120 Roosevelt JJ'ild Life Bulletin 



Lakes Microcystis dominates, in Stahahe Lake Anabaena, while in 

 Cedar Lake the coloration of the water is caused by Coelosphaerium. 

 Queensboro Lake, which was built at the same time, and Barnes Lake, 

 just outside the Park boundaries, have not developed blooms of 

 blue-green algae, although in the case of Queensboro Lake there is 

 a large growth of Eudorinu i PI. 6, Fig. 7; and Syniira nvella (PL 5, 

 Figs. 2-3;. 



When these recently built artihcial lakes that produce blooms are 

 compared with the other artificial lakes of the region Qlap 3) 

 it will be noted that only one old artificially enlarged lake has a 

 suflicient development of blue-green algae to come in the bloom class. 

 In contrast to the conditions found in Popolopen Pond the flora of 

 Mine, Cranberry, Echo, and Little Dam Lakes i^all old artificial 

 lakes), or Summit and Forest Lakes (old artificially enlarged lakes j, 

 is not characterized by a conspicuous development of blue-green 

 algae. These lakes all lie in the belt of Precambrian rocks shown 

 in Map 2. Tw^o of these enlarged artificial lakes ('Summit and 

 Forest; are of the Caledonian t}"pe; the other shallow artificial lakes 

 do not have a sufficient proportion of desmids to be called Cale- 

 donian associations. It does not seem unreasonable to assume that 

 these lakes have reached a fair state of biological equiUbriimi, or 

 that they have reached their normal lacustrine flora. If this is 

 true it does not seem improbable that the flora of the new artificial 

 lakes of the Park, which at present are producing large numbers of 

 blue-green algae, will gradually undergo changes in nature, and when 

 this flora arrives at a fairly constant state, making all due allow- 

 ance for the fact that the plankton of a lake varies from year to 

 year, it will be similar to that of other old artificial lakes of the 

 region. These new artificial lakes all lie in a region (Map 3; 

 where the stable lakes have the t\'pical high desmid content and low 

 blue-green development of the Caledonian plankton formation, and 

 in all probabilit}- some of them wiU eventually arrive at a condition 

 resembling Summit or Forest Lakes. 



The cause of an intensive development of blue-green algae in 

 newly formed reser\"oirs is a complicated problem involving a nimi- 

 ber of unsolved factors. Little Long Pond is a true desmi-d lake 

 and one with very few blue-green algae. It might be a natural 

 inference that if the water from this lake were collected in a new 

 lake the plankton organisms in the new and the old lakes would be 

 practically the same, since the old lake is continually introducing its 

 algae into the new lake. In actual practice this has not been the 

 result. Kanahwauke Lake was formed by damming the valley 

 below Little Long Pond and impounding the water of its outlet. 

 The plankton of Kanahwauke consists ver\- largely of Microcystis 

 rPl. 3, Figs. 11-13) and Phaeoflagellates (PI. 5), with only occa- 

 sional desmids. The source of the waters in the tw^o lakes is the 

 same and so the explanation must be sought in the changes taking 

 place in the nature of the water in Kanahwauke after its entrance 

 into the lake. In the building of Kanahwauke Lake no attem^Dt 



