Microzooplankton and tintinnid species-specific assemblage structures: patterns of distribution and year-to-year variations in the Weddell Sea (Antarctica).

BOLTOVSKOY, D.; ALDER V.A.

JOURNAL OF PLANKTON RESEARCH

Oxford University Press

Año: 1992 vol. 14 p. 1405 - 1423

0142-7873

  Silicoflagellates, large heterotrophic dinoflagellates, radiolarians, tintinnids and microcrustaceans were counted in 72 screened (15 µm) samples retrieved at 0 to 150 m from the Weddell Sea in January 1989. Tintinnid species were identified and for all groups biomass estimates were carried out on the basis of measurements of cell-dimensions. Dinoflagellates dominated the microheterotrophic community at all stations and depths (65% of overall microzooplanktonic carbon in the 0-150 m interval), followed by the tintinnids (18%), microcrustaceans (16%), and radiolarians (1%). All groups, with the exception of silicoflagellates, peaked noticeably in the vicinity of the southern end of the transect (76°-77°S). Relationships between concentrations of chlorophyll a and microzooplanktonic biomass were present yet not altogether consistent, but both phyto- and microzooplankton seemed to generally respond to regional enhancements associated with the ice-edge. Comparison with similar Weddell and Weddell-Scotia data retrieved in Feb.-Mar. 1987 and in Nov. 1988-Dec. 1989, respectively, are highly coherent in terms of microplanktonic abundances, their geographic and vertical distribution patterns, and the specific makeup and distribution of tintinnid assemblages. Analyses of the oral diameters of tintinnid morphotypes suggest that the latitudinal and vertical distribution of their 5 dominant taxa (which account for over 90% of all individuals) is structured so as to maximize resource partitioning.