Browsing by Author "Day, J H O"

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    A study of the Hyperiid Amphipoda in the waters off the east and south coasts of the Republic of South Africa in relation to prevailing hydrological conditions
    (1967) Dick, Roy Ian; Day, J H O
    During the International Geophysical Year, 1957 - 1958, it was decided that the hydrographic frigate, S.A.S. "Natal", as part of the South African contribution, should undertake a number of oceanographic cruises off the east and south coasts of the Republic of South Africa. Thus during 1958 three cruises were carried out in February and March, May, and August, during which a. total of eighty-four oceanographic stations were occupied. Sixteen were occupied in the first cruise and thirty-four each in the second and third cruises. The stations were located on "lines" normal to the coast at Durban, Port Shepstone, Port St. Johns, Bashee River, East London, Kowie River, Port Elizabeth, and Cape Seal. In the first cruise only four lines were worked and of these, the first three contained three stations each while the fourth (Port Elizabeth line) contained six stations. The first station (NGY.1) was not located on any line and was used for gear testing. In the second and third cruises the minimum number of stations per line was increased to four while the number on the Port Elizabeth line remained at six. At each station both biological and hydrological sampling was carried out. The zooplankton samples were sorted into major taxonomic groups (e.g. Hyperiid amphipods) in the 1aboratory,after determination of the settled- and displacement volumes in the case of samples collected with N.70 nets. It is this.materia1 that formed the basis of this study. The investigation was undertaken with the following a1ms in mind: (i) To further the knowledge of the Hyperiid Amphipoda present in the waters off the east and south coasts of the Republic. (ii) To extend the knowledge. of the world geographic distribution of' hyperiids and clarify the position regarding the alleged cosmopolitan status and wide tolerances of many species. (i1i) To define more precisely the hydrological tolerances of hyperiid amphipods and assess ·their value as "indicator species", either alone or in association with other hyperiids or members of other taxomomic groups in the zooplankton. (iv) To determine the extent to which similar hydrological tolerances govern interspecific association in the hyperiids.
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    A study of the phytoplankton of the South Western Indian Ocean
    (1964) Taylor, F J R; Schelpe, E A C L E; Day, J H O
    Although the phytoplankton of the waters off the west coast of South Africa (the Benguela Current region) has been the subject of several detailed studies in the past, data on that of the S.W. Indian Ocean has been almost entirely restricted to incidental references in the reports of expeditions which have passed through the area. Consequently, little has been known of the species composition and distribution of the phytoplankton, and nothing of its seasonal fluctuations. This study was designed to provide a broad picture of the phytoplankton of the area, the primary objective being a critical determination of the species composition. The material was collected by the S.A.S. Natal on four seasonal cruises in the area as a contribution to the International Indian Ocean Expeditions. A net-sampling technique was used to provide the maximum amount of material for quantitative analysis. The phytoplankton was found to be extremely rich in variety, 402 taxa being identified from the 98 samples collected. Of these 233 were diatom taxa, 157 dinoflagellate taxa, and the remainder being composed of members of the Chrysophyeeae (coccolithophorids), Cyanophyceae and Xanthophyceae. These are listed in the systematic section together with original references and other references used by the author for their identification. The local and general distributions or the taxa are described and many of the taxa are illustrated by line drawings or microphotographs. 5 new species are described, as well as 1 new variety, and it was found necessary to provide new names for several species. Full systematic details are given for all new or rare taxa.