Sargassum spp. are brown macroalgae that serve a critical ecosystem
function in pelagic regions such as the Gulf of Mexico and the Atlantic.
Hu, Feng, Hardy and Hochberg (2015-in this issue) evaluate the spatial
and spectral requirements needed to discriminate Sargassum from spectrally
similar materials including other marine algae, marine garbage
and oil emulsions. They evaluate this potential using observations
from a diversity of multispectral and hyperspectral systems imaging
Sargassum, including data acquired by MODIS, Landsat, and
WorldView-2 broad band systems, as well as hyperspectral data acquired
by HICO and AVIRIS. To evaluate minimum cover limits for detection
and identification, they employ a mixing model, finding that
Sargassum identification requires a minimum of 20–30% cover, but
only 1–2% cover to detect the presence of the marine algae. HyspIRI,
with improved spectral, spatial and radiometric properties (signal-tonoise
ratio), provides a good compromise between spatial coverage,
and spatial resolution with the wavelengths needed for discrimination