Distribution of Submerged AquaticVegetation Beds of the Tidal Hudson River

Stuart E.G. Findlay
Institute of Ecosystem Studies

(with Elizabeth A. Blair and William C. Nieder, Hudson River National Estuarine Research Reserve, Annandale, NY 12504; Eugenia Barnaba and Susan Hoskins, Cornell Laboratory for Environmental Application of Remote Sensing, (CLEARS))

This project has been successful in attaining the two primary goals: (1) to use aerial photography to document the spatial distribution of submersed aquatic vegetation (SAV) beds in the mid-Hudson River and (2) to conduct ground-truthing with actual sampling of SAV beds to describe abundance, biomass and species composition. Dr. Findlay and his colleagues currently are mapping vegetated areas in the remainder of the tidal freshwater Hudson supported by NYS funds, which will include both a change analysis and examination of the relation between SAV abundance and tributaries, human disturbances and bathymetry. Products available to date include large-scale maps of SAV in the study reach, Hyde Park to Castleton.

Submerged rooted vegetation (SAV) has been recognized as an important component of a wide variety of aquatic ecosystems due to its contribution to primary productivity and its importance as habitat for fishes. Given the important contribution of SAV to a number of beneficial estuarine functions, the reductions in extent of this habitat in many regions has led to a variety of management actions intended to improve conditions for its growth. The demise and resurgence of SAV may be due to multiple causes but good information on abundance, distribution and ecological limitations on SAV are prerequisites for understanding and management of this resource.

In the tidal freshwater Hudson River, there are dense stands of SAV in many shallow areas, and distributions seem to be strongly light-limited. In the Hudson, SAV has been shown to be an important habitat and feeding area for young fishes and may contribute to oxygen budgets. Unfortunately, there have been no large-scale investigations of the present distribution and species composition of SAV in the Hudson. Present understanding is based on fairly site-specific studies or mapping of areas adjacent to sites of the Hudson River National Estuarine Research Reserve (HRNERR or Reserve). This project conducted large-scale SAV mapping for the reach from Norrie Point to Castleton,NY. A combination of aerial photography and field sampling is providing valuable information on existing beds and suggest areas of potential colonization based on bathymetry or restoration.