A benthic index of biological integrity for assessing habitat quality in estuaries of the southeastern USA

A benthic index of biotic integrity was developed for use in estuaries of t he southeastern USA (Cape Henry, VA; St. Lucie Inlet, FL) using a modificat ion of the method developed by Weisberg et al. (1997. An estuarine benthic index of biotic integrity (B-IBI) for Chesapeake Bay. Estuaries, 20 (1), 14 9-158). Data from non-degraded stations sampled in 1993 and 1994 were analy zed using classification analysis of species composition to define major ha bitat types relative to selected physical parameters. Various benthic metri cs were then tested on a larger 1994 data set for each major habitat to det ermine those that discriminated between nondegraded and degraded sites clas sified on the basis of dissolved oxygen, sediment chemistry, and sediment t oxicity results. Scoring criteria for each metric were developed based on t he distribution of values at non-degraded sites. Average scores from differ ent combinations of the most sensitive metrics were compared to derive the final index, which integrates the average scores of four metrics (number of taxa, abundance, dominance, and percent sensitive taxa). An independent da ta set representing sites sampled in 1993 and 1995 was used to validate the index. The final combined index correctly classified 93% of stations provi nce-wide in the developmental data set and 75% of stations in the validatio n data set. Comparison of the index results with those of individual benthi c measures and sediment bioassays from stations sampled in 1993 and 1995 sh owed that the index detected a higher percentage of samples where bioeffect s were expected (based on sediment chemistry) than did any of these other m easures individually. (C) 1999 Elsevier Science Ltd. All rights reserved.