Effects of the organic UV filters, oxybenxone and 4-methylbenzylidene champor, on the photobiology of the hexacoral Zoanthus sp.
Year: 2017
Type: dissertation
Abstract: Coral reefs are extremely complex and productive ecosystems, providing habitat for thousands of marine species. Despite their ecological and socio-economic importance, coral reefs are globally threatened by natural and anthropogenic impacts. The discharge of domestic and industrial wastes contributes for the introduction of xenobiotics, namely organic UV filters, in marine ecosystems such as coral reefs, contributing for their degradation over the past few decades. It is estimated that approximately 40 % of coral reefs located along coastal areas are at risk of exposure to organic UV filters such as Benzophenone-3 (BP-3) and 3-(4-methylbenzylidene) camphor (4-MBC), two widely used compounds in sunscreen lotions and personal-care products. It is therefore important to evaluate the effects of these emerging contaminants on local species inhabiting the more affected areas, namely the intertidal environments. The genus Zoanthus (Anthozoa: Hexacorallia) contains numerous species abundant in coral reefs and intertidal areas of tropical and sub-tropical regions. These photosynthetic corals, which live in symbiosis with dinoflagellates of genus Symbiodinium, might have potential application as indicator organisms. The existing research in zoanthids ecology is however scarce in comparison with other cnidarian groups. In this study, we aimed to evaluate the effects of short-term exposure of Zoanthus sp. to BP-3 and 4-MBC. Zoanthus sp. mini colonies (4 – 6 polyps) were exposed to 4 concentrations (0.5; 1, 2 and 4 mg/L) of BP-3 and 4-MBC during 96 h. After exposure, mini colonies were photographed for polyp behavioral response evaluation, the photosynthetic efficiency of photosystem II was measured in vivo, through PAM fluorometry, and finally, the Symbiodinium sp. cells were quantified and normalized to Zoanthus sp. dry weight. Results suggested that Zoanthus sp. exposure to sub-lethal and environmentally relevant concentrations of BP-3 and 4-MBC induced behavioral reactions in the polyps (increase of closed polyps with increased concentrations), decreased photosynthetic efficiency and the number of endosymbionts. Beside the polyp behavioural response, tested organic UV filters proven to have potential to induce coral bleaching. Further ecotoxicological studies should be undertaken with other compounds and with different coral species, to evaluate the effect of these emergent contaminants on coral reefs, and identify UV filter compounds less harmful to the environment.
Author: Jessica Mota
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDG: Life below water
Open Access status: green
OpenAlex ID: W2887762325