107 



Ecological Notes on Certain White River Alg/E. 



Paul Weatherwax. 



During the .summer of 1913, while assisting in a sanitary survey* of tlie 

 West Forli of Wliite River, tlie writer toolv advantage of the opportunity to 

 malie a study of the alg;ie in the stream. Tlie work was begun at Martins- 

 ville, Ind.. near the close of June, and ended at Mt. Carmel, 111., about tlie 

 middle of September, more or less hurried investigations being made along 

 the river near several of the larger towns. 



( )nly such forms were considered as were present in quantities suffici- 

 ent to be conspicuous to the unaided eye, no attempt being made to secure 

 specimens by filtration. The striking condition was the general scarcity 

 of alga?, especially along the lower part of the river. 



For four or five miles in the neighboi-hood of Martinsville the shallow 

 parts of the river were choked with a growth of Chidophoni (/litmcrata Kg. 

 and Hiidrodictijon ntviculaium Roth. ; and large masses composed of spe- 

 cies of Oscillatoria, Desmids, and Diatoms were continually floating down 

 the river. This material had evidently been broken loose from where it had 

 grown further up the river or some of its tributaries, for it did not continue 

 in a growing condition but eventually broke up and disappeared. The 

 Cladophora gradually became less noticeable in the deeper water a few 

 miles below Martinsville and was afterwards seen only occasionally and 

 in small quantities. The Hydrodictyon was iai well-defined locations in 

 water that was comparatively quiet, and, although it was rapidly reproduc- 

 ing, and the young nets were seen floating even far below Spencer, it appar- 

 ently did not find suitable conditions for growth far below Martinsville. 

 Spirogyra, Mesocarpus, and Zygnema were found in small quantities in a 

 few places, but they were not fruiting and usually showed signs of disinte- 

 gration. Numerous species of Diatoms were present in the shallower 

 places all along the river. 



*This survey was conducted by the Indiana State Board of Health Water Laboratory. To 

 State Water Chemist, Jay A. Craven, I am much indebted for some of the data and otlicr informa- 

 tion that have led to the publication of this paper. 



