Evaluation of fixed precision sequential sampling plans for larval chironomidae (Diptera) using bootstrap simulation

Based on spatial distribution patterns of chironomid larvae in Lake Monroe and Lake Jessup in central Florida, fixed precision sequential sampling pla ns were developed from data sets of Glyptotendipes paripes Edwards in Lake Jessup using a modification of Green's method, in which precision was expre ssed in terms of confidence limits of a predetermined half-width. These pla ns were verified and validated using dependent and independent data sets of G. paripes and Tanypodinae from both lakes using bootstrap simulation. Sim ulation results revealed that actual precision levels were heavily dependen t on the degree of larval aggregation, as depicted by k Value of the negati ve binomial distribution For the highly aggregated populations of G. paripe s in Lake Jessup, actual precision levels were lower than those intended. C onversely, higher precision levels were obtained for Tanypodinae, which wer e much less aggregated in these lakes. Lake-wide increases in sample sizes would lead to weak improvement of estimation. The present sampling plans (1 65-180 samples per lake) resulted in an actual precision level of approxima te to 0.50 for G. paripes, demonstrating the need for further modification of the sampling plans. This study revealed that fixed precision sequential sampling plans were liberal for the highly aggregated chironomid larval pop ulations and conservative for the less aggregated populations.