Planktonic diatoms of the genus Chaeotoceros Ehr. from Antarctic waters

HERNÁNDEZ-BECERRIL, D.U.; FERRARIO, M.E.; GARIBOTTI, I.A.

Atenas, Grecia

Simposio; 16th International Diatom Symposium; 2000

International Society for Diatom Research

Planktonic diatoms of the genus Chaetoceros are common in Antarctic waters, and although they have been frequently cited in this region, some species still remain relatively unknown. Preserved phytoplankton samples are the basis of this work, which were collected in various oceanographic cruises, during different seasons in 1985, 1996 and 1999, from several locations of the north coast of the Antarctic Peninsula, the Weddell Sea and the Gerlache Strait; the material was obtained using net (30 mm mesh) and fixed with formalin. This material has been treated conventionally for its observation in light and electronic microscopy. We have identified and studied 17 taxa: 14 species and 3 taxonomic forms, as well as a number of morphotypes and also species producing resting spores. We found the most commonly cited species in our material, including some of the so-called "ice community": Chaetoceros atlanticus, C. criophilus, C. dichaeta and C. radiculus. Some new observations by electron microscopy of the species C. castracanei and C. schrimperianus are made in this study. Diversity of the genus is not high in Antarctic waters when compared with tropical or temperate ones. Local and seasonal distributions are shown, and taxonomic problems as well as biogeography of some species are discussed.