| Resource Inventory: Hudson River Submerged Aquatic Vegetation | |
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Mapping was carried out using procedures consistent with NOAA guidelines published in chapter 4 of "Guidelines for Monitoring Submerged Land Using Aerial Photography". High quality, true color aerial photographs were aquired during periods of low tide from about mid-July through August in 1995 for Phase I and 1997 for Phase II. Photographs were acquired to provide stereoscopic coverage at 1:14,400 scale. The classification focuses on identification and mapping of Vallisneria americana (Va) and Trapa natans (Tn). Although the predominant species in the Va category is V. americana, mixed species of plants growing submerged in the Hudson River and rooted in the riverbed may also be included. The mapping of Trapa natans, a floating leaved, rooted aquatic plant, was seen useful as it is widely distributed in the river, the extent of which is also unknown. In the interpretation and mapping process using aerial photographs, the image analyst developed characteristic signatures for identification and interpretation of vegetation dealing primarily with colors and spatial configuration. Ground-truthing was conducted with actual sampling of SAV beds to describe abundance, biomass, and species composition. During ground-truthing of polygon beds north of Albany, observations were made of frequent occurrences of very narrow linear beds of Vallisneria located adjacent to the shoreline (photo to the right). These features generally appeared to be in the two-to-three meter width size, and because they did not provide a signature were not visible on the color aerial photographs. In some instances, the plants were overshadowed by tree cover along the shoreline. These were subsequently mapped from the ground using techniques combining grab sampling and GPS and labeled linear features. True color aerial photographs of the entire Hudson River reach were acquired in the summer of 2002 in order to develop updated inventory data on SAV beds and to conduct trend analysis studies.
Additional functional assessment work is being done through multi-year monitoring and ecological studies of submerged aquatic vegetation on a set of references sites. This is providing insights into how these plants provide food, oxygen and critical habitat for fish and invertebrates. A synthesis of findings is expected to be available early in 2005. PowerPoint slides about the SAV project Fact sheet about the SAV project Contacts Principal Investigator: Eugenia Barnaba, (607) 255-0800 (emb6@cornell.edu) Image Analyst: Susan Hoskins (607) 255-6529 (sbh1@cornell.edu) HRNEER Research Coordinator: Chuck Nieder (914) 758-7013 Partners Department of Crop and Soil SciencesInstitute of Ecosystem Studies New York Sea Grant New York State Department of Environmental Conservation / Hudson River National Estuarine Research Reserve NYSDEC Hudson River Estuary Program NOAA Coastal Services Center Coastal Change Analysis Program Funding Sources
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Remote sensing is being used to document the spatial distribution of submerged aquatic vegetation (SAV) beds in the Hudson River. SAV has been recognized as an important component of a wide variety of ecosystems due to its contribution to primary productivity and its importance as habitat for fishes. Mapping of SAV has been undertaken through two projects. Phase I, funded by the National Oceanic and Atmospheric Administration (NOAA) Coastwatch Change (C-Cap) program, covers the area from Hyde Park to Castleton (about a 45 mile stretch). The larger phase II study, included the area from the Troy Dam to Castleton and Bolles Island to Hastings on Hudson (approximately 80 miles), and was funded by the New York State Estuary Program.
North of Albany, narrow linear features of Vallisneria
Features located adjacent to the cribbed shoreline
Typically, features are less than three meters wide and often less than two meters in depth.
