||Effects of Drilling Fluids on 'Thalassia testudinum' and Its Epiphytic Algae.
Price, W. A. ;
Macauley, J. M. ;
Clark, J. R. ;
||Environmental Research Lab., Gulf Breeze, FL. ;University of West Florida, Pensacola. Dept. of Biology.
Drilling fluids ;
Sea grasses ;
Offshore drilling ;
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A flow-through microcosm system was developed to assess the potential influence of drilling fluids on Thalassia testudinum and its epiphytic algae. Two treatments (drilling fluid and a montmorillonite clay) and a control were used for seven tests: two 10-day, 200 microliter/l exposures; two 10-day, 1000 microliter/l; and three six-week, 190 microliter/l. Six-week exposure to drilling fluid reduced epiphyte biomass (measured as ash free dry weight/sq cm), but surviving algae did not differ (measured as chlorophyll a/g epiphyte ash free dry weight) from controls. Thalassia productivity (carbon uptake and growth rate) was reduced by 10-day exposure to drilling fluid concentrations of 200 microliter/l and 1000 microliter/l. Thalassia productivity was reduced by drilling fluid exposure in summer and fall but not in spring. The variation in response is attributed to seasonal changes in Thalassia allotment and storage of carbohydrates. The effect of montmorillonite clay exposure varied inconsistently among all tests for both Thalassia and epiphytes. (Copyright (c) Pergamon Journals Ltd. 1986.)