Spatial and temporal variations in production at the lower trophic levels of tropical aquatic ecosystems (Taal Lake, Ragay Gulf, and Sulu-Celebes Seas) [Philippines]
2003
Castillo, L.V. (Philippines Univ. Los Banos, College, Laguna (Philippines). Inst. of Biological Sciences)
Biological communities in freshwaters. archipelagic and oceanic waters depend primarily on the energy and materials being transfered within the lower trophic levels, from the phytoplankton to the zooplankton. These feeding relationships or trophic structure when presented as biomass pyramids will show the relative abundance of each trophic level. Biomass pyramids may either be upright or inverted depending on the environmental conditions. For the deep, open water of Taal Lake [Batangas, Philippines] and areas where fish cages are concentrated, the biomass pyramid is upright. In shallow areas and coves, inverted pyramids are observed. In Ragay Gulf, an archipelagic water, the biomass pyramids are similar in all stations per monsoon season, an upright pyramid during the Northeast monsoon and inverted pyramid during the Southwest monsoon. Apparently, physico-chemical variations brought about by the monsoons affect largely plankton production. Variations in shapes of biomass even exist in oceanic ecosystems. That is, an upright pyramid exists in the Celebes Sea whereas an inverted pyramid exists in the Sulu Sea. Again, such variations would lead us to consider the forces that shape the biomass pyramids, top-down or bottom-up. An inverted pyramid, which is observed in open water ecosystems essentially, signifies that phytoplankton consumption rate is faster than the production rate such that build-up becomes limited. This results to a community structure that is largely affected by top consumers. On the other hand, an upright pyramid is observed when phytoplankton biomass build-up is higher than what can be consumed. This paper has shown the variations in plankton production in Taal Lake, Ragay Gulf, and Sulu-Celebes Seas as a function of time and space
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