GEOSPATIAL TECHNIQUES ON HARMFUL ALGAL BLOOM DETECTION IN THE PHILIPPINE WATERS

MODIS ocean color data ABSTRACT: Occurrence of harmful algal bloom (HAB) or red tide in the Philippines increased from 1980s to present. Since then the Bureau of Fisheries and Aquatic Resources releases bulletin on shellfish bans on areas that are commonly stricken by paralytic shellfish poisoning which is related to occurrence of harmful algal blooms or red tide. The said effort is a response to the increasing prevalence of the issue in the Philippines during the 80s and 90s. However, the bulletin only covers areas with active monitoring activities by the Bureau. Remote sensing can provide enhancement or augmentation to the said effort. In the past years, several bloom detection techniques were studied and applied in different parts of the world. Most of these techniques were based on ocean color data and derived products. Some of these techniques are the chlorophyll concentration anomaly, Red Tide index, Fluorescence Line Height (FLH), particulate backscattering and combination of these techniques. In this study, a modified chlorophyll concentration anomaly and FLH techniques were explored for bloom detection in the Philippine waters. MODIS aqua ocean color from 2002 to 2012 was used in the study. The results of these bloom detection techniques were correlated with shellfish ban database from the BFAR Shellfish Bulletin. Based on the correlation, it was found out that there is higher potential for nFLH bloom detection model than the chlorophyll a concentration anomaly model for detecting occurrence of shellfish toxicity