CO2 and Temperature Effects on the Early Life-Stages of an Important Northwest Atlantic Forage Fish, Atlantic Silverside (Menidia menidia)

Ocean conditions are changing along with the earth's climate due to anthropogenic additions of greenhouse gases such as CO₂ into the atmosphere. Approximately one-third of the total CO₂ emitted is absorbed by the ocean surface waters, making the ocean more acidic and altering its carbonate chemistry. Scientists seek to understand how these elevated thermal and CO₂ conditions might affect current and future oceans and their living marine resources (LMRs). LMRs are essential to the sustenance as well as the economies of coastal nations worldwide. In addition to the understanding of how these changes might affect commercially important fish taxa, knowledge of the effects on the fish that comprise the prey base that support commercially important fishes is also critical. Atlantic silverside (Menidia menidia) is a key forage fish of estuarine habitats of the Northwest Atlantic and is an essential prey for many economically important piscivorous fish and shellfish such as striped bass (Morone saxatilis) and blue crab (Callinectes sapidus). We evaluated the survival and developmental rates of embryos, and the sizes of early larvae of Atlantic silverside when raised at a range of different constant CO₂ levels at two temperatures. Survival tended to decrease with increasing CO₂ at both temperatures. Developmental rate and condition at hatching (yolk quantity) varied with CO₂ but the pattern of variation differed at the two temperatures, suggesting an interaction between CO₂ and thermal environment. Our experimental approach and these data give insights into the sensitivity, resilience, and potential complexity of this inshore fish to warmer and more acidic future oceans.