Spatial distribution of chironomid larvae (Diptera: Chironomidae) in two Central Florida Lakes

Spatial distribution of larval Chironomidae was investigated in 2 lakes, Jessup and Monroe, in central Florida. Each lake was divided into 6 sections and benthic samples were seasonally collected from each section from October 1995 to February 1997. Among >30 species of chironomids collected, Glyptotendipes paripes (Edward) was predominant in Lake Jessup. In Lake Monroe, G. paripes and Tanypodinae were codominant, with Chironomus crassicaudatus Malloch being abundant only in the summer. Spatial distribution of dominant chironomid species was analyzed by fitting to the negative binomial distribution, Iwao's patchiness regression, and Taylor's power law. The negative binomial gave variable fits with the chi-square test and with the second moment statistic. Four out of 6 data sets of G. paripes in Lake Monroe fitted the negative binomial distribution based on a chi-square test, whereas in Lake Jessup no data set fitted to this analysis. In contrast, using the second moment statistic, more data sets (4 out of 6) in Lake Jessup fitted to the negative binomial than in Lake Monroe (1 out of 6). Fitness of the negative binomial was good for Tanypodinae in Lake Monroe. The Iwao's regression statistically fitted 8 out of 12 data sets of G. paripes; however, the wide range of beta values (3.12-15.96) suggested this method to be inappropriate for our data. All data sets of G. paripes statistically fitted Taylor's power law with aggregation index, b, ranging from 1.498 to 2.162. Homogeneity of Taylor's regression for G. paripes over sampling seasons was revealed in both lakes. Overall, Taylor's power law was a better descriptor for aggregated populations of chironomid larvae in these 2 lakes and provided a basis for developing sequential sampling plans.