Native and introduced clams biochemical responses to salinity and pH changes.

Area of Science:

• Marine Biology
• Ecotoxicology
• Climate Change Biology

Background:

• Projected 2100 climate scenarios indicate significant shifts in aquatic salinity and pH.
• These environmental changes may facilitate the invasion of new ecosystems by non-native species.
• Understanding species-specific physiological responses is crucial for predicting ecosystem dynamics.

Purpose of the Study:

• To assess the physiological and biochemical impacts of salinity and pH changes on native Ruditapes decussatus and introduced Ruditapes philippinarum clams.
• To compare the stress responses and adaptive capacities of native versus invasive clam species under simulated climate change conditions.

Main Methods:

• Evaluation of oxidative stress biomarkers.
• Measurement of metabolic activity indicators.
• Assessment of osmoregulation capacity through enzyme activity.
• Comparative analysis of native and introduced clam species.

Main Results:

• Extreme salinities caused mortality in both clam species; low pH (7.3) was survived by all.
• Both species utilized glycogen reserves for cellular protection under salinity stress.
• Ruditapes philippinarum exhibited superior antioxidant enzyme induction and carbonic anhydrase activity under extreme salinities compared to Ruditapes decussatus.
• Low pH induced greater oxidative stress and upregulated antioxidant, detoxification, and osmoregulation mechanisms in R. philippinarum than in R. decussatus.

Conclusions:

• Salinity and pH fluctuations significantly alter the physiological and biochemical status of both native and invasive clam species.
• Ruditapes philippinarum demonstrates greater resilience to salinity changes, potentially conferring a competitive advantage in changing marine environments.
• Differential responses to low pH suggest varying vulnerabilities and adaptive potentials between native and introduced clam populations.