Microplankton from the Finnish Waters during the Month of May 1912. 



37 



the production takes place in the Upper layers. Either the organisms must hâve sunk, 

 or they have been brought dowöwards by vertical circulation. 



Consequently the plankton-distribution too indicates the mixing of the water-layers 

 just as the hydrographical data show it. 



CHAPTER IIT. 



REMARKS ON THE CONDITIONS OF LIFE AND THE QUALITY 



OF THE PLANKTON. 



SALINITY. 



At all the stations the salinity was low, varying in the samples examined between 

 3,68 °/ 00 (station F 41, mètres) and 9,47 °/ 00 (station F 61, 80 mètres). The sali- 

 nities of the water at the bottom were as follows (table V): 



Table V. Salinities of the bottom. 



Sotne of the species found can live in water of rather différent salinity, while other 

 forms are very sensible to différences of salinity. 



We may mention some of the euryhaline species, viz: 



Chaetoceras debile 

 Skeletonema costatum 

 Glenodinium bipes 

 Laboea sp. 



Lohman niella oviformis 

 Mesodinium rubrum 

 Tintinnopsis beroidea 

 Ebria tripartita. 



N:o 5. 



