MICROPLANKTON 231 



enriched offshore community in the poorest sample. A tendency towards restriction of this group to 

 the transition zone had also been apparent on several of the lines worked during the first survey. 



Other main groups were very evenly distributed on the Mowe Point line during the second survey. 

 The quantities of Metazoa were moderately high, and considerable quantities of Seston were recorded, 

 suggesting that feeding and growth of the smaller plankton animals might be proceeding more uni- 

 formly and somewhat faster at this period than in the autumn. 



20° 



25°H 



S " 



o 

 u 



T 

 H 



30 



io 4 -io 5 [ 

 io 5 -io 6r 



MOWE POINT 



IO-IO " 



IO-IO 



IVALVIS BAY 



SURVEY: I 

 1 r 



EAST 



— T 1 1 



10° 15° 



Fig. 65. Distribution of the microplankton, estimated totals per net haul, survey II, 

 September-October 1950. (Station numbers are shown in Fig. 2.) 



On the northern intermediate line (Fig. 67) similar conditions prevailed, indicating that the relative 

 richness of offshore phytoplankton and general abundance of small zooplankton feeding voraciously 

 were features distinguishing the samples collected during the second survey from the ones from 

 corresponding first survey positions. 



The figures for the Walvis Bay line (Fig. 68) show a rich diatom plankton right inshore and a 

 secondary peak at station WS 1079. The work on this line was interrupted by a gale, so that some 

 considerable time elapsed between the working of this and the preceding inshore stations. There is 

 hydrological evidence (p. 1 88) supporting the view that surface-drift of inshore water during the interval 

 led to this apparent anomaly. In other respects the features of the microplankton distribution offshore 

 on this line during the second survey were similar to those found farther north: moderately high 



