Wednesday, May 20, 2009: 9:45 AM
The ravine tributary streams surrounding Grand Valley State Universities Allendale campus represent unique and understudied ecosystems, worthy of significant restoration efforts and of long-lasting protection. Conversion from agricultural land use prior to the 1960’s to impermeable surfaces and buildings has resulted in dramatic changes to surface runoff rates and volumes. Erosion and slope destabilization has generated a spectrum from severely impacted to relatively pristine ravines. Macroinvertebrate diversity was positively correlated to NH4; total abundance was negatively correlated to PO4 and chlorophyll-a concentration. Runoff intensity was positively correlated to PO4, NO3, SO4 and Fe concentrations and negatively correlated to diversity and richness. Nutrients were rapidly taken up by benthic algae as evidenced by declining nutrients, and increased algal pigment and organic matter concentration from up to down-stream. Biological uptake did not translate into increased macroinvertebrate abundance, likely because of the flashy discharge regime. Blacknose dace (Rhinichthys atratulus), a species known to prefer cold, clean water, was most abundant in the most pristine ravine stream sampled. We were successful establishing biological base-line conditions prior to the initiation of a storm-water abatement program and can use these benchmarks to gage the efficacy of restoration using physicochemical, population, community and ecosystem functional attributes.
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