A Comparison of Two Methods for Estimating the Status of Benthic Habitat Quality in the Virginia Chesapeake Bay

Abstract

Macrobenthic communities in Chesapeake Bay, USA, have been intensively monitored since 1985. In 1996, the monitoring was expanded to include summertime stratified random sampling to produce unbiased estimators of community metrics that could be used to assess system wide trends in benthic habitat quality. From 1996 to 1998, two index approaches to assessing benthic habitat quality were used in the Virginia portion of Chesapeake Bay. One method relied on grab samples for calculation of the benthic index of biotic integrity (BIBI) based on macrobenthic community composition data. The other method used sediment profile camera images for calculation of the organism–sediment index (OSI) from image-derived data. On an annual basis, the mean for each of the indices were similar from year to year, indicating that the properties or processes that regulate benthic habitat quality were likely similar from 1996 to 1998. There were significant differences in the correspondence of the macrofaunal-based and image-based indices to classify a particular station as having stressed or good habitat quality. While the overall relationship between the scoring of each index for a station was significantly positive (1.4 odds ratio), when the BIBI indicated poor conditions existed at a station, the OSI tended to indicate good habitat quality at the station. This pattern was consistent with the hypothesis that benthic habitat quality (measured by the OSI) would improve before biotic integrity (measured by the BIBI). A high BIBI with low OSI, representing the opposite hypothesis, would be unlikely and rarely occurred. The formulation of macrofaunal-based BIBI and image-based OSI emphasized different aspects of the benthos–habitat relationship. The BIBI was community structure-oriented with an emphasis on species identity and richness. The OSI was process-oriented in that the images recorded the end products of biological and physical processes that structure the benthos. Indices such as BIBI and OSI that integrate structural and functional aspects of benthos hold promise as measures of benthic habitat quality.

Department

Center for Coastal and Ocean Mapping

Publication Date

2-12-2003

Volume

285

Journal Title

Journal of Experimental Marine Biology and Ecology

Pages

371-381

Publisher Place

New York, NY, USA

Publisher

Elsevier

Digital Object Identifier (DOI)

10.1016/S0022-0981(02)00538-5

Document Type

Journal Article

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