Spectral Library of Macroalgae and Benthic Substrates in Estonian Coastal Waters

Merepõhja ja põhjataimestiku optilised omadused Eesti rannavetes

Tiit Kutser ； Ele Vahtmäe ； Liisa Metsamaa

《Proceedings of the Estonian Academy of Sciences. Biology. Ecology》 55卷4期 (2006/12) Pp. 329-340

並列摘要

Benthic algal cover and trends in its changes are indicators of water state in coastal areas. Mapping benthic algal cover with conventional methods (diving) provides great accuracy and high resolution yet is very expensive and is limited by the time and manpower necessary to monitor large bodies of water and long stretches of coastline. Mapping of benthic macroalgal cover by remote sensing requires knowledge about optical signatures of different bottom types. We measured reflectance spectra of red, green, and brown macroalgae, seagrass, sand, pebble, and wet and dry decaying mats of macroalgae and higher plants. Comparing optical properties of the Baltic Sea macroalgae with results of other studies from different parts of the world allows us to conclude that reflectances of three large groups (red, green, and brown algae) are relatively consistent in shape. Most of the variability within the groups occurs in reflectance values. The within-species variability in reflectance values of the brown alga Fucus vesiculosus and the red alga Furcellaria lumbricalis is as great as the variability in reflectance values within brown and red algae groups, correspondingly. This suggests that the feasibility of mapping the benthic macroalgal cover in the coastal waters of the Baltic Sea by remote sensing on species level is highly unlikely. The collected spectral library of the Baltic Sea bottom types allows us to interpret remote sensing data using supervised classification methods, such as Spectral Angle Mapper, which require availability of reflectance spectra of different bottom types. The spectral library together with a bio-optical model allows estimating the suitability of different remote sensing sensors for mapping Baltic Sea bottom types. Thus, collecting the spectral library is an important step in mapping shallow water bottom types by remote sensing.

並列關鍵字

remote sensing ； coastal waters ； benthic macroalgae