122 Roosevelt Wild Life Bulletin 



was made to remove the soil or even the vegetation, the site being 

 flooded without preHminary preparation as soon as the dam was 

 completed. This undoubtedly makes the water of the lake much 

 richer in organic matter than that of Little Long Pond, and this 

 richness in organic matter, coupled with a higher content of inor- 

 ganic salts due to the leaching of tlie soil, accounts for the changes 

 in the nature of the water favoring the -development of blue-green 

 algae. In enlarging Carr Pond to form Stahahe Lake, and in 

 joining the tAvo Cedar Ponds to form Cedar Lake, there was no 

 especial preparation of the lake bed. In the case of both of these 

 lakes there were swampy tracts along the shore, and when the swamps 

 were flooded on the fillmg of the lake large floating bogs developed. 

 Nothing is known concerning the plankton flora before these lakes 

 were enlarged, although the residents of the region report that the 

 lakes did not bloom before they were enlarged. At the present time 

 they bloom profusely, an-d this blooming has no doubt been accel- 

 erated by the abundance of decaying vegetable matter on the bottoms 

 and shores of the lakes. 



Origin of the Plankton Flora In a New Lake. ]\Iany students 

 of the algal flora of artiticial waters, especially the students of the 

 biological problems involved in the building of artificial reservoirs, 

 proceed upon the assumption that the organisms which will appear 

 in these reservoirs all come from the immediate drainage basin and 

 that swampy areas are centers from which " seeding " of the reservoir 

 takes place. As has been shown above the plankton flora is a highly 

 specialized one and in general the organisms constituting the major 

 portion of the plankton communit}- are not found in the shore 

 regions. The source of many of the plankton algae of an artificial 

 lake is not the drainage into the lake but some neighboring body of 

 water that contains a true plankton flora. The migration of algae 

 from place to place is a passive phenomenon, and may be brought 

 about by the agency of air currents, insects, or birds. 



The scanty observations on the subject of algal migration are con- 

 cerned largely with the migration of nonplankton algae, and are 

 based upon speculation -rather than actual observation. Birds are 

 considered the main agency causing invasion of algae into new 

 regions by Wille ('97), Borge ('97) and Borgesen ('01). Their 

 observations dealing with the Faeroes are of particular interest since 

 the algae found in these islands must all have been carried there 

 since the glacial epoch. The facts that aquatic birds fly from one 

 body of water to another, and that algae might adhere to them, give 

 a sufficient explanation if the algae are not killed by dessication 

 during the journey. If spores are carried they are undoubtedly 

 able to withstand the journey successfully, as G. Schroder ('86) has 

 shown that resting spores of algae withstand dn,-ing for some years 

 and then germinate. B. Schroder ('02) has observ^ed that vegetative 

 cells of algae have a considerable resistence to drying, and it may 

 well be that the gelatinous envelope frequently surrounding plankton 

 algae prevents a too great loss of water. 



