37 



VI. Dead Weed. 



It Iias already beeu mentioned (p. 6) that the cast-off leaves of the Zostera 

 aud the slioots loosened in various ways Hoat about in the water in larger or 

 smaller clusters, until they are either thrown up on the beach or sink to the 

 bottom. The deposition occurs quite by degrees and the sinkiug masses are often 

 carried a long distance by the cnrrents before they settle. A necessary condition 

 for the setthng of the masses of dead weed is, that they should be carried out 

 into depths and piaces where there are no currents. Tiie dead weed may then 

 be collected into enormous quantities so that it covers the sea-bottom for con- 

 siderable distances with a thick laj'er of entaugled masses. It is owing to the 

 Zostera's power of resistance to putrefaction that the accumulations eau become so 

 enormous; it is quite diflerent with the sea-weeds (algæ) which very quickly 

 crumble and decay. The dead weed is of no inconsiderable importance to our 

 waters, as it impedes fisliing with seines at several piaces and as the bottom, 

 where the dead weed forms a thick cover, is not a good place for the animals 

 Jiving in the upper lavers and on the surface of the sea-bottom, many of which 

 are of importance as food for our food-fishes, especially flat-fisli. 



If one consults a chart showing the depths in our marine waters, one 

 might almost calculate where there are accumulations of dead weed. It must be 

 sought for in the deeper bays and at the bottom of the channels 

 through our waters, especially in the deep parts of the channels. The 

 dead weed in contrast to the living Zostera may occur in fairly great and very 

 varying depths. 



In the observation material at the end of this paper, the data of the 

 occurrence of the dead weed whicli I have been able to procure are stated; but 

 they only give an iudication of its distribution in our waters. I think, however, 

 that they indicate where there is much dead weed. Referring for details to the 

 observations themselves, I may hare, as in stating the distribution of the living 

 Zostera, give a short survey of the most important piaces where it occurs. 



1. AVest coast of Jutland. So far as I know, there are nowhere large 

 accumulations of dead weed off tlie west coast of Jutland, aud the conditions for 

 these — plentiful growth of the Zostera and little motion on the sea-bottom — are 

 also lacking, unless porliaps at Esbjerg. 



