ABSTRACT: Ecological effects of populations of the salp Cyclosalpa bakeri were studied in late summer of 1984, 1987 and 1988 during the Subarctic Pacific Ecosystem Research (SUPER) project at Station P in the northeast Pacific. Salps occurred largely in the top 60 m, with biomass values ranging from 76 to 3621 mg C m^-2. Three approaches were taken to estimate the grazing impact of these populations. C. bakeri removed from 1.6 to 136.6% of daily primary production and 1.3 to 56.8% of the diatom stocks in August 1988. On average, feeding rates of the salps predicted clearance of all particles >=5.0 µm from 1.2 to 49.2% of the water column per day in 1984 and 1988. Although excretion of dissolved N appears negligible, production of fecal C and N can be high, as much as 875 mg C and 110 mg N m^-2 d^-1 at the highest population density sampled. Although the salps probably do not have a significant grazing impact on the small cells (<=5.0 µm) which are responsible for most of the production, they may be important in controlling populations of diatoms which typically occur in late summer at Station P.

KEY WORDS: Salps · Grazing · Subarctic Pacific · Station P · Diatoms

Published in MEPS Vol. 157 (1997) on October 16
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1997