Emergy Analysis of Tidal Freshwater Marsh and Mudflat Sportfish Communities on Anacostia River, Washington, D.C

The ecological role of tidal freshwater marshes as important fish spawning and nursery habitat has been studied, although fish utilization of associated intertidal mudflats have not been as extensively investigated. Using the same sampling methodology, fish surveys of three separate areas of the Anacostia River in Washington, D.C. were conducted using a boat based electrofishing unit. The sportfish utilization of an area of expansive intertidal mudflats is compared to that of a restored emergent marsh and that of nearby mature emergent marsh. The annual production of sportfish biomass from each system was estimated and converted to emergy and emdollar equivalents. While the mudflat survey areas were dominated by bullhead catfishes (Ictaluridae), the restored and mature emergent marsh survey areas supported greater numbers of piscivorous fish from the families Moronidae and Centrarchidae. The fisheries emergy analysis provided for an interesting dilemma in that the mudflat system devoid of any emergent vegetation produced greater total annual sportfish biomass emergy than either the restored or mature marsh systems, due entirely to the contributions of catfish which are considered gamefish in D.C. While the restored and mature marsh systems both supported catfish, their sportfish communities were more balanced in terms of species, numbers and biomass. From an emergy perspective, the mudflat system provided more sportfishery emergy and economic emdollar potential than that of the two marsh systems.