Abstract:
Ecological effects of populations of the salp Cyclosalpa bakeri were studied in late
summer of 1984, 1987 and 1988 dunng 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.
