Ocean acidification conditions and warmer temperatures reduced the survival, development, growth, and lipid synthesis of hard clam and bay scallop larvae. During the juvenile life stages, ocean acidification negatively affected juvenile eastern oysters and bay scallops, but not hard clams. Larvae were substantially more vulnerable to ocean acidication than juveniles were. These findings suggest that current and future increases in temperature and carbon dioxide are likely to have negative consequences for coastal bivalve populations. (Laboratory study)