Impairment of swimming performance in Tritia reticulata (L.) veligers under projected ocean acidification and warming scenarios

Effects of ocean acidification and warming on apoptosis and immune response in the mussel Mytilus coruscus

Ocean acidification and warming are significant stressors impacting marine ecosystems, exerting profound effects on the physiological ecology of marine organisms. We investigated the impact of ocean acidification and warming on the immune system of mussels, focusing on the regulatory mechanisms of intrinsic and extrinsic apoptosis. The study explored the effects on the immune response ability of mussels (Mytilus coruscus) after 14 and 21 days under combined conditions of different temperatures (20 °C and 30 °C) and pH (8.1 and 7.7), as expected for the year 2100. The experimental results indicated that ocean acidification and warming have significant interactive effects on various immune parameters of M. coruscus. Specifically, ocean acidification and warming lead to an increase in ROS (Reactive Oxygen Species), apoptosis, TNF-α (Tumor Necrosis Factor-alpha), TGF-β (Transforming Growth Factor-beta), Caspase-8, and a decrease in IL-17 (Interleukin 17). These findings suggest that ocean acidification and warming trigger an immune inflammatory response in mussels. Regulating immune functions through apoptosis pathways may be a crucial coping mechanism in response to environmental variations, but its long-term impact on population health and sustainability remains uncertain. Our findings offer important insights into the complex interactions between bivalve immune responses and environmental stressors. This also underscores the need for further research into the adaptive capabilities of marine organisms facing the compounded challenges of ocean acidification and warming.

Behavioral and physiological effects of ocean acidification and warming on larvae of a continental shelf bivalve

The negative impacts of ocean warming and acidification on bivalve fisheries are well documented but few studies investigate parameters relevant to energy budgets and larval dispersal. This study used laboratory experiments to assess developmental, physiological and behavioral responses to projected climate change scenarios using larval Atlantic surfclams Spisula solidissima solidissima, found in northwest Atlantic Ocean continental shelf waters. Ocean warming increased feeding, scope for growth, and biomineralization, but decreased swimming speed and pelagic larval duration. Ocean acidification increased respiration but reduced immune performance and biomineralization. Growth increased under ocean warming only, but decreased under combined ocean warming and acidification. These results suggest that ocean warming increases metabolic activity and affects larval behavior, while ocean acidification negatively impacts development and physiology. Additionally, principal component analysis demonstrated that growth and biomineralization showed similar response profiles, but inverse response profiles to respiration and swimming speed, suggesting alterations in energy allocation under climate change.

The role of ligand-gated chloride channels in behavioural alterations at elevated CO2 in a cephalopod

Projected future carbon dioxide (CO2) levels in the ocean can alter marine animal behaviours. Disrupted functioning of γ-aminobutyric acid type A (GABAA) receptors (ligand-gated chloride channels) is suggested to underlie CO2-induced behavioural changes in fish. However, the mechanisms underlying behavioural changes in marine invertebrates are poorly understood. We pharmacologically tested the role of GABA-, glutamate-, acetylcholine- and dopamine-gated chloride channels in CO2-induced behavioural changes in a cephalopod, the two-toned pygmy squid (Idiosepius pygmaeus). We exposed squid to ambient (∼450 µatm) or elevated (∼1000 µatm) CO2 for 7 days. Squid were treated with sham, the GABAA receptor antagonist gabazine or the non-specific GABAA receptor antagonist picrotoxin, before measurement of conspecific-directed behaviours and activity levels upon mirror exposure. Elevated CO2 increased conspecific-directed attraction and aggression, as well as activity levels. For some CO2-affected behaviours, both gabazine and picrotoxin had a different effect at elevated compared with ambient CO2, providing robust support for the GABA hypothesis within cephalopods. In another behavioural trait, picrotoxin but not gabazine had a different effect in elevated compared with ambient CO2, providing the first pharmacological evidence, in fish and marine invertebrates, for altered functioning of ligand-gated chloride channels, other than the GABAAR, underlying CO2-induced behavioural changes. For some other behaviours, both gabazine and picrotoxin had a similar effect in elevated and ambient CO2, suggesting altered function of ligand-gated chloride channels was not responsible for these CO2-induced changes. Multiple mechanisms may be involved, which could explain the variability in the CO2 and drug treatment effects across behaviours.