Checklist and illustrations of diatoms in Laguna de Bay, Philippines, with reference to water quality

Abstract

A taxonomic survey of the diatom flora of Laguna de Bay, the largest lake in the Philippines, was conducted with special reference to the slightly brackish and heavily polluted water quality. Based on samples collected in 1976 and 1997, we identified 83 diatom taxa belonging to 37 genera. They are illustrated here together with 15 unidentified taxa. The predominant genus in term of species richness was Gomphonema, represented by 12 species. Nitzschia and Navicula were subdominant each represented by 10 species. A euhalobic species, Giffenia cocconeiformis, occurred despite the low salinity (<0.4‰). Regardless of the heavy organic content and high phosphorus concentration of the lakewater, saprophilous species were not common, and some saproxenous species occurred.