. IO EAST Fig. 95. Distribution of (A) Planktoniella, (B) Goniaulax, and (C) Chaetoceros between Mowe Point and Sylvia Hill, survey I, March 1950. Where there is no shading none was recorded. The lightest shading represents estimates of < io4 per net haul, the next io45, and so on. Observations on discoloured water Large areas of the sea near Walvis Bay were discoloured ' blackish' by diatoms during our first survey, the general appearance being dark green to black, and opaque, very similar to that described in arctic regions by Brown (1868) and found by him to be due to diatoms also. In t

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. IO EAST Fig. 95. Distribution of (A) Planktoniella, (B) Goniaulax, and (C) Chaetoceros between Mowe Point and Sylvia Hill, survey I, March 1950. Where there is no shading none was recorded. The lightest shading represents estimates of < io4 per net haul, the next io4~5, and so on. Observations on discoloured water Large areas of the sea near Walvis Bay were discoloured ' blackish' by diatoms during our first survey, the general appearance being dark green to black, and opaque, very similar to that described in arctic regions by Brown (1868) and found by him to be due to diatoms also. In the Benguela current we found the inshore chaetocerids, especially Chaetoceros didymum and Aster ionella japonica, to be the species chiefly responsible. Within this same region, however, were many more localized brownish or khaki-coloured discolorations, forming irregular bands and streaks roughly parallel with the coast, sometimes associated with foam streaks and lanes of dead and dying macroplankton—mainly ctenophores and salps—at the surface. A minor fish mortality had occurred near Walvis Bay just before we got there. Three samples from some of these more strikingly discoloured waters were obtained off Sandwich Harbour (about 220 30' S. and 10 sea-miles offshore). Subsequent detailed microscopic examination of these yielded the results shown in Tables 18, 19 and 20.