Ecological studies of larval Glyptotendipes paripes (Chironomidae: Diptera) in selected central Florida lakes for creating an exploratory temporal and spatial model of nuisance populations

Ecological and physiological influences on the chironomid midge, Glyptotendipes paripes, were examined to develop a qualitative spatial and temporal computer model of larval distributions in central Florida lakes. Larval population distributions of G. paripes were examined over a two-year period in three central Florida lakes (Dora, Yale, and Wauburg) in relation to selected water and sediment physico-chemical properties. Lake bathymetry and sediment physical compositions were extensively mapped in each lake. Composition of midge larvae in the gut contents of fish in relation to the standing crop of midge larvae in Lakes Dora and Yale was studied. Development times for immature G. paripes were determined in the laboratory by rearing under a series of constant temperatures. These data were used to construct an exploratory spatio-temporal computer model of G. paripes larval distributions in central Florida lakes.; Canonical correspondence analysis indicated that the primary, significant influences on distributions of G. paripes larvae in the study lakes were water depth and the following physico-chemical sediment characteristics: dry weight, total organic carbon and presence of sand, muck or vegetation. While G. paripes larval distributions tended to be associated with shallower, sandy substrates in Lakes Dora and Wauburg, these larvae were distributed over/in muck bottom areas of Lake Yale. The development requirements of this species were calculated to be 716 degree-days above 9.0°C from egg to emergence. Gut content analysis indicated that bluegill (Lepomis macrochirus) were indiscriminate feeders on midge larvae in shallower portions of the lakes and larvae in deeper portions of the lakes perhaps were not within the grazing range of the fish. When validated against previously collected data from Lakes Jesup and Monroe, the computer model successfully estimated G. paripes larval distributions. The final model was effective at estimating larval distributions in Lakes Dora, Yale and Wauburg with the exception of the field data collected from Lakes Dora and Yale during the latter part of the field study. Further work is needed to determine and understand the environmental conditions that produced the unusual changes in G. paripes distributions noted in these lakes that resulted in model predictions deviating from field data. Theoretical manipulations of conditions within the model produced results that indicated the model to be useful in preliminary ecological studies by providing initial hypotheses on G. paripes larval population responses to selected environmental conditions studies.