pH stress in bivalves: Effects on growth, calcification, and metabolic processes

Bivalves, which are vital to aquatic ecosystems and aquaculture, are highly susceptible to pH fluctuations caused by ocean and freshwater acidification. This review summarizes the physiological responses of various bivalve species to changes in pH, including effects on growth, shell calcification, metabolism, respiration, feeding, and excretion. Ocean acidification reduces the availability of carbonate ions, which inhibits shell formation and growth and can divert energy toward pH regulation. Species sensitivity varies: marine bivalves are particularly vulnerable to slight decreases in pH, whereas many freshwater species exhibit greater resilience due to their adaptation to variable habitats. Acidic conditions can induce metabolic depression to conserve energy or increase energy demands for maintaining homeostasis, resulting in reduced growth, higher mortality, and impaired reproduction. Feeding rates are highly sensitive to pH, with most bivalves showing optimal activity within a narrow pH range and reduced feeding under acidic stress. Understanding species-specific vulnerabilities and pH tolerance mechanisms is crucial for effective conservation in an increasingly acidified environment.

کلیدواژه ها:

Ocean acidification ، bivalve physiology ، calcification ، pH tolerance ، metabolic adaptation