Increased surface seawater pCO2 observed in the eastern Bering Sea shelf (long 168¿W--160¿W; lat 54¿N--68¿N) were examined in relation to blooms of the coccolithophorid Emiliania huxleyi, using data obtained from R/V Mirai cruises once or twice annually (August--October 1998--2002). A principal component analysis demonstrated that there are two spatial scales of pCO2 variability associated with E. huxleyi blooms. One is a small-scale variation (~0.2¿ in latitude), which shows a decrease of pCO2 by 18 ¿atm relative to surrounding waters. The other is a large-scale variation (~10.0¿ in latitude), with spatial gradient in pCO2 of up to 250 ¿atm. Detailed analyses show that the large-scale variation is associated with diatom blooms, while the small-scale variation is associated with coccolithophorid blooms with a calcification:photosynthesis = 1.0, and thus that seawater pCO2 is affected by the composition of marine ecosystems and its response to climate variability. SST rise also contributed to increased pCO2.