Notes on variation of diatoms and silico flagellates in the South Atlantic Ocean
van der Spoel, S.; Hallegraeff, G.M.; Van Soest, R.W.M. (1973). Notes on variation of diatoms and silico flagellates in the South Atlantic Ocean. Neth. J. Sea Res. 6(4): 518-541
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579; e-ISSN 1873-1406, more
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| Authors | | Top |
- van der Spoel, S.
- Hallegraeff, G.M.
- Van Soest, R.W.M., more
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| Abstract |
This paper contains the results of studies on the seasonal and latitudinal variation of certain phytoplankton organisms from the Southern Atlantic Ocean and the adjacent sector of the Antarctic Ocean, based on samples taken by the "Willem Barendsz" Cruise 1959-1960. Particularly the study of the diatoms Fragiliaropsis kerguelensis, Coscinodiscus lentiginosus, C. minor, Asteromphalis hookeri and the silicoflagellate Distephanus speculum has revealed new and interesting facts, concerning the theory of Wimpenny (1936, 1946, 1966) of the influence of temperature on the size variations of planktonic diatoms, although no definite support or negation of this theory could be given. Next to temperature, certainly other factors as the population density and the nutrient content of the seawater have been found to influence the size of the diatoms. No support has been found for the theory that the intensity of grazing might be responsible for size variations in diatoms. The hitherto known range of Fragilariopsis kerguelensis has been extended to 30°N; a more or less continuous series of samples from the Subtropical Convergence at 40°S to 30°N showed the species to be scarce but nearly always present in this area. Asteromphalus heptactis, a (6+1) rayed form, could be synonymized with A. hookeri, as it proved to be only an ecotype or morph of this species. The (3+1) rayed form of A. hookeri recorded in this paper is new to science. |
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