430 Elimination of A Igce in Locks and Ponds. [Sess. 



Since this paper was read to the Society in March last, 

 and noticed in the local newspapers, several letters have 

 been received from estate factors, civil engineers, and others, 

 inquiring as to the effect of sulphate of copper upon 

 flowering aquatics. The Canadian pond weed (Anacharis 

 alsinastrum or Modea canadensis) is specially mentioned by 

 some, and also that trout and other fish which it is desirable 

 to preserve are present in the same lochs with that weed. 

 The ubiquitous Anacharis has caused considerable trouble 

 and loss at Lochleven, where in 1903 the loch was literally 

 crammed with it, and the fishing in consequence was almost 

 an entire failure. When the plant began to putrefy and 

 decay, the water was of the consistence of pea-soup, and 

 many fish were killed off, dead trout from IJ to 2 lb. 

 weight being picked up in numbers along the shores of the 

 loch. Last year (1911) the conditions were not much 

 better, although during the past summer the loch has been 

 singularly free of weed. At present the only means of 

 dealing with this pestilent plant is the tedious and unsatis- 

 factory one of raking it out. As the question of the 

 application of copper sulphate to it and other flowering 

 aquatics and semi - aquatics was a very difficult one, I 

 referred some of my correspondents to the authorities at 

 Kew. At the same time, I submitted the matter to 

 Professor West, who very kindly replied as follows : " I 

 should hesitate to apply the copper treatment to any of 

 the larger macrophytes. The quantity required would, so 

 far as I can see, entirely destroy the fish. The minute 

 quantities which kill the Algse have no effect whatever on 

 the larger plants — unless it be to make them grow better ! 

 A good deal of experiment is needed in this direction." 



Amongst the communications received from Estate Offices 

 was one from the Bridge of Allan, stating that on the 

 Airthrey Castle estate there was a loch of 25 acres in extent 

 which was crowded with vegetation, and inquiring whether 

 •copper sulphate might be applied, and in what proportion. 

 Professor West was again consulted, and specimens of the 

 floating Alga were sent to him. This was pronounced to 

 be Glceotrichia echimdata, one of the Blue - green family. 

 Of this Alga "millions of floating particles" were reported 



