M. Quevedo et R. Anadon, Spring microzooplankton composition, biomass and potential grazing in the central Cantabrian coast (southern Bay of Biscay), OCEANOL ACT, 23(3), 2000, pp. 297-309
Microzooplankton abundance, biomass and composition were investigated in th
e coastal waters of Asturias (southern Bay of Biscay) in May 1996. Abundanc
e ranged from 0.7 x 10(3) to 8.5 x 10(3) cell.L-1 The protists community wa
s dominated by aloricate ciliates averaging 82 % of microheterotrophs. Smal
l aloricate ciliates, below 20 mu m in size, contributed 63 % to total cili
ate abundance. Carbon biomass ranged from 2.4 to 15.4 mgC.m(-3), averaging
23 % of phytoplankton biomass. Aloricate ciliates were also the dominant co
mponent of biomass (56.2 %), but the importance of copepod nauplii increase
d in terms of carbon, averaging 28.5 % of total biomass. Microzooplankton b
iomass was significantly correlated with Chi a concentration in the water c
olumn. Theoretical estimates of the grazing impact of the microzooplankton
community on phytoplankton were calculated and resulted in an average value
of 28.3% of phytoplankton standing stock potentially consumed per day. Cho
reotrich ciliates were the most important potential grazers in the study (1
3.7% of standing stock) followed by metazoan nauplii (6.3 %). The potential
microzooplankton impact on phytoplankton was consistent with the large siz
e of primary producers during diatom spring blooms, like the one found in t
his study. The validity of theoretical estimates of microzooplankton grazin
g impact, as well as the importance of including metazoan larvae in coastal
microzooplankton community studies are discussed. (C) 2000 Ifremer/CNRS/IR
D/Editions scientifiques et medicales Elsevier SAS.