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Remote Sensing for Coastal Management
Effects of Tidal Restriction in Marsh HabitatsStructures such as roads, rail beds, dikes, and tide gates restrict tidal flow in coastal areas–which can alter the landscape and negatively impact the biodiversity and function of salt marshes. Coastal managers can use hyperspectral remote sensing data to determine the effects of tide restriction on marsh habitat and help prepare for future restoration and preservation projects. The Project: Measuring Habitat Heterogeneity in Tide-Restricted and Tide-Open Areas in the New Jersey Meadowlands1Salt marshes are diverse habitats that serve as natural cleansers for land-based pollutants and a nursery ground for a variety of plants and animals. Tidal influence is an essential part of maintaining salt marsh vitality; however, flourishing coastal areas are often altered by man-made structures that alter the natural landscape and hydrologic flow. Alterations in spatial configuration and hydrologic changes of wetlands can influence the abundance and diversity of wildlife in these areas.
Scientists from the Meadowlands Environmental Research Institute and Rutgers University compared habitat heterogeneity in tide-restricted areas and tide-open areas using hyperspectral remote sensing. Forty-one hectare plots in tide-open and tide-restricted marsh areas were randomly selected to identify landscape metrics such as the number of patches, total edge of patches, patch richness, patch-shape complexity, and species diversity. Using hyperspectral imagery to assess marshland heterogeneityHyperspectral imagery from the Airborne Imaging Spectroradiometer for Applications (AISA) instrument was used to create a thematic map of marsh surface types in the New Jersey Meadowlands. AISA is a remote-sensing instrument capable of collecting a large number of spectral channels (up to 286) within a wide spectral range (430 to 900 nanometers). Hyperspectral sensors measure the intensity of reflected solar energy across a continuous span of wavelengths–from shortwave infrared light to visible light and visible near-infrared light. Image measurements are made at many narrow contiguous wavelength bands–resulting in a complete spectrum for each pixel. The ResultA significant difference in landscape heterogeneity was found between tide-open and tide-restricted marsh areas. Tide-open sites displayed a greater number of patch types and a more even distribution than tide-restricted sites. Results from this project revealed the potential for using hyperspectral imagery on its own to identify marsh features that are ecologically significant. For More Information
1Artigas, F.L., and Yang, J. 2004. "Hyperspectral Remote Sensing of Habitat Heterogeneity between Tide-Restricted and Tide-Open Areas in the New Jersey Meadowlands". Urban Habitats. Volume 2. Pages 112 to 129. |
