Microbial community structure in the marginal ice zone of the Bellingshausen Sea

Autor: Michael A. Sleigh, Elaine S. Edwards, Peter H. Burkill
Rok vydání: 1998
Předmět:
Zdroj: Journal of Marine Systems. 17:87-96
ISSN: 0924-7963
DOI: 10.1016/s0924-7963(98)00031-1
Popis: Phytoplankton, bacteria and microzooplankton were investigated on a transect in the Bellingshausen Sea during the ice melt period in November-December 1992. The transect along the 858W meridian comprised seven stations that progressed . . from solid pack-ice 708S , through melting ice into open water 678S. The abundance, biomass and taxonomic composition were determined for each component of the microbial community. The phytoplankton was mostly dominated by diatoms, . y1 y1 particularly small - 20 mm species. Diatom abundance ranged from 66 000 cells l under the ice to 410 000 cells l in open water. Phytoplankton biomass varied from - 1 to 167 mg C m y3 , with diatoms comprising 89-95% of the total biomass in open water and autotrophic nanoflagellates comprising 57% under the ice. The standing stocks of autotrophs in the mixed layer ranged from 95 mg C m y2 under the pack-ice to 9478 mg C m y2 in open waters. Bacterial abundance in ice-covered and open water stations varied from 1.1 to 5.5 = 10 8 cells l y1 . Bacterial biomass ranged from 2.4 mg C m y3 under pack-ice to an average of 14 mg C m y3 in open water. The microzooplankton consisted mainly of aloricate oligotrich ciliates and heterotrophic dinoflagellates and these were most abundant in open waters. Their biomass varied between 0.2 and 54 mg C m y3 with a minimum at depth under the ice and maximum in open surface waters. Microheterotrophic standing stocks varied between 396 mg C m y2 under pack-ice and 3677 mg C m y2 in the open waters. The standing stocks of the total microbial community increased consistently from 491 mg C m y2 at the ice station to 13 155 mg C m y2 in open waters, reflecting the productive response of the community to ice-melt. The composition of the microbial community also . shifted markedly from one dominated by heterotrophs 82% of microbial stocks at the ice station to one dominated by . autotrophs 73% of microbial stocks in the open water. Our estimates suggest that the microbial community comprised . ) 100% of the total particulate organic carbon POC under the ice and 62-66% of the measured POC in the open waters. Resume ´´ L'etude concerne le phytoplancton, le microzooplancton et les bacteries sur une radiale dans la Mer de Bellingshausen a
Databáze: OpenAIRE
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