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1994 Carolinian Province Statistical Summary

Environmental Quality of Estuaries of the Carolinian Province: 1994 Annual Statistical Summary
Hyland, J.L., T.J. Herrlinger, T.R. Snoots, A.H. Ringwood, R.F. Van Dolah, C.T. Hackney, G.A. Nelson, J.S. Rosen and S.A. Kokkinakis.

1996. NOAA Technical Memorandum NOS ORCA 97. NOAA/NOS Office of Ocean Resources Conservation and Assessment, Silver Spring, MD.

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A study was conducted in the Carolinian Province to identify the estuarine resources of this region and assess their condition based on a variety of synoptically measured indicators of environmental quality. The Carolinian Province, one of 12 coastal regions established under the nationwide Environmental Monitoring and Assessment Program (EMAP), extends from Cape Henry, Virginia through St. Lucie Inlet, Florida. Indicators used in this study included measures of: (1) general habitat condition (depth, physical properties of water, sediment grain-size and organic carbon content), (2) pollution exposure (sediment contaminants, sediment toxicity, low dissolved oxygen conditions), (3) biotic conditions (diversity and abundances of macroinfaunal and demersal species, pathologies in demersal biota), and (4) aesthetic quality (presence of anthropogenic debris, visible oil, noxious sediment odor, and water clarity). A stratified random sampling approach was incorporated to support probability-based estimates of the areal extent of degraded vs. undegraded resources.

Estuaries were stratified into three classes based on physical dimensions: large estuaries, small estuaries, and large tidal rivers. This classification scheme resulted in the identification of 200 estuaries with an overall estimated surface area of 11,622 km2. There were three large estuaries, three large tidal rivers, and 194 small estuaries. A total of 84 base stations and 13 supplemental stations were sampled from June 30 August 31, 1994. Base stations were randomly selected sites that formed the core of the probability-based monitoring design. By estuarine class, base stations included 20 in large estuaries, 47 in small estuaries, and 17 in large tidal rivers. By subregion, there were 46 stations in southern Virginia North Carolina, 20 in South Carolina Georgia, and 18 in Florida. Supplemental stations in suspected contaminated areas provided sites for field validation of additional ecological indicators developed during the study.

Over half (54%) of the surface area of these estuaries showed no major evidence of environmental degradation based on any of the measured biotic, exposure, or aesthetic indicators. Twenty percent of the province, represented by 17 stations, exhibited adverse biological conditions linked to significant pollution exposure (significant sediment toxicity, high sediment contamination in excess of reported bioeffect guidelines, or low dissolved oxygen concentrations in bottom waters). The majority (11) of these sites were in North Carolina. Most were characterized by degraded infaunal assemblages accompanied by high sediment contamination and/or significant sediment toxicity based on Microtox assays. Biotic indicators based on demersal species variables were not as effective as infaunal variables in discriminating between undegraded and degraded stations (classified on the basis of exposure indicators). Additional localized impacts not accounted for in the above estimate of degraded estuaries were detected at nonrandom supplemental sites near potential contaminant sources.

A strength of the EMAP-Estuaries probability-based sampling design is its ability to support unbiased estimates of ecological condition with known confidence. Further sampling in the Carolinian Province should improve the accuracy of these estimates and provide a basis for assessing how the overall quality of these estuaries is changing with time.

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