Table 11. — Percentage of pretreatment number of 



aquatic invertebrates in samples for various streams 

 and substrates 1 week, 6 weeks, and 1 year after 

 treatment and in control streams. Lakes Superior and 

 Michigan, 1962-64 



streams could act as hatcheries or reserves; 

 and (3) upstream migrations could have 

 occurred, because chemical concentrations 

 were less in the lower reaches of streams 

 and many organisms were probably affected 

 little if at all in these areas. Downstream 

 drift (Waters, 1961) may have been another 

 factor that influenced reestablishment in this 

 study; streams were not treated from their 

 sources, so the unaffected populations of 

 invertebrates were available from the head- 

 waters of most treated streams. 



In the three stations that were sampled 1 

 year after treatment, all showed complete 

 recovery in total number of organisms, and 

 all major groups present before treatment 

 were well represented. Thus, aquatic inverte- 

 brates, although affected moderately by the 

 selective lamprey larvicides, usually recov- 

 ered substantially in 6 weeks and fully in 1 

 year. 



ACKNOWLEDGMENTS 



Wesley J. Ebel initiated the study, and 

 Albert W. Bowers drew the figures. 



LITERATURE CITED 



ANDERSON, RICHARD O. 



1959. A modified flotation technique for 

 sorting bottom fauna samples. Limnol. 

 Oceanogr. 4: ZZi-ZZb. 

 APPLEGATE, VERNON C, JOHN H. HOWELL, 

 JAMES W. MOFFETT, B. G. H. JOHNSON, and 

 MANNING A. SMITH. 

 1961. Use of 3-trifluoromethyl-4-nitro- 

 phenol as a selective sea lamprey 

 larvicide. Great Lakes Fish. Comnn., 

 Tech. Rep. 1, 35 pp. 

 FREY, PAUL J. 



1961. Effects of DDT spray on stream 

 bottom organisms in two mountain 

 streams in Georgia. U.S. Fish Wildl. 

 Serv., Spec. Sci. Rep. Fish. 392, ii 11 

 pp. 

 HOWELL, JOHN H., EVERETT L. KING, JR., 

 ALLEN J. SMITH, and EEE H. HANSON. 

 1964. Synergism of 5,Z'-dichloro-4'-nitro- 

 salicylanilide and 3-trifluoromethyl-4- 

 nitrophenol in a selective lamprey larvi- 

 cide. Great Lakes Fish. Comm., Tech. 

 Rep. 8, Z\ pp. 

 MOFFETT, JAMES W. 



1936. A quantitative study of the bottom 

 fauna in some Utah streams variously 

 affected by erosion. Bull. Univ. Utah 

 26(9): 33 pp. 

 PENNAK, ROBERT W. 



1953. Fresh-water invertebrates of the 

 United States. The Ronald Press Com- 

 pany, New York, 769 pp. 

 SANDERSON, MILTON W. 



1938. A monographic revision of the North 

 American species of Stenelmis (Dryop- 

 idae: Coleoptera). Univ. Kansas, Sci. 

 Bull. 25: 635-717. 

 SMITH, ALLEN J. 



1967. The effect of the lamprey larvicide, 

 3-trifluoromethyl-4-nitrophenol, on se- 

 lected aquatic invertebrates. Trans. 

 Amer. Fish. Soc. 96: 410-413. 



WATERS, THOMAS F. 



1961. Standing crop and drift of stream 

 bottom organisms. Ecology 42: 532- 

 537. 

 WATERS, THOMAS F., and ROBERT J. 

 KNAPP. 

 1961. An improved stream bottom fauna 

 sampler. Trans. Amer. Fish. Soc. 90: 

 225-226. 

 ZIMMERMAN, JEROME W. 



1968. Water quality of streams tributary 

 to Lakes Superior and Michigan. U.S. 

 Fish Wildl, Serv., Spec. Sci. Rep. Fish. 

 559, iii + 41 pp. 



MS. #1761 



13 



