Aquatic Vegetation, Largemouth Bass and Water Quality Responses to Low-dose Fluridone Two Years Post Treatment

Whole-lake techniques are increasingly being used to selectively remove exotic plants, including Eurasian watermil-foil (Myriophyllum spicatum L.). Fluridone (1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone) , a systemic whole-lake herbicide, is selective for Eurasian watermilfoil w...

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Bibliographic Details
Published in:Journal of aquatic plant management 2005-07, Vol.43 (2), p.65-75
Main Authors: Bremigan, M, Hanson, S M, Soranno, P A, Cheruvelil, K S, Valley, R D
Format: Article
Language:English
Subjects:
Freshwater
Micropterus salmoides
Myriophyllum spicatum
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Summary:Whole-lake techniques are increasingly being used to selectively remove exotic plants, including Eurasian watermil-foil (Myriophyllum spicatum L.). Fluridone (1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone) , a systemic whole-lake herbicide, is selective for Eurasian watermilfoil within a narrow low concentration range. Because fluridone applications have the potential for large effects on plant assemblages and lake food webs, they should be evaluated at the whole-lake scale. We examined effects of low-dose (5 to 8 ppb) fluridone applications by comparing submersed plant assemblages, water quality and largemouth bass (Micropterus salmoides growth rates and diets between three reference lakes and three treatment lakes one- and two-years post treatment. In the treatment lakes, fluridone reduced Eurasian watermilfoil cover without reducing native plant cover, although the duration of Eurasian watermilfoil reduction varied among treatment lakes. Large pre-treatment differences among lakes in plant cover persisted, reflecting morphometric differences. We detected no treatment effects on water quality, and estimated the probability of treatment converting a lake to eutrophic conditions as being 200 mm total length did not change in treatment lakes and we detected few treatment effects on their diet. However, in two treatment lakes, growth of smaller largemouth bass increased modestly following treatment. Overall, the extent of effects of low-dose fluridone treatment differed among lakes, apparently reflecting differences in initial conditions that, in part, were driven by lake morphometry. Therefore, future evaluations should include more lakes, chosen to represent a range of morphometry, allowing extrapolation of findings to regions containing many diverse lakes.
ISSN:0146-6623