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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/211360
The potential of carboxylesterase activity in the biomonitoring of marine pollution
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[eng] Understanding and monitoring the impacts of pollution on marine ecosystems leads the list of challenges of the United Nations Ocean Decade as crucial steps towards achieving a healthy ocean. The marine environment faces a constant influx of chemical pollutants from land, marine and atmospheric sources, resulting in complex pollutant mixtures that can cause a cascade of responses on marine biota, from biochemical to physiological. Biochemical responses, in particular, can serve as early biomarkers of exposure, susceptibility, or effect. Among them, carboxylesterases (CEs) are enzymes that hydrolyze a variety of substrates, and offer a cost-effective tool for monitoring marine pollution, especially in scenarios involving chemical mixtures. However, the current efforts are limited to few sentinel species mostly found in coastal environments. This Ph.D. thesis aims to broaden the knowledge on the use of CEs as biomarkers as well as to identify alternative sentinel species across different trophic levels and ecological niches in the under-monitored pelagic realm. Biomarker activities, in vitro inhibition tests, biological parameters (e.g., body size, body mass, sex or reproductive season) and environmental factors (e.g., sea temperature, salinity or dissolved oxygen) were considered in combination to unravel the response of CEs to pollutants of environmental concern and their natural variability. Among sentinels, we propose copepods (Paracartia grani and Centropages typicus), small pelagic fish (Sardina pilchardus and Engraulis encrasicolus), large predatory fish (Euthynnus alletteratus, Sarda sarda, Auxis rochei and Thunnus alalunga) and an opportunistic seabird (Larus michahellis). CEs activities and their sensitivity to chemicals of concern and specific inhibitors were assessed, highlighting the inhibitory potential of tetrabromobisphenol A at high levels of the pelagic trophic net. Moreover, the influence of biological and environmental parameters on CEs activities were evaluated in small pelagic fish, large predatory fish and gulls, being age, sex and the reproductive status the main factors modulating CEs activities. Overall, the findings of this Ph.D. thesis contribute to demonstrate how biological and environmental factors affect some biomarkers and particularly CE activity, making them relevant variables to take into account when interpreting biomarker responses. Additionally, we characterized and evidenced the species-specific differences on basal CE activities. Together, our contribution is a step forward towards the establishment of CEs as biomarkers of pollution not only in the marine pelagic environments but also in urban areas with anchovy and yellow-legged gulls as respective sentinels.
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NOS FRANCISCO, David. The potential of carboxylesterase activity in the biomonitoring of marine pollution. [consulta: 3 de desembre de 2025]. [Disponible a: https://hdl.handle.net/2445/211360]