An Assessment of the Benthic Community Structure: Implications on the Water
Quality of Lake Palacpaquen, San Pablo City, Philippines
Perez, T, Caasi, H., and de la Torre, J.
Department of Environmental Science, Ateneo de Manila University,
Loyola Heights, Quezon City, Philippines
Lake Palacpaquen is the shallowest and second largest lake in the Seven Lakes of San
Pablo City, Laguna, Philippines. The lake is threatened by water quality deterioration
caused by anthropogenic activities. The benthic macroinvertebrate community of the lake
was investigated. The impact of water quality deterioration on the benthic community
was evaluated using the Belgian Biotic Index (BBI) and the Family-Level Biotic Index
(FBI). Samples were obtained from four stations in the lake: inlet, pool, periphery and
outlet and in-situ water quality parameters were measured. Substrate varied from organic
litter (leaves, twigs, roots) to gravel and fine sediments. DO concentrations and turbidity
were generally lower in November while pH level, temperature and conductivity were
lower in December, following a series of heavy rainfall.
Dominance of mollusca genera Melanoides, Tarebia, Bellamya and Angulyagra were
observed to dominate. Six other genera of mollusks were found, including the bivalve
Corbicula and the foreign species, Pomacea canaliculata. Larvae of the Family
Chironomidae were abundant in the pool.
Taxa diversity was highest in the periphery and the lake outlet in December and January.
Diversity of the entire lake obtained from composite samples was highest in January (H’=
0.834). BBI scores were lowest in November and highest in January for all sites. Based
on the BBI, Lake Palacpaquen was moderately polluted in November and December, and
was lightly polluted to unpolluted in January. FBI scores were lowest in January (6 =
fairly poor), but this rating is still indicative of the possibility of substantial pollution.