Increased surface seawater p CO 2 in the eastern Bering Sea shelf: An effect of blooms of coccolithophorid Emiliania huxleyi ?

Increased surface seawater p CO 2 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 p CO 2 variability associated with E. huxleyi blooms. One is a small‐scale variation (∼0.2° in latitude), which shows a decrease of p CO 2 by 18 μ atm relative to surrounding waters. The other is a large‐scale variation (∼10.0° in latitude), with spatial gradient in p CO 2 of up to 250 μ 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 p CO 2 is affected by the composition of marine ecosystems and its response to climate variability. SST rise also contributed to increased p CO 2 .