| Analysis of data from a line transect survey in an 800 acre reservoir indicated that 1500 triploid grass carp stocked for hydrilla control were not effective in preventing the spread of this species 16 months after stocking. Hydrilla occurrence increased 21% from September, 1995 to September, 1996. However, results from an exclosure study indicated that herbivory was an important factor in determining macrophyte abundance in one cove of the lake. Macrophyte biomass was found to be much higher in areas excluded from herbivory than in adjacent control sites.; Aquatic macrophyte sampling using a Ponar grab was compared to rake sampling. While there was variation between the two methods in measurement of macrophyte occurrence, both methods consistently recorded similar trends in overall coverage and in spatial and temporal variation of macrophyte occurrence. |
