Research Technical Report

Intra and Interannual Variation in Euphausiid Populations Within the Monterey Bay

Marinovic, B. (December 1997)

Presentation at Western Society of Naturalists Annual Meeting, Monterey, CA

ABSTRACT

Intra and inter annual polulation demography of euphausiid species within Monterey Bay were investigated during the spring, summer and fall of 1996 and 1997. Populations were sampled through plankton tows conducted in May, Aug, Sep and Nov of 1996 and monthly from Apr-Oct in 1997. Distinct patterns of seasonal reproduction were evident in both 1996 and 1997. In addition, major differences in the relative abundance as well as species composition of euphausiid populations occurred between 1996 and 1997 which appear to be correlated to variation in upwelling between the two years. CTD data as well a major differences in indicator taxa suggested a pronounced and markedly earlier onset of oceanic conditions in 1997 relative to 1996 which in tum corresponded to a major decrease in euphausiid abundance within Monterey Bay.