Novel approaches in macroinvertebrate biomonitoring
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The increasing popularity of benthic macroinvertebrate use for biological monitoring and assessment of lotic systems calls for new applications for regions with a lesser known fauna and an overall better understanding of how community measures are influenced by seasonal variability. Two separate studies are presented to address aspects of biological monitoring that are seldom studied. The first study focused on evaluation of Grass Riparian Filter Strip effectiveness in north central Missouri. Streams within conservation areas and unprotected reaches were sampled to identify metrics that could distinguish between undesired and best attainable conditions. These metrics were used to construct two assessment tools, a Benthic Index of Biotic Integrity (B-IBI) and a novel technique we call a Least Desired Index (LDI). LDI works in a reciprocal fashion to B-IBI in that the lowest scoring criteria of the metrics are set by anti-reference stream conditions, or conditions that represent an undesirable quality. B-IBIs were developed from the conservation stream samples and the LDI was developed from the unprotected stream reaches. Two test sites with established GRFS were sampled and assessed with the B-IBI and the LDI. B-IBI determined that the GRFS sites showed moderate improvements where the LDI showed that the GRFS sites made no improvements. The LDI was considered to be a more realistic assessment considering that the GRFS at the test sites had only been established for 2 years and the reference streams used to construct the B-IBI were most likely impaired. The second study utilized a state designated reference stream as a case study for temporally profiling the community structure. Samples of benthic macroinvertebrates and water quality were taken approximately monthly to fulfill four objectives. The first objective was to determine if a temporal profile of the community might better reveal members of the community that are rare and transient. The second objective was to consider the maturity of each individual in weighting abundances and how these might affect the interpretation of the community structure. The third objective examined annual variability of 120 metrics. Multiple regressions with physico-chemico-temporal variables were created to see if these metrics could be predicted for samples taken during the following year. The last objective was to construct a River Invertebrate Prediction and Classification System (RIVPACS) model that classified seasons based on the biota and to use this model to predict and compare the community composition of samples taken during the following year. Rare and two types of transient taxa were recognized. Rare taxa were considered to be residents of the community, but infrequently encountered. Transient type I taxa were considered adventitious, and transient type II were short lived. Maturity weighted abundances showed significant changes in community measures and were found to be useful in aspects of other analyses. Few metrics exhibited low variation over the annual period, and fewer were predictable, indicating that seasonal variation can have a significant impact on measurements used in biological monitoring. The RIVPACS model biologically classified three seasons. Overall, the model moderately predicted community structure, also highlighting that macroinvertebrate communities are difficult to consistently quantify. Lotic habitats are important resources but are dynamic systems exhibiting challenging perspectives with regard to monitoring and quality assessment.
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