Abstract

Based on spatial distribution patterns of chironomid larvae in Lake Monroe and Lake Jessup in central Florida, fixed precision sequential sampling plans were developed from data sets of Glyptotendipes paripes Edwards in Lake Jessup using a modification of Creen's method, in which precision was expressed in terms of confidence limits of a predetermined half-width. These plans were verified and validated using dependent and independent data sets of G. paripes and Tanypodinae from both lakes using bootstrap simulation. Simulation results revealed that actual precision levels were heavily dependent on the degree of larval aggregation, as depicted by k value of the negative binomial distribution. For the highly aggregated populations of G. paripes in Lake Jessup, actual precision levels were lower than those intended. Conversely, higher precision levels were obtained for Tanypodinae, which were much less aggregated in these lakes. Lake-wide increases in sample sizes would lead to weak improvement of estimation. The present sampling plans (165-180 samples per lake) resulted in an actual precision level of ≍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 populations and conservative for the less aggregated populations.

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