Practical techniques for mapping small patches of mangroves
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Practical mapping methods employing GPS field surveys and manual image analyses with affordable software were used to assess two mangrove sites in Aklan Province, NE Panay Island, central Philippines. The Jawili mangroves, absent from current maps, actually included 21.5 ha with 24 true mangrove species. On the other hand, the Batan Estuary mangroves, shown to be 4244 ha in available topographic maps, revealed only 406 ha of scattered patches. Actual mangrove data on specific areas worldwide is limited, especially in the Philippines where available maps show discrepancies from actual mangrove distribution. Remote sensing (RS) techniques provide promising results but require expensive setup, particularly for small areas. Therefore, financially limited users need affordable and rapid mapping alternatives. The practical techniques presented here can be immediately implemented at minimal cost and can produce useful estimates of actual mangrove area, fundamental for coastal management. Basic principles used here also have potential applications in other systems and locations. When resources are available though, additional confirmation and precise mapping are also further recommended.
CitationAltamirano, J. P., Primavera, J. H., Banaticla, M. R. N., & Kurokura, H. (2010). Practical techniques for mapping small patches of mangroves.
Topographic maps; Estuaries; Remote sensing; Wetlands; Mapping; Manuals; Patchiness; Mangroves; Coastal zone management; Computer programs; Software; Data processing; Islands; Image processing; Remote sensing; Costs; Surveys; Maps; Mangrove swamps; Digitized map; GPS tracking; Mapping; Philippine mangroves; Rapid assessment; GIS; Aerial Photographs; Management; Ecosystems; Patterns; Ikonos; Coast; Philippines
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Enhancing disease monitoring in shrimp through a geographical information system (GIS) application SEAFDEC Aquaculture Department (AQD) pioneered fish disease work in the Philippines and developed diagnostic tools through research. Its Diagnostic Service Laboratory was established in the late 1970s to serve the budding aquaculture industry. Through the assistance of SEAFDEC AQD, this service has been replicated by both private and government agencies involved in shrimp aquaculture, thus, data on disease occurrence and prevalence are already available in databases in various forms. Laboratory analysis of hatchery-reared shrimp postlarvae has become an important tool for marketing using both physical and health attributes as gauges for acceptance or rejection of specific batches. Through the years, the diagnostic tools have evolved from mere wet mount microscopy to molecular diagnostic techniques by means of polymerase chain reaction (PCR) to detect viruses. Despite this development, however, disease information is still patchy and difficult to use as decision-support tools because it remains in highly technical and in difficult to visualize information spreadsheets and tables. GIS is a tool that translates complex data in tables and spreadsheets into maps that provide visual displays of information in both spatial and temporal forms. It shows disease trends that are not presently seen and understood by all stakeholders. This paper will highlight the evolution of shrimp health monitoring as a marketing tool in the Philippines and how the application of GIS has helped in understanding disease patterns in the shrimp industry.
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