Remote Sensing of Shallow Coastal Benthic Substrates: In situ Spectra and Mapping of Eelgrass (Zostera marina) in the Gulf Islands National Park Reserve of Canada

Eelgrass (Zostera marina) is a keystone component of coastal ecosystems. However, anthropogenic pressures have caused community decline worldwide. Delineation and continuous monitoring of eelgrass distribution is an integral part of understanding these pressures and effectively managing them. A proposed tool for monitoring is remote imagery. However, to apply this technology, an understanding is required of the spectral behavior submerged coastal substrates. In this study, in situ abovewater hyperspectral measurements were used to define key spectral variables providing greatest separation between Z. marina and associated substrates. The selected variables were: slope500-530nm, first derivatives (R’) at 566nm, 580nm, and 602nm, and yielded 98% overall classification accuracy. Classification of a hyperspectral airborne image showed a major advantage of variable selection was meeting band sample size requirements of the maximum likelihood classifier, which yielded classification accuracies of over 85%.