Survey and spatial distribution of shoreline malacofauna in Grande Island, Subic Bay [Philippines]
2011
Batomalaque, G.A. | Arce, B.G.P. | Hernandez, Ma.B.M. | Fontanilla, I.K.C.
Grande Island, Subic Bay [Philippines] is an excellent site for studying spatial distributions on a local scale because of its topographic heterogeneity. This study aimed to provide a systematic survey and spatial distribution of shoreline malacofauna of the island using a total of 956 continuous 2x2 m plots. Substrate types were classified as sand, sand-pebble, rock-sand, rock-pebble, pebble-rock-coral rubble, boulder, and wood. One hundred mollusk species were identified from 44,465 individuals with 54 additional individuals still unresolved. Mollusks were found to be distributed according to the substrate type (composition and particle size) and are independent of the total area sampled. Substrates that are loose or unstable tend to have only few species while those that are compact have more species. Only bivalves were found in the sand substrate. Planaxids, nerites, trochids, and siphonarids were the dominant groups in substrate with rocks, pebbles, and coral rubble. Nudibranchs only occurred in rocky substrates. Nacellids and littorinids predominate particularly in boulders. Littorinids were also numerous in woody substrates. Junevile trochids and planaxids were most abundant in regions with calm water while Cellana species and adult trochids were particular in areas exposed to strong currents. The morphological adaptations of different species enabled them to occur in specific habitat types.
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