Abstract
In this study we produced the first thematic maps of submerged and coastal habitats of Lampi Island (Myanmar) from in situ and satellite data. To focus on key elements of bio-diversity typically existing in tropical islands the detection of corals, seagrass, and mangrove forests was addressed. Satellite data were acquired from Landsat-8; for the purpose of validation Rapid-Eye data were also used. In situ data supporting image processing were collected in a field campaign performed from 28 February to 4 March 2015 at the time of sensors overpasses. A hybrid approach based on bio-optical modeling and supervised classification techniques was applied to atmospherically-corrected Landsat-8 data. Bottom depth estimations, to be used in the classification process of shallow waters, were in good agreement with depth soundings (R2 = 0.87). Corals were classified with producer and user accuracies of 58% and 77%, while a lower accuracy (producer and user accuracies of 50%) was found for the seagrass due to the patchy distribution of meadows; accuracies more than 88% were obtained for mangrove forests. The classification indicated the presence of 18 mangroves sites with extension larger than 5 km2; for 15 of those the coexistence of corals and seagrass were also found in the fronting bays, suggesting a significant rate of biodiversity for the study area.
Highlights
In tropical marine systems, corals, seagrass, and mangrove forest habitats provide important ecosystem services, both individually and through their functional linkages; e.g., coral reefs protect the coastline from erosion and prevent damage to and/or loss of seagrass beds and mangrove forests [1,2].Coral reefs play a significant role in the supply of sediments or sands to beaches
The spatial and temporal dynamics of these processes may be different from site to site, as different threatening occurs, and marine protected areas (MPAs) have been highlighted as a means toward effective conservation of coral reefs, seagrass meadows, and associated biodiversity [1]
To provide an accuracy of the results depicting the spatial distribution of mangrove forests, Tosea provide an accuracy of matrixes the resultswhere depicting the spatial distribution mangrove forests, and corals, and grasses confusion computed based on bothoffield observations corals, and sea grasses confusion matrixes where computed based on both field observations and of higher spatial resolution RapidEye data (Figure 7)
Summary
Corals, seagrass, and mangrove forest habitats provide important ecosystem services, both individually and through their functional linkages; e.g., coral reefs protect the coastline from erosion and prevent damage to and/or loss of seagrass beds and mangrove forests [1,2]. The spatial and temporal dynamics of these processes may be different from site to site, as different threatening occurs, and marine protected areas (MPAs) have been highlighted as a means toward effective conservation of coral reefs, seagrass meadows, and associated biodiversity [1] In this context, remote sensing is a powerful tool to obtain unique spatial and temporal information about the components that characterize marine and terrestrial ecosystems. By using in situ and Landsat-8 data, we exploited a hybrid approach combining classification techniques and bio-optical modelling for mapping corals, seagrass and mangrove forests in the entire LIMNP This allowed identifying bays where these ecosystems are interconnected and to select priority areas to be preserved in future management strategies. Higher spatial resolution RapidEye data provides a further validation for the substrates classification in shallow waters
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