Quantifying the habitat structure and spatial pattern of New Jersey (U.S.A.) salt marshes under different management regimes

Abstract

Mosquito control measures have resulted in majorstructural alterations of many coastal marshes, withrelatively unknown consequences to larger ecosystemfunctioning. Parallel grid ditching and open marshwater management (OMWM) techniques are purposefullydesigned to alter the hydrological regime and therelative availability and/or characteristics ofstanding water on the marsh surface. With the growingrecognition of the important influence that habitatstructure and the configuration of the marsh-edgeboundary has on nekton utilization of salt marshsystems, the impact of mosquito control managementtechniques on the availability and quality of saltmarsh habitat deserves increased scrutiny. Usingdigital image processing techniques, we completed adetailed mapping effort for a 1800 ha study area inTuckerton, New Jersey to provide a picture ofsubtidal and intertidal habitat availability. Spatialanalysis techniques were used to quantify the relativeamount of habitat types and spatial pattern of theland-water interface under different managementregimes: parallel grid-ditched, OMWM and an unalteredreference. The parallel grid-ditched site had a muchlower incidence of marsh ponds which serve asimportant low tide and over-wintering refuge forcertain species of fish. In comparison, the OMWM sitehad a much greater amount of ponded water habitats.The grid-ditched site had a higher density of marshsurface-to-tidal water interface resulting in a lowermedian distance between the marsh interior and theadjacent tidal channel network. This study serves tobenchmark the habitat structure and spatial pattern ofa highly functioning natural marsh for use as areference site in regional wetland creation orrestoration efforts.