Culture Studies on Four Selected Phytoplankton Isolated from Freshwater Tributaries Connected to Carigara Bay

Abstract

Carigara Bay is one of the successful fishing areas in the entire Philippines because of its multi-gear fishery system. Filipinos living around the bay consider its marine life as one of the sources of their livelihood. However, the biodiversity and biological importance of phytoplankton are still unexplored as evidenced by the dearth of published data in scientific journals, thus, this study was undertaken. Sampling sites are the freshwater tributaries namely Lindog River [Brgy. Uyawan], Bislig River [Brgy. Bislig] situated in Carigara, Himanglos River [Brgy. Hilaba], Canomantag River [Brgy. Canomantag] in Barugo, stream located in Brgy, Libertad, Capoocan, Caraycaray River [Brgy. Caraycaray], Lipasan falls [Brgy. Pinarigusan] in San Miguel and Tula-an falls [Brgy. Tula-an], Busay falls [brgy. Busay] in Babatngon. Water samples from the sampling sites were collected using a 2.5-3L plexi glass sampler, transferred in three [3] 1L cap bottle and brought in the laboratory for processing. All data were subjected to statistical analyses such as two-way analysis of variance [ANOVA] and Post-hoc test. Culture studies were conducted on selected phytoplankton namely the Asterococcus cf limneticus; Chlorococcum cf humicola; Anabaena cf azollae and Oscillatoria cf limnetica. The species were selected and further subjected to optimization due to their fast-growing ability in a span of time, less bacterial contamination compared with the others and their ability to withstand varying conditions of light, temperature and pH. The four phytoplankton were optimized in terms of light intensities, pH and temperature. Cell density was measured every two days using the haemacytometer method and specific growth rates were computed. Results show that the four phytoplankton have the highest specific growth rates at 40.5 umol m^-2 s^-1, 25⁰C and pH 7. These measurements form the basis of microalgae cultivation in great quantities for the production of natural food and processing of pharmaceutical and other industry products. The optimized microalgae namely Asterococcus cf limneticus; Chlorococcum cf humicola; Anabaena cf azollae, Oscillatoria cf limnetica have high ash, protein and lipid contents which are vital nutrients for food and supplement development.