Aquatic macroinvertebrate diversity and water quality of urban lakes

Macroinvertebrate species diversity and community composition are important themes in aquatic ecology, and are often used to evaluate environmental stress resulting from a variety of anthropogenic disturbances. On the Southern High Plains of Texas, urban areas have incorporated lakes into their stormwater and surface-water management systems. Eight urban lakes were selected to include a range of physical and biological features (i.e., lake size, relative potential for nonpoint source pollution, and presence of aquatic vegetation) representative of urban lakes in Lubbock, Texas. These lakes were categorized into three a priori groups based on the above characteristics. I evaluated 16 physicochemical attributes on a monthly basis, from February 1993 to April 1994, and found that 12 of the attributes contributed significantly to differences among groups of lakes during the study.

Macroinvertebrate community composition was sampled on six different dates in each lake to capture seasonal patterns in species diversity. No significant differences in species diversity (Fisher's log series a) existed among groups of lakes in the summer or for the combined seasons data, although significant differences did occur in the spring and fall. Groups of lakes that were signficantly different represent the extremes in habitat complexity and invertebrate community composition. Community composition of group 1 and 3 lakes were dominated by three to four families of invertebrates, whereas in group 2 lakes, over 60% of species abundance was attributed to one species.

Mantel's nonparametric test found a significant association between matrices based on water quality similarities and macroinvertebrate similarities during the fall sampling period. Furthermore, stepwise multiple regression using invertebrate species abundances as the dependent variable and water quality characteristics as the independent variables found significant relationships between corixid, notonectid, chironomid, and cladoceran abundances and salinity, total phosphorus, dissolved oxygen, total organic carbon, and ammonia. These attributes accounted for 33-76% of the variation observed in the abundances of these species. Of the water quality characteristics found to be significant predictors of species abundances, salinity, ammonia, and total organic carbon were correlated significantly to areal extent of multiple family housing and commercial land-use surrounding each lake. These results suggest that land-use may indirectly influence macroinvertebrate community composition of urban lakes.