Early exposure of bay scallops (Argopecten irradians) to high CO₂ causes a decrease in larval shell growth.

Area of Science:

• Marine Biology
• Ecology
• Environmental Science

Background:

• Ocean acidification, driven by elevated pCO₂, lowers seawater pH and calcium carbonate saturation state (Ω).
• Marine invertebrate larvae are particularly susceptible to environmental stressors like ocean acidification.
• Previous studies indicate negative impacts on bivalve molluscs' fertilization and development.

Purpose of the Study:

• To investigate the effects of high CO₂ exposure on bay scallop (Argopecten irradians) larvae.
• To assess if early exposure to high CO₂ has persistent effects on larval development, even after a switch to ambient conditions.
• To evaluate impacts on larval survival and shell growth.

Main Methods:

• Exposure of bay scallop larvae to high CO₂ (pH 7.39, Ω(ar) 0.74) and ambient CO₂ (pH 7.93, Ω(ar) 2.26) conditions.
• Larvae were monitored from 12 hours to 7 days old.
• A treatment group experienced a switch from high CO₂ to ambient CO₂ after 3 days.

Main Results:

• Larval survival was consistently lower in high CO₂ conditions, significantly reduced by day 1.
• Shell length was significantly smaller in high CO₂ treated larvae, reduced by 11.5% by day 7.
• Short-term high CO₂ exposure effects on shell size persisted even after transfer to ambient conditions.

Conclusions:

• Ocean acidification poses a significant threat to the survival and growth of bay scallop larvae.
• Early life stages of marine invertebrates show lasting sensitivity to ocean acidification.
• Mitigation of CO₂ emissions is crucial to protect vulnerable marine populations.