Comparing indicator variability across ecosystem components

D.H. Anderson. Ecosystem Restoration Department, South Florida Water Management District, West Palm Beach, Florida 33406

Variability is consistently identified as an important criterion for selecting indicators of environmental change; however, most studies compare variability across metrics for a single group of organisms (e.g., fish, invertebrates, periphyton) and not across different ecosystem components. The success of the Kissimmee River restoration is being evaluated with 42 expectations for major ecosystem components, including abiotic features (hydrology, water quality) and biotic communities (plants, invertebrates, fish and birds). Baseline data from the channelized river for 60 metrics provide an opportunity to compare indicator variability across ecosystem components. Variability was estimated using the coefficient of variation (CV = standard deviation/mean). Baseline CVs ranged from 0.003 to 3.67 for all metrics with a median of 0.3. The range of CVs broadly overlapped for most components including hydrology (0.03-3.00), geomorphology (0.46-2.01), invertebrates (0.11-1.42), fish (0.26-3.3), and birds (0.11-3.67). Water quality (0.09-0.86) and plants (0.003-0.47) had narrower ranges. While these results are for a small subset of possible metrics and for a single river, they demonstrate that biological data are not necessarily more variable than physical-chemical data and that fairly low variability can be achieved for many different ecosystem components.