Impervious Surface, Summer Dissolved Oxygen, and Fish Distribution in Chesapeake Bay Subestuaries: Linking Watershed Development, Habitat Conditions, and Fisheries Management

Abstract

We estimated target and limit impervious surface reference points (ISRPs) based on Chesapeake Bay dissolved oxygen (DO) criteria, and we examined associations and relationships among the percentage of watershed in impervious surface (IS), summer DO, and the presence of indicator species (blue crab Callinectes sapidus, white perch Morone americana, striped bass M. saxatilis, and spot Leiostomus xanthurus) in bottom waters of nine brackish subestuaries of Chesapeake Bay. Ideally, a target ISRP represented a level of development that maintained mean bottom DO at 5 mg/L or greater, while an ISRP threshold represented development that degraded mean bottom DO to less than 3 mg/L. The proportion of bottom trawls containing each indicator species rapidly declined from about 0.40 to 0.10 when DO fell below 3 mg/L, whereas the proportion remained at about 0.50 when DO was above 5 mg/L. The IS percentage had a significant negative influence on mean bottom DO and the odds that indicator species were present in midchannel bottom waters (0.8–7.0 m deep). Watersheds at or below a target IS of 5.5% (rural watershed) maintained mean bottom DO above 3 mg/L, but mean DO was only occasionally at or above 5 mg/L. Mean DO seldom exceeded 3 mg/L in watersheds with an IS value above 10% (suburban threshold). Comprehensive watershed management will be needed to offset significant degradation of bottom-water fish habitat in brackish subestuaries if rural lands are converted to suburban areas.

Received July 6, 2010; accepted March 23, 2011

ACKNOWLEDGMENTS

The Impervious Serfs thank C. Jordan, H. Rickabaugh, and K. Whiteford for their help. We greatly appreciate D. Sides providing land use estimates from Towson University. This study was supported by Federal Aid in Sport Fish Restoration funds.