MAPPING ALGAL BLOOMS USING AIRBORNE DIGITAL MULTISPECTRAL VIDEO AND THE IMPORTANCE OF BLOOM DYNAMICS IN THE COLLECTION OF IN-WATER DATA

Between January 18-20, 1995, a dinoflagellate algal bloom occurred in the Swan River, Western Australia. An airborne Digital Multi-Spectral Video (DMSV) system was used to acquire data on the bloom several time s a day for three days. Simultaneous in-water data were gathered to de termine the temporal and spatial dynamics of the algal concentrations. The study demonstrated the highly dynamic nature of algal, blooms in space, depth, and time (within and between days), but the DMSV, limite d by the existing band combinations, failed to show a strong qualitati ve relationship between physical and biological measurements. The resu lts indicate that, to describe the bloom best, the timing of airborne data acquisition must be timed to coincide with movements of phytoplan kton within the water column (such as daily afternoon migration of cel ls to the surface waters) and times of the day that will minimize sun- glint. Furthermore, ground truthing to calibrate or validate images mu st be carried out within a short period of airborne data acquisition b ecause of the dynamic nature of the distributions of the phytoplankton cells. When blooms are rapidly changing, in-water sampling over large spatial scales, within short time spans, may be logistically impossib le. In these situations, remote sensing provides an effective tool to capture the dynamic nature of the blooms in a qualitative sense.