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RESEARCH PRODUCT

CO2 effects on behaviour and reproduction of nesting fish species

subject

description

Ocean acidification is a global phenomenon linked to the CO2 absorption by the surface of the sea. This increasing process leads to a rise of the CO2 partial pressure (pCO2) that changes the seawater chemistry. It is known that such changes have negative consequences for many marine organisms. However, the effects of acidification on fishes are yet poorly understood. Fishes have been hypothesized to be more physiologically tolerant to elevated CO2. Nevertheless, many researches have described severe effects of altered pCO2 levels on fish behaviour, especially during early life history stages, and only few authors have focused on fish reproduction. The aim of my Ph.D. research is to investigate the effects of different pCO2 levels on the reproduction of nesting fish species, with particular emphasis on reproductive behaviour and reproductive success, and on early life stages development. This research will be conducted in the Vulcano Island coast where a natural gradient of pH and CO2 exists, due to underwater volcanic emissions dominated by CO2. Preliminary observations on fish community composition in this place have shown different distribution patterns of the species along the pCO2 gradient. In particular, some species belonging to genus Symphodus display the same distribution pattern in high pCO2 levels (= ca. 1100 µatm) and in normal pCO2 levels (= ca. 400 µatm). The males of these species build elaborate nests in which several females spawn, and they could be more sensitive to the acidification effects due to territorial habits shown during their reproductive period.