbatus), and Atlantic weasel shark (Paragaleus
pectoralis). Plasma samples from these sharks, along with sediment and sea water samples, were
collected from the study area. Subsequently, the elemental concentrations of all samples were
determined using total reflection X-ray fluorescence spectroscopy (TXRF S2 PICOFOX, Brucker,
Germany). For a better characterization of the sediments, we also performed their granulometric
description and applied pollution indices: Enrichment Factor (EF), Risk Index (RI), and Metal Pollution
Index (MPI). Only the MPI was performed to the sea water samples.
The elemental analyses of the abiotic factors revealed a generally low contaminated
environment. However, a slight anthropogenic elemental increase was detected through the pollution
indices in specific sampling locations, particularly in sites 1 and 2. These sites are near the fishing port
of Sal Rei, and additional contamination is likely due to the fishing activities of local residents.
As expected, the sharks exhibited low levels of inorganic contaminants, consistent with the
relatively undisturbed environment. However, interspecific differences were observed, with blacktip
sharks showing higher concentrations of copper (Cu) and milk and Atlantic weasel sharks showing
significantly higher arsenic (As) levels compared to the other species. Principal Component Analysis
(PCA) revealed distinct elemental signatures between the species, particularly between blacktip sharks
and Atlantic weasel sharks, likely due to differences in their respective feeding ecologies.
Descrição
Tese de mestrado, Ecologia Marinha , 2024, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
tubarões contaminantes inorgânicos área de berçário poluição marinha Cabo Verde Teses de mestrado - 2024