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MARINE ALGAL VEGETATION 



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a. The Sea. South of Iceland the salinity varies but slightly, 

 with the exception of the coastal water itself. During the summer, 

 at any rate, the salinity of the coastal water must be considerably 

 lower on account of the great amount of fresh water brought down 

 by all the rivers of the south. On the other coasts and especially 

 those of N. and E. Iceland the salinity varies according to whether 

 the layers of water originate from currents which are deficient in 

 salt or from the Irminger current, and also with the amount of 

 fresh water streaming out from land. At station 106 (see above) the 

 inferior salinity is evidently due to cold water from the Greenland 

 current, and at station 73 it is probably due to fresh water. 





b. The Fjords. The salinity inside the fjords varies consider- 

 ably and the variation is dependent upon the amount of fresh water 

 which intermingles with the water in the fjord, partly in the form 

 of river water and partly in the form of precipitated moisture. The 

 lowest salinity in the fjords was 1.31 %o in Eskifjor5ur after rain. 

 Heavy rainfalls must be capable of causing such an inferior salinity 

 in other places also, especially in narrow fjords, but this will not 

 last long, and as the littoral algae can endure heavy showers during 

 low-tide, they will not suffer to any extent worth mentioning. 



In places where the salinity is as low as in Sey5isfjor5ur 

 (9.23 °/oo), where a rather large river disembogues, the algal vegeta- 

 tion occurs sparingly, although algae are found, especially green and 

 brown algae. At a place like Borgarnes, where the salinity is low 

 (18.9; 26.9) on account of fresh water from Hvita, the algal vegeta- 

 tion occurs more abundantly than at the very head of Sey5isfjor5ur. 

 by the river, but the inferior salinity excludes certain species, for 

 instance, Polysiphonia fastigiata, although Ascophyllum occurs abun- 

 dantly. Further out, where the sea is more saline, it is not absent. 



It is especially in the surface-water of the fjords that the sali- 

 nity varies so much. It is greater in the large open fjords, such as 

 Faxafloi, than in the small land-locked fjords, such as Hvalfjor5ur, 

 a circumstance which must certainly be due to river- water. The 

 figures given show also that the salinity of the surface-water of the 

 smaller fjords is less in the inner part than in the outer part. The 

 same difference seems to appear also between the deeper layers of 

 water of the inner and outer parts. 



As a rule, the salinity of the deeper layers is higher and more 

 stable, which must be beneficial to the vegetation in the depths. 



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