Book
Distributional change in seagrass as an ecological indicator of estuarine health for Barnegat Bay - Little Egg Harbor, New Jersey
01 Jan 2010
Abstract
The Barnegat Bay-Little Egg Harbor (BB-LEH) estuarine system located along the eastern shoreline of Ocean County, New Jersey contains ~75% of New Jersey's known seagrass habitats (Lathrop et al, 2001). Eelgrass (Zostera marina) is the dominant species while widgeongrass (Ruppia maritima) is also common in lower salinity and shallow regions of the BB-LEH. Recent remote Sensing and in situ surveys collected prior to 2009 have indicated that seagrass habitat has contracted from historical levels (Lathrop et al 2006; Kennish et al 2007). An estuary wide survey was conducted in the summer of 2009 to measure the current extant of seagrass habitat across the BB-LEH system. To accomplish this goal aerial imagery collected in the summer of 2009 was mapped using an object oriented image analysis techniques. A technique to classify the image objects using a Cartographic and Regression Tree (CART) was compared to the manual method used by Lathrop et al. (2006) in the 2003 survey. The visual interpretation method outperformed the CART method for mapping seagrass presence vs. absence (overall accuracy of 78% automated vs. 87% manual; kappa statistic of 45% automated vs. 73% manual). The categorical values of seagrass density, when compared to the same validation sites, had an overall accuracy of 70% and an unweighted kappa statistic of 47% using the manual classification technique. Results of this work indicate that seagrass habitat expanded when comparing the 2003 and 2009 remote sensing surveys from 5,184 ha in 2003 to 5,253 ha in 2009. Changes in the seasonal period of image acquisition from May 4-5 super( th) in 2003 to July 7 super(th) in 2009 provide information on the location of R. maritima habitat, but also make it difficult to compare between the 2003 and 2009 imagery. Overall seagrass habitat expanded slightly across the estuary system except in areas adjacent to Barnegat Inlet. Future efforts to map seagrass habitat within the BB-LEH should pay particular attention to collect imagery during peak seasonal seagrass biomass, low tide, low wind conditions, and low water turbidity to maximize the spectral difference between seagrass and other benthic habitats.
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Details
- Title
- Distributional change in seagrass as an ecological indicator of estuarine health for Barnegat Bay - Little Egg Harbor, New Jersey
- Creators
- Scott Haag
- Resource Type
- Book
- Language
- English
- Academic Unit
- Computer Science (Computing)
- Identifiers
- 1124419470; 9781124419473; 991021861845404721