Palaeolimnological studies of Laguna de Bay, Philippines: Evidence from diatoms

Abstract

1. Two sites were chosen at Bagong Kalsada, by the Villa Resort at Calamba, Laguna de Bay, Philippines. 2. One core of 216 cm depth was collected at each site. 3. Diatom species have been recorded at 24 cm intervals from the 2 cores. 4. At Site 1 near the fish ponds, algae indicative of a littoral habitat were found at the base of the core (Core I) giving way to lower total diatom counts of organic tolerant species in the wetter, gray soil of the middle zone which probably indicates a higher lake level at this period. The uppermost zone was drier and brownish in colour with much higher diatom numbers consisting of species tolerant to higher suspended solids, indicative of the increase from run-off water following deforestation on the lake shores. 5. Core II lacked the sandy bottom zone and was much wetter than Core I at Site 1. The total diatom numbers were higher in this zone than in comparable depths in Core I except at the very bottom of the core. The bulk of the species present were typical of eutrophic conditions and tolerant to organic pollution. The middle of the core was much drier than the equivalent area in Core I and the diatom population was represented by species tolerant to high suspended solids and more typical of muddy rather than sandy habitats, but still tolerant to eutrophic conditions. In the upper-most zone, in the moist, brown clay, the numbers of diatoms declined rapidly but showed similar diversity to the middle zone. 6. Details are given of the stratigraphy of individual diatom species and their known tolerance ranges for various physico-chemical factors.

Source or Periodical Title

Limnologica

ISSN

759511

Page

165-177

Document Type

Article

Subject

Cores, Diatoms, Palaeoecology, Philippines

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