Effects of high pCO2 on early life development of pelagic spawning marine fish.

The present study investigated the effect of elevated pCO₂ on the development of early stages of the pelagic spawning marine fish Solea senegalensis, Diplodus sargus and Argyrosomus regius. Eggs and larvae were reared under control (pH 8.0, ~570 μatm) and two elevated pCO₂ conditions (pH 7.8, ~1100 μatm; pH 7.6, ~1900 μatm) until mouth opening (3 days post-hatching). Egg size did not change with exposure to elevated pCO₂, but hatching rate was significantly reduced under high pCO₂ for all three species. Survival rate was not affected by exposure to increased pCO₂, but growth rate was differently affected across species, with A. regius growing faster in the mid-level pCO₂ treatment compared with control conditions. S. senegalensis and A. regius hatched with smaller yolk sacs under increased pCO₂ but endogenous reserves of D. sargus were not affected. Otoliths were consistently larger under elevated pCO₂ conditions for all the three species. Differences among egg batches and a significant interaction between batch and pCO₂ suggest that other factors, such as egg quality, can influence the response to increased pCO₂. Overall, the results support the occurrence of a species-specific response to pCO₂, but highlight the need for cautious analysis of potential sensitivity of species from unreplicated observations. [ABSTRACT FROM AUTHOR]