Geographic Information System As a Modeling Tool in the Study of the Reef System of Southern Okinawa

Abstract / Excerpt:

Geographic Information Systems (GIS) was used as a modelling tool in the study to try to predict the probable areas where coral larvae would ultimately settle and survive in the reefs around Southern Okinawa. The first step involved the processing of a Landsat satellite image to produce a marine benthic habitat map. This process utilized a depth compensation algorithm to produce not only a single thematic map, but a set of multiple maps showing the probability values for each of the categories selected. Each of these produced images was assessed for their accuracy with the results showing only moderate accuracy, which is typical in contemporary literature. The images produced (i.e., carbonate probability cover,sand probability cover, land areas, deep water areas) together with other derived images (distance from offshore reefs image, chlorophyll a image) were used as spatial evidence to produce a suitability map showing the areas where coral larvae from the offshore reefs with most likely setle and most likely survive in the intertidal areas of Southern Okinawa. Results show that the bay areas in the eastern side of Okinawa as having very low probabilities of settlement and survivorship of larvae from the offshore reef source. It is argues that this might be one of the reasons why these areas with very good coral cover 30 years ago are now mostly just dead reefs.

Full Text

Geographic Information Systems (GIS) was used as a modeling tool in the study to try to predict the probable areas where coral larvae would ultimately settle and survive in the reefs around Southern Okinawa. The first step involved the processing of a Landsat satellite image to produce a marine benthic habitat map. This process utilized a depth compensation algorithm to produce not only a single thematic map, but a set of multiple maps showing the probability values for each of the categories selected. Each of these produced images was assessed for their accuracy with the results showing only moderate accuracy, which is typical in contemporary literature. The images produced (i.e., carbonate probability cover,sand probability cover, land areas, deep water areas) together with other derived images (distance from offshore reefs image, chlorophyll a image) were used as spatial evidence to produce a suitability map showing the areas where coral larvae from the offshore reefs with most likely setle and most likely survive in the intertidal areas of Southern Okinawa. Results show that the bay areas in the eastern side of Okinawa as having very low probabilities of settlement and survivorship of larvae from the offshore reef source. It is argues that this might be one of the reasons why these areas with very good coral cover 30 years ago are now mostly just dead reefs.

Info
Source JournalAgham Mindanaw
Journal VolumeAgham Mindanaw Vol. 1
AuthorsFrancis Fletcher M. Freire
Page Count4
Place of PublicationDavao City
Original Publication DateJanuary 1, 2003
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