Siliceous nanoplankton. II. Newly discovered cysts and abundant choanoflagellates from the Weddell Sea, Antarctica

TY - JOUR

T1 - Siliceous nanoplankton. II. Newly discovered cysts and abundant choanoflagellates from the Weddell Sea, Antarctica

AU - Silver, M. W.

AU - Mitchell, J. G.

AU - Ringo, D. L.

PY - 1980/10

Y1 - 1980/10

N2 - Siliceous choanoflagellates and previously undescribed, siliceous cyst-like spheroids (in the size range 2.5 to 15 μm) were found below sea-ice in the Weddell Sea and studied with scanning electron microscopy. Cell counts from water samples obtained over a 10,000 km area indicated that both spheroids and choanoflagellates were abundant in the upper 100 m of the water column, averaging about 105 cells l-1. The large numbers of phagotrophic choanoflagellates suggest that bacterioplankton-picoplankton food chains are important and may indicate the presence of longer, more complex trophic networks than previously considered in Antarctic waters. Circumstantial evidence suggests that the spheroids may be the cysts of choanoflagellates; if so, the production of siliceous cysts by members of this enigmatic taxon may be of considerable interest in discussions of the phylogenetic position of the group in relation to the algae and the metazoans. Similar cysts were found simultaneously in the North Pacific Ocean (see preceding paper: Booth et al. 1980), and recently we have discovered the cysts in the upwelling area of the eastern tropical Pacific Ocean. The occurrence of the cyst in such geographically distant localities suggests that they have a worldwide distribution. Since the minute cysts are easily overlooked on the light microscope, their recognition and further study undoubtedly require the electron microscopic examination of plankton samples.

AB - Siliceous choanoflagellates and previously undescribed, siliceous cyst-like spheroids (in the size range 2.5 to 15 μm) were found below sea-ice in the Weddell Sea and studied with scanning electron microscopy. Cell counts from water samples obtained over a 10,000 km area indicated that both spheroids and choanoflagellates were abundant in the upper 100 m of the water column, averaging about 105 cells l-1. The large numbers of phagotrophic choanoflagellates suggest that bacterioplankton-picoplankton food chains are important and may indicate the presence of longer, more complex trophic networks than previously considered in Antarctic waters. Circumstantial evidence suggests that the spheroids may be the cysts of choanoflagellates; if so, the production of siliceous cysts by members of this enigmatic taxon may be of considerable interest in discussions of the phylogenetic position of the group in relation to the algae and the metazoans. Similar cysts were found simultaneously in the North Pacific Ocean (see preceding paper: Booth et al. 1980), and recently we have discovered the cysts in the upwelling area of the eastern tropical Pacific Ocean. The occurrence of the cyst in such geographically distant localities suggests that they have a worldwide distribution. Since the minute cysts are easily overlooked on the light microscope, their recognition and further study undoubtedly require the electron microscopic examination of plankton samples.

UR - http://www.scopus.com/inward/record.url?scp=0000323550&partnerID=8YFLogxK

U2 - 10.1007/BF00391878

DO - 10.1007/BF00391878

M3 - Article

AN - SCOPUS:0000323550

SN - 0025-3162

VL - 58

SP - 211

EP - 217

JO - Marine Biology

JF - Marine Biology

IS - 3

ER -