This study aims to elucidate the long-term physiological impacts of ocean acidification on a key seafood species. The Mediterranean mussel Mytilus galloprovincialis, was subjected to three pH conditions over a period of six months: two pH values within the present range of natural variability (pHT: 8.10 and 7.80) and a lower pH condition (pHT: 7.50) relevant in the context of near-future ocean acidification. A comprehensive assessment was conducted at the conclusion of the fourth and sixth months and encompassed a suite of physiological endpoints, including mortality, oxygen consumption, clearance rate, total haemocyte count (THC), nutritional content analysis, and polonium-210 (210Po) depuration rates. The findings revealed a marked decrease in survival rates at pH 7.50 compared with those at pH 8.10 and 7.80 after six months of exposure. This was associated with a significant increase in THC and a decrease in lipid content. No significant pH effects were observed for other endpoints (namely clearance rate, condition index, oxygen consumption rate, protein and carbohydrate contents, and 210Po). While the lack of response to low pH at some of these physiological endpoints may be a consequence of a lack of statistical power, our data clearly demonstrate the effects of low pH on the survival, THC, and lipid content of M. galloprovincialis. Such effects on a species' overall fitness have the potential to negatively impact this key seafood species, associated ecosystems, and the socioeconomic dynamics of communities depending on this resource.
Keywords: (210)Po; Chronic exposure; Mussel; Ocean acidification; Physiology; Survival.
Copyright © 2025 Elsevier Ltd. All rights reserved.