Mollusks are a diverse group of animals vital to fisheries; shelled mollusks like clams and oysters are particularly vulnerable to the effects of acidification.
Species Role
Mollusks are invertebrates, and their body forms vary widely from clams and scallops, to snails and slugs, to octopus and squid. Not only are mollusks a highly diverse group of animals, they are also the basis of a number of major world fisheries and a large component of global marine aquaculture.
Mid-Atlantic Mollusk Fisheries
In the Mid-Atlantic, bivalve and cephalopod mollusks – clams, oysters, scallops and squid – are among the largest and most valuable commercial fisheries. Bivalve clams and oysters are also the foundation of the majority of marine aquaculture produced in the Mid-Atlantic region.
Many mollusks have shells made of calcium carbonate, a material that can be vulnerable to low pH or acidified conditions. In a recent review of sensitivity of species to changing climate, the shellfisheries of the Mid-Atlantic were identified as particularly at high risk for negative impacts due to both acidification and temperature changes.
Acidification Threats to Bivalve Larvae
The larval stages of bivalves are especially sensitive to changes in pH and alkalinity, because their shells are thin, newly developing, and made of a highly soluble form of calcium carbonate called aragonite.
Low pH and undersaturation of calcium carbonate can easily dissolve thin aragonite shells and have been shown in laboratory experiments to lead to reduced survival and growth for bivalve larvae. In the Pacific and Northeast, undersaturation of calcium carbonate has negatively impacted shellfish hatchery production.
Challenges of Acidification for Bivalves
Research suggests that later life stages of bivalves, like juvenile clams and oysters, may still be susceptible to OA. The sensitivity of bivalves to OA are highly variable among species and life stages and further research is required to understand how the impacts of OA interact with impacts from other environmental conditions like temperature and salinity.
Nonetheless, the sensitivity of larval and young juvenile bivalves has important consequences in terms of population stability of these economically and ecologically important species.
Shellfish and Coastal Resilience
Bivalve shellfish are filter-feeders and important coastal ecosystem builders, and are often the focus of restoration and ecosystem resilience planning. To effectively implement coastal resilience or restoration priorities that include shellfish, it is imperative to better understand the ways that future acidified conditions will interact with these species throughout their life cycle.
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Schwaner C, Barbosa M, Schwemmer TG, Pales Espinosa E, Allam B. Increased Food Resources Help Eastern Oyster Mitigate the Negative Impacts of Coastal Acidification. Animals. 2023 Mar 25;13(7):1161. https://doi.org/10.3390/ani13071161
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