AbstractCalculating Bathymetric and Spatial Distributions of Estuarine EelgrassTrack: Ocean, Coastal, and Marine Resources Author Distributions of native eelgrass Zostera marina within the intertidal and shallow subtidal zones of three Oregon estuaries (Tillamook, Yaquina, and Alsea) were classified from color infrared aerial orthophotography acquired at extreme low tide. Image processing software, Spatial Analyst algorithms and ArcScan editing were used to classify the imagery. Classification accuracy was measured by comparing >10% field point intercept count with >10% classification raster FocalSum results. Overall accuracies ranged from 84 to 100 percent. Bathymetric soundings were interpolated using TopoGrid, combined with eelgrass rasters and exported for pivot table analysis. Over 90 percent of the surface-visible eelgrass in the estuaries occurred within the depth interval -0.9 m (-3 ft) to +0.9 m (+3 ft) relative to Mean Lower Low Water. Depth distributions of eelgrass were also calculated by river kilometer and salinity gradient. Results of the analysis highlight similarities and differences in eelgrass depth distribution in geomorphically differentiated estuarine ecosystems. Patrick Clinton U.S.EPA NHEERL/ORD/WED/PCEB 2111 SE Marine Science Drive Newport, Oregon 97365 United States Phone: 541-867-5003 Fax: 541-867-4049 E-mail: clinton.pat@epa.gov David Young U.S.EPA 2111 SE Marine Science Drive Newport, Oregon 97365 United States Phone: 541 867 2038 Fax: 541 867 4049 E-mail: young.david@epa.gov |