9504 - Laserfiche WebLink

Home Browse Search

Chironomids were the dominant taxa in the bulrush and river- communities benthos (Figure 27). In the open water community `, invertebrates other than Chironomids (including Gastropoda, Nematoda, Odonata, Hemiptera, Culicidae, Ephemeroptera, and- Coleoptera), occurred in greater numbers and in the backwater .community-the density of chironomids and other invertebrates were equal. Chironomids dominate the benthic environment having equal or greater-numbers-than all other taxa combined. Overall, bulrush and open water communities had-the highest numbers of invertebrates L'1. -This was true whether considering just the water column or the water column combined with benthos to 2 cm in-depth. Comparatively, the backwater and river communities are relatively barren of water column invertebrates. The-open water station M8 had by far the .highest mean densities of invertebrates L"1 for both zooplankton-and benthos (Figure 28). The season mean for water column invertebrates at this station was 105 individuals L'1 and 237 individuals L'l for benthos. -The bulrush station M7 also had high zooplankton .numbers at 83 individuals L'1 followed by open-water station M3 at 56 organisms: L'1. For-benthic samples the-open water station M19 and the-bulrush station M2 had.65 and 54 individuals L'1 respectively. The variability in zooplankton between stations -and communities can be seen in Figure 28. For benthic samples, excluding M8,-the variability was in general. less extreme. However, among open water and bulrush communities, no benthic ~'' organisms were found in one station of each type for-the entire sample period. 47