Seagrass Monitoring
Long-term seagrass monitoring commenced in August 2011 at PAIS and GUIS. Field crews (working under Task Agreements through the Gulf Coast CESU) from University of Texas Marine Science Institute (PAIS) and Dauphin Island Sea Lab (GUIS) initiated a protocol developed by the USGS and implemented throughout the Northeast Coastal and Barrier Network (NCBN). The protocol is based on seagrass metrics (species composition, canopy height, percent coverage) and water quality measures (temperature, pH, dissolved oxygen, salinity, turbidity, chlorophyll-A, and Secchi depth). A tessellated hexagon net (750 m edges) is draped over the sampling frame (mapped seagrass beds within park waters) and a random point is generated for each hexagon which serves as a permanent station that will be occupied (within 10 m) each year for repeated monitoring. This protocol now provides monitoring conformity throughout Texas seagrass beds (NOAA and the Texas General Land Office have funded monitoring on most non-park beds), the GULN parks, and the parks of the NCBN.
Figure 1A: A hexagon layer superimposed on the seagrass resources (red lines) of the Florida Gulf Islands National Seashore. Hexagons (white lines) have an edge distance of 750m.
Figure 1B: A hexagon layer superimposed on the seagrass resources (red lines) of the Mississippi Gulf Islands National Seashore. Hexagons (white lines) have an edge distance of 750m. Seagrass resources were determined using 2009 aerial photography provided by the Mobile Bay National Estuary Program.
Figure 2. A hexagon layer superimposed on the seagrass resources (green areas) of the Upper Laguna Madre. Hexagons (red lines) have an edge distance of 750 m. Hexagons were tesselated over the entire extent of the seagrass beds, classified as "Continuous SRV" in the NOAA Benthic Habitat Mapping. A 'minimum seagrass coverage' threshold was applied within each hexagon to prioritize monitoring activities. The 50% threshold applied (as minimum percent of seagrass within each hexagon) and the resulting number of stations (n = 144) are identified in text on the map.