Hyperspectral aerial images. A valuable tool for submerged vegetation recognition in the Orbetello Lagoons, Italy

Results obtained in mapping algal belts in the Orbetello Lagoons are described using Daedalus/MIVIS hyperspectral scanner aerial images. MIVIS has a spectral coverage in the Visible, Near-IR, Mid-IR and Thermal-IR regions, with 102 channels. The objective of the work is a procedure for the algal species recognition, using methods of spectral data analysis. The 1-2 m deep brackish, shallow water basin areas of the Orbetello Lagoons have poor water circulation and considerable eutrophication phenomena. During MIVIS overflight, spectra of submerged vegetation (Cymodocea sp., Cladophora sp., Chaetomorpha sp., Gracilaria sp., Enteromorpha sp., Ruppia sp. and Ulva sp.) were collected from a boat equipped with a field portable multi-spectral radiometer operating between 380 and 780 nm. In situ collected spectra and MIVIS spectra, in the visible and the near infrared region for prototype area, were compared to select the representative spectra of submerged vegetation. The Spectral Angle Mapper (SAM) has been the method adopted for the spectral classification.