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Bulrush Community -water column invertebrates <br />Four stations, M2, M7, M14, and M19 were originally selected <br />to represent-the bulrush community at the Moab Slough.. Station- <br />-. M19 was established after the first sampling period an M14 <br />abandon to add a third bulrush sample site. As seen from <br />previous data the. bulrush community is the most productive <br />wetland community with regard to mean .number of invertebrates L' <br />'~. Taxonomic groups representing the zooplankton in the bulrush <br />community appear in Figure 31. <br />Cladocera were the most abundant organisms in the water <br />column, and their density was at its peak .during our 30 July <br />sample period at station M7 with 307 L"1. Station: M7 also had <br />the greatest .number of Cladocera on the two previous sample <br />periods of l July and 17 July., Relatively low numbers of <br />Cladocera were seen at the first sample period and during the <br />last two sample periods. -This was most likely due to Colorado <br />River flooding through-these sites. <br />Copepods abundance was .more consistent than Cladocera at all <br />stations throughout the sampling season. All: stations had <br />relatively similar. numbers of Copepods. The highest densities of <br />copepods occurred on 17 July with 43 L"1 at station M19. <br />Chironomids in-the water. column ranged from 0 L"1 (M7 on 16 <br />-July, M2 -and M19 on 18 October) to 1.9 ,L"1 (M7 on 30 July) at <br />bulrush stations. through the six sample periods. All stations <br />had. similar numbers of Chironomids over the-sample period. <br />-Other invertebrates were rarely-found in.our-sample. All <br />.occurred in densities below 0.16 individuals L"1 (not apparent on <br />,graph due to scale) except-.for station M2 on 30 July. At this <br />station the colonial protozoan Volvox sp. was encountered-and <br />.their numbers greatly inflated-.the count. <br />Bulrush Community - benthos <br />The bulrush stands had the highest .densities of chironomid <br />larvae of the communities sampled yet ..densities-were-more <br />variable seasonally .and among stations than in other communities. <br />(Figure 32). Maximum numbers occurred on 13 August with 171 <br />Chironomids L"1 at station M19 and other invertebrates numbering <br />223 L'1 at station M2. No benthic invertebrates were found in <br />samples collected on the -first sample date, l7 June. Small <br />numbers of Chironomids and other invertebrates were.collected on <br />17 June. Low numbers of other. invertebrates besides Chironomids <br />-were collected at station M19 on the last sample period of 18 <br />October. <br />54 <br />