From these data no marked trend of stratification of the seston components 

 in the bottom water can be found. The water depth seems to have more in- 

 fluence on it than has the kind of bottom substrate. 



The dominant proportion of phytoplankton biomass was formed by small 

 (20 to 28 microns long) and medium (29 to 56 microns long) peridinians. 

 Small, naked flagellates (8 to 12 microns long) were found very frequently, 

 but did not contribute much to the biomass. Centric diatoms formed at least 

 12 to 207o of total biomass. During the first days of observation (October 19. 

 to 21.) this percentage was higher (about 30%). The table shows that the 

 standard deviation in phytoplankton carbon is much higher than in direct 

 analyses of the seston. 



There was no good correlation between seston and carbon values. The 

 correlation coefficient was best between total seston (column 1) and direct 

 determined organic carbon (column 5), being + 0.38, compared with a coefficient 

 of + 0,35 between the acid treated seston (column 2) and the organic carbon. 

 Correlation between seston and nitrogen were worse. 



RECOMMENDATIONS 



It is obvious that there was a need for parallel plankton and seston investi- 

 gations from the surface and of hydrographical observations at the same time. 

 The investigations should extend over a longer period. Changes of hydro- 

 graphical and chemical conditions in the water - such as the extreme turbidity 

 after the heavy rainfalls prior to Mission 15 - would provide a good 

 opportunity to observe the responses of plankton development and of the 

 significance of the seston for the coral reef fauna. 



VI-278 



