Abstract

This study was undertaken to provide biological information on the species distribution and abundance of sea stars as well as the physico-chemical status of the seawater of selected intertidal zones of Davao Gulf for sustainable use of marine resources. This study was conducted along the 10 selected intertidal zones of Davao Gulf specifically in Davao City, Philippines. Results showed a total of 2357 individuals identified. These species belong to 8 genera and 4 families of sea stars. Of these, 1842 species belong to family Astropectinidae, 484 species are under the family of Ophidiasteridae, 30 species for family Oreasteridae, and 1 species in the family of Acanthasteridae.

Sampling was done from September 2010 to March 2011. The study revealed a diversity index of 28.45% using Shannon-Weiner showing low species richness and evenness. Majority of the sampling area (80%) are composed of sandy substrate while 20% have silty and muddy substrate. Of the sandy substrate, 30% of which have coral rubble, 40% have sea grasses and only 10% were observed with living corals. Species richness generally increases with increasing water quality, habitat diversity and or habitat suitability and is expected to decrease with human induced disturbance. Although statistics revealed there were no significant relationship between the number of sea star species and the physico-chemical parameters except for the BOD which recorded a much lower value compared to the criteria set by the government. Literature readings cites the possibility that the temperature might be the cause of the sudden change of BOD since temperature affects the rate of photosynthesis of plants, the metabolic rate of aquatic animals, rates of development, timing and success of reproduction, mobility, migration patterns and the sensitivity of organisms to toxins, parasites and diseases.

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