Seagrass Mapping and Monitoring Along the Coasts of Crete, Greece

Current presentation introduces a MSc thesis defense. The research focuses on the P. oceanica, an endemic species of the seagrass in Mediterranean Sea. Study area is Crete Island, Greece. The goal of this study is to analyse optical properties of the seagrass P. oceanica and other seafloor types (carbonate sand), and to apply remote sensing techniques for seagrass mapping in the selected locations of northern Crete. Analyzing spectral reflectance of the P. oceanica and other seafloor cover types by means of tools Radiative Transfer Model (RTM) using Water Color Simulator (WASI). Other technical tools included ArcGIS and Erdas Imagine GIS software, Gretle for plotting and statistical analysis, SPSS for ANOVA based Hypothesis testing. Data include spectral measurements of the seagrass optical properties by Trios-RAMSES (Hyperspectral radiometers for measuring optical properties of water), Google Earth aerial images, Landsat TM scenes. Fieldwork measurements were done using iPAQ data and GPS records, SCUBA equipment. Optical properties of the water columns were tested : spectral reflectance, radiance, irradiance. Characteristics reflect current chemical content and physical specifics of the water with and without sediments. Results of this research proved that P. oceanica is spectrally distinct from other seafloor types (carbonate sand) at varying environmental conditions, as well as from other seagrass species (Thalassia testudinum). The RTM software is a useful tool for analyzing spectral signatures of various seafloor types enabling simulations of data received from the broadband and narrowband remote sensors. Application of the RS data from the broadband sensors is highly advantageous for the seagrass mapping. Spectral discrimination of P. oceanica from other seafloor cover types is possible at diverse and changing environmental conditions (water column height). Maps, graphics and imagery are provided. Current presentation contains 72 slides. Defended at University of Twente, Faculty of Earth Observation and Geoinformation (ITC), Enschede, Overijssel Province, the Netherlands on March 8, 2011.