We evaluated a 10year time series of O-18 and C-13 records from three planktic foraminifers (Neogloboquadrina pachyderma, Globigerina umbilicata, and Globigerinita glutinata) in the Bering Sea and central subarctic Pacific with a focus on their responses to environmental changes. Foraminiferal O-18 followed the equilibrium equation for inorganic calcite, with species-specific equilibrium offsets ranging from nearly zero (-0.02 for N.pachyderma and -0.01 for G.umbilicata) to -0.16 (G.glutinata). Equilibrium offsets in our sediment trap samples were smaller than those from plankton tow studies, implying that foraminiferal O-18 was modified by encrustation during settling. Habitat/calcification depths varied from 35-55m (N.pachyderma and G.umbilicata) or 25-45m (G.glutinata) during warm, stratified seasons to around 100m during winter, when the mixed layer depth increases. Unlike O-18, foraminiferal C-13 showed species-specific responses to environmental changes. We found a dependency of C-13 in G.umbilicata on CO32- concentrations in ambient seawater that agreed reasonably well with published laboratory results, suggesting that C-13 of G.umbilicata is subject to vital effects. In contrast, C-13 of N.pachyderma and G.glutinata are likely affected by other species-specific biological activities. Seasonal flux patterns reveal that fossil records of N.pachyderma and G.glutinata represent annual mean conditions, whereas that of G.umbilicata most likely indicates those of a specific season. Because none of these three taxa was abundant from December to February, their fossil records likely do not reflect isotope signals from cold seasons.