36 



David L. Penrose, David R. Lenat, K. W. Eagleson 



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1977 



1978 1979 



MONTH/YEAR 



Fig. 3. Average number of organisms per sample, French Broad River, June 

 1977-July 1979. 



effect on benthic fauna in the French Broad River. 



A sharp increase in the number of benthic organisms was asso- 

 ciated with low discharge rates, especially in the fall of 1978 (Fig. 1). 

 However, a decline in the number of organisms at station 2 was 

 observed in October 1978. This decline may have been caused by activi- 

 ties in the watershed of the North Fork. We learned that a fish kill 

 occurred just above station 2 in late July 1978. According to the Ashe- 

 ville Citizen (1978), 1,200 fish (mostly brown trout) were killed in John- 

 nies Creek, Tucker Creek, and parts of the North Fork of the French 

 Broad. The suspected cause of the kill was a pesticide in the Johnnies 

 Creek watershed. Passage of a pesticide (as a "slug dose") through sta- 

 tion 2 could have caused the fluctuations in density observed there. Plec- 

 optera, which are highly sensitive to a variety of pesticides (Jensen and 

 Gaufin 1964; Courtemanch and Gibbs 1977; Eidt 1975), were not col- 

 lected from this area in September 1978. 



Taxa Richness: River Stations. — Only 1978 and 1979 data are pres- 

 ented in Figure 4, because pre- 1978 collections were identified mostly to 

 genus. Several trends may be observed. Taxa richness at station 1 was 

 remarkably constant, particularly for the last six sample periods. This 

 pattern suggests that total taxa richness in this area is independent of 



