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February 10, 2015
Dewberry Mapping Initiatives Document Seagrass Habitat Levels

Fairfax, Va, Feb. 9, 2015—Environmental mapping projects in Florida and California document the decline of seagrass, an aquatic plant vital to estuarine ecosystems and regional economies.

Two environmental mapping projects recently completed in Florida and California are helping to document the decline of seagrass, an aquatic plant that is vital to estuarine ecosystems and regional economies. Dewberry, a privately held professional services firm based in Fairfax, Virginia, has updated maps of the 156-mile Indian River Lagoon and adjacent estuaries for the St. Johns River Water Management District in Florida, an effort that enables the district to quantify gains and losses of seagrass habitat. Dewberry has also prepared new maps of wetlands and seagrass within a 991-mile area of San Francisco Bay for the National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center.

Seagrass, a submerged flowering plant found in shallow marine waters, provides food, habitat, and nursery areas for numerous vertebrate and invertebrate species. The distribution and extent of seagrass is considered a barometer of the health and water quality of estuarine systems, which are critical to maintaining biodiversity and supporting commercial and recreational fisheries.

Dewberry mapped the Indian River Lagoon and adjacent estuaries in 2011 using aerial photography and field work involving GPS, snorkeling, and underwater video. The 2011 data showed a decline in seagrass of approximately 60 percent over 2009 findings.

The new maps depict 2013 conditions and enable the district and other stakeholders to track seagrass presence, study the impacts of algae superblooms, and devise strategies to restore the lagoon's ecosystem. The data will also help determine acceptable Total Maximum Daily Loads (TMDL) within the system, a calculation of the maximum amount of pollution a water body can receive and still meet minimum water quality standards.

The digital aerial photography of the lagoon was captured according to several time-sensitive requirements, including the absence of turbidity in the water, a sun angle between 15 and 30 degrees, and no wind or clouds. Dewberry monitored lagoon conditions before authorizing imagery collection. Field work documentation and the mapping were delivered within an ArcGIS geodatabase.

The project for NOAA's Coastal Service Center mapped San Francisco Bay, the largest estuary in California. Baseline mapping, which required similar technology and equipment as the work in Florida, will assist the Coastal Services Center and regional, state, and local partners with long-term seagrass and wetland monitoring, trend analysis, and conservation efforts. Along the West Coast, the Pacific Fishery Management Council has identified seagrass as one of the region's Habitat Areas of Particular Concern (HAPC).

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