The Effects of Fluometuron on a Salt Marsh Ecosystem1
- J. D. Allen and
- D. E. Davis2
A salt march on Sapelo Island, Georgia, dominated by a mono-specific stand of spartina (Spartina alterniflora Loisel) was treated with fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea]. Treatments were: spraying once each year with 90,000 ppm; spraying 30 times (twice each day for 5 consecutive days in 3 consecutive months) with 1,000, 100, 10, 1, or 0 ppm; or flooding 30 times (frequency as described above) with 100 or 0 ppm. One-half of each plot was re-treated in the same manner the second year while the other half was left untreated. Effects on spartina, periwinkle snails (Littorina irrorata Say), and horse mussels (Gukensia demissus Dillwyn) were measured 4 mo after the first treatment. Only spraying once with 90,000 ppm fluometuron or 30 times with 1,000 ppm significantly reduced fresh weight, dry weight, or number of shoots of spartina and re-treatment the second year at the same rates did not increase the effect. The spartina on the plots treated the first year but not retreated the second year recovered completely. One year after the last of 30 sprayings with 1,000 ppm or 1 spraying with 90,000 ppm, there were significant levels of fluometuron residue in the spartina harvested from these plots.
Flooding 30 times with 100 ppm of fluometuron did not significantly decrease the total fresh or dry weight of spartina, but did cause visible injury symptoms and did decrease the number of shoots. Flooding 30 times with 100 ppm was nearly as toxic as spraying 30 times with 1,000 ppm. Neither flooding nor spraying adversely affected the number or weight of snails. The snails were not confined to the plots but fluometuron residues in them reflected the treatment rates so migration into or out of plots must have been minimal. Flooding with 100 ppm fluometuron did not adversely affect the mussels.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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