Taxonomy distribution and temporal changes in the phytoplankton community in Taal Lake, Philippines
2006
Enriquez, E. | Perez, T.
Taal Lake, a volcanic lake and a tourist spot in the Philippines, has a great contribution to the country's economy, being one of the sources of commercial fishes distributed to nearby Metro Manila. Aquaculture practices and nutrient inputs have contributed a great deal of disturbance to the lake's ecosystem. To investigate the lake's present nutrient status and biological composition (phytoplankton), a ten-month study on the lake was conducted from October, 1999 to July, 2000. Other environmental parameters were also recorded, such are the waters' conductivity, total dissolved solids (TDS), alkalinity (pH), and temperature. A significant increase in NH4-N was observed from June and July, 2000. A significant increase in total P, soluble P and NO3-N was observed during the dry season from the monthly collections conducted. Though there was a significant increase in the nutrient hold of the lake, there was no significant correlation between the nutrient and the chl a content of the lake from all three collection sites. On the other hand, TDS (p greater 0.05), pH, and temperature (p greater 0.001) showed positive correlation with chl a concentration. There was no significant difference between depth observed among the nutrients and other physico-chemical factors. There was also no significant increase in the monthly chl a collected, although a significant amount of chl a was observed from 2.5m and 5 m depth. Ceratium, centric diatoms, Aulacoseira and Merismopedia showed high cell counts (p greater 0.001). Collections from May and July, 2000 showed significantly high individual cell counts among the rest of the collection months, with a corresponding high chl a concentration. The four dominant genera mentioned above also showed positive correlation with TDS, pH, temperature, NO3-N, and NH4-N generated from the CCA.
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