32 



ASTRID CLEVE-EULER, QUANTITATIVE PLANKTON RESEARCHES IN THE SK.AGER RAK. 



Rak. Considering the more complete collection from almost the same season (August 

 15th — 16th) in 1912, this series will thus chiefly serve to inform us of the fluctuations 

 and inegalities in different years, variations that may not, however, be expected to reach 

 the same extent in a summer-season, always poor in plankton, as at the times of the 

 great winter- and spring-maxima. 



Table 46. S. Skag. 6. 57° 56' N., 9° 40' E. 1. VIII. 1913. 



Depth 



Tempera- 

 ture ° C. 



o 



>> 



G 



"3 

 w 



>> 

 °5 



G 

 o> 



Q 



Paralia 

 sulcata 



Leptocylin- 

 drus danicus 



Rhizosolenia 



alata 



f. graeillima 



Diatoms 



total 

 numbers 



Gymnodinia 



total 



numbers 



.2 

 'c 



'•v 



o 



G ' 

 01 



o 



.2 

 -»a 



ca 



CD 



O 



Peridiniales 



total 



numbers 



Mesodinium 



Laboeae 



total 

 numbers 



S-S 



o -ä g 







15,38 



30.7 7 



22,65 







1 

 160 380 



80 



00 



KKI 



440 



00 



980 



1,380 



20 



10,99 



34,05 



2G,52 







20 40 







580 



000 



40 



680 



920 



40 



7,82 



34,90 



27,26 







4(1 



20 







20 



20 



140 



260 



CO 



7,62 



34,94 



27,31 



580 





700 



10(1 



70 



20 



200 



30 



100 



210 



103 



7,28 



34,97 



27,38 



780 





l 930 



l.l 







60 







100 



Under the warm and somewhat diluted surface-layer, there is a very uniform, salt 

 water of 7°,s — -7°,3 from about 30 m to the bottom, being markedly poorer in organisms 

 in its uppermost part, than the overlying surface-water. The Tripos-plankton is confined 

 to this latter, Paralia to the deeper layers. When comparing with the conditions of the 

 preceding year — observed a fortnight låter, see table 7, p. 10 — several differences are 

 evident. Firstly, diatoms were much more common all through in 1912, and so were the 

 Peridiniales, showing the notable feature of a strong increase for both beneath 20 m, 

 with up to 470 Ceratia per 1 in so great a depth as 60 m, this being obviouslv caused by 

 an under-current, rieh in plankton and less salt, though colder, than the water above it. 

 Such an import of plankton has not taken place in August 1913. On the other side, in- 

 ftisorians, principally Laboem, are much more frequent in this latter series. 



Table 47. S. Skag. 8. 58° 10' N., 9° 18' E. 2. VIII. 1913. 



,G 



CD 



Q 



Tempera- 

 ture ° C. 



O 

 O 



n 

 >. 



m 

 G 

 CD 



Q 



Paralia 

 sulcata 



Leptocylin- 

 drus danicus 



Rhizosolenia 



alata 

 f. gracillima 



Diatoms 



total 

 numbers 



Gymnodinia 



total 



numbers 



Glenodinia 



Ceratia 



Peridiniales 



total 



numbers 



Mesodinia 



Laboeae 



total 

 numbers 



Piotozoa 



total 

 numbers 







16,85 



30,50 



22,12 





220 



260 



730 



270 



880 



40 



1,610 



110 



2,120 



2,840 



20 



G,04 



34,38 



27,09 





60 



60 



1,680 



660 





3,040 



20 



1,660 



5,100 



40 



5,85 



34,05 



27,31 





160 



+ 260? 





840 



520 



260 





1 ,000 



60 



5G0 



960 



60 



0,38 



34,83 



27,40 



140 



90 





390 



4o 







80 



30 



110 



280 



100 



6,40 



35,01 



27,55 









70 



10 



20 





50 





10 



70 



200 



5,79 



35,07 



27,66 



60 







70 









10 







20 



400 



5,98 



35,10 



27,06 

















20 









G00 



5,98 



35,10 



27,66 



. 









20 







40 







20 



675 ' 



5,99 



35,10 



27,66 



300 







300 









20 







10 



This sample was taken August 14tli. 



