Austral winter distributions of large tintinnid and large sarcodinid protozooplankton in the ice-edge zone of the Weddell/Scotia Seas
Gowing, M.M.; Garrison, D.L. (1991). Austral winter distributions of large tintinnid and large sarcodinid protozooplankton in the ice-edge zone of the Weddell/Scotia Seas. J. Mar. Syst. 2(1-2): 131-141. https://dx.doi.org/10.1016/0924-7963(91)90019-Q
In: Journal of Marine Systems. Elsevier: Tokyo; Oxford; New York; Amsterdam. ISSN 0924-7963; e-ISSN 1879-1573, meer
Ook verschenen in:Nihoul, J.C.J.; Djenidi, S. (1991). Ice covered seas and ice edges: Physical, chemical and biological processes and interactions - Proceedings of the 22th International Liège Colloquium on Ocean Hydrodynamics. Journal of Marine Systems, 2. Elsevier Science Publishers: Amsterdam. 520 pp., meer
|  |
| Auteurs | | Top |
- Gowing, M.M.
- Garrison, D.L.
|
|
|
| Abstract |
Seasonal distribution and abundance data for large sarcodinid protozooplankton (Radiolaria, Foraminifera, Acantharia and the heliozoan Sticholonche spp.) and larger tintinnid ciliates (e.g., Laackmaniella spp.) are necessary for evaluating their roles in food webs and particle fluxes. As part of the Antarctic Marine Ecosystem Research in the Ice Edge Zone (AMERIEZ) project, we sampled these large (≥ 50 μm) protozooplankton in the winter ice edge zone of the Scotia/Weddell Seas. Organisms alive at the time of capture were counted in large volume (60 1) water samples from 5 paired depths in the upper 210 m from 17 stations. Relationships between abundances and environmental factors in ice-covered, ice edge, and open waters were assessed with correlation, cluster, and multidimensional scaling analyses.Mean abundances of large tintinnids were less than 3150 per m3, and mean abundances of the individual sarcodine groups were generally less than 1000 per m3. The most pronounced distributional patterns were related to depth. In general, large tintinnids were more abundant in the colder waters from 0-85 m, a zone encompassed by the mixed layer and the euphotic zone. Acantharians were more abundant in this upper zone only in ice-covered waters. Radiolaria (predominantly phaeodarians) and the heliozoan Sticholonche spp. were more abundant from 115 to 210 m, a zone of warmer, more saline water. Foraminiferan distributions showed little pattern with depth. Results of the cluster analyses also suggested that depth was the most significant effect determining similarity among assemblages of large protozooplankton at the 17 stations. The few correlations between abundances of the groups and chlorophyll a probably reflect relationships more complex than grazing.Abundances of large tintinnids were higher in surface waters under the ice than at the ice edge or in open water. This could result from their feeding on algal cells released from the base of the ice or it may be a result of higher populations in the outflow of Weddell Sea water. There were no consistent abundance patterns among large sarcodines that could be related to ice cover. It is suggested that the combination of low winter productivity, a dynamic environment, and slower growth rates of these large protozoans may prevent them from responding to local enhanced production with increased abundances in the winter ice edge zone. Furthermore, although there is enhanced productivity at the ice edge, this signal may not reach the protozooplankton groups most abundant in the water layer below the euphotic zone. |
|
