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MAPPING GREEN MACROALGAE BLOOMS IN A PACIFIC NORTHWEST ESTUARY VIA 35-MM AERIAL PHOTOS
Citation:
Young, D R., P J. Clinton, D T. Specht, AND S P. Cline. MAPPING GREEN MACROALGAE BLOOMS IN A PACIFIC NORTHWEST ESTUARY VIA 35-MM AERIAL PHOTOS. Presented at Pacific Estuarine Research Federation Annual Meeting, Sydney, B.C., Canada, May 11-13, 2000.
Description:
Summer blooms of green macroalgae (mainly Ulva spp. and Enteromorpha spp.) on intertidal mudflats of Oregon's Yaquina Bay estuary were documented using oblique 35-mm color-infrared aerial photographs taken at low tide. Costs were controlled by use of a small airplane from a local airport. The slide film was digitized and georeferenced to digital orthophotographs of the estuary obtained from large-format aerial photos. Corresponding ground surveys conducted between June and December, 1999, provided reference data on distributions of native eelgrass (Zostera marina) vs. green macroalgae. Although digital classification of the aerial images did not distinguish between these taxa, the approach did accurately map the combined distributions. Using GIS, the fixed eelgrass beds then can be masked to reveal the temporal trend through the growth season of green macroalgae at higher elevations on the intertidal mudflats.