Collection of the clam Anodontia edentula in mangrove habitats in Panay and Guimaras, central Philippines
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The mangrove clam Anodontia edentula is highly prized in the Philippines for its flavor and large size. Because this infaunal species is found down to one meter deep in mangrove areas, harvesting the clam reportedly damages mangrove stands. To evaluate such reports, a survey of collection methods was undertaken in Panay and Guimaras, central Philippines in August 1997-December 1999. Host to chemosynthetic bacterial symbionts that utilize sulfide as energy source, A. edentula are strategically situated in sulfide-rich anoxic substrates but also gain access to oxygenated seawater through a ventilation burrow or tube. By locating the opening of this burrow, collectors can detect the presence of a buried clam and harvest it nondestructively with a blade or bare hands. In contrast, the indiscriminate tilling of wide mangrove areas can damage mangrove plants. Most collectors were 40-45 years old with 22-30 years collection experience, married with 5-7 children, and had low educational attainment. They sold clams directly in the local markets or through middlemen (to restaurants and beach resorts); sales provided from 10% to 100% of daily family income. Collectors complained of decreasing clam sizes and numbers and the physically strenuous work of collecting.
CitationPrimavera, J. H., Lebata, M. J. H. L., Gustilo, L. F., & Altamirano, J. P. (2002). Collection of the clam Anodontia edentula in mangrove habitats in Panay and Guimaras, central Philippines.
PublisherKluwer Academic Publishers
Burrowing organisms; Chemosynthesis; Clam fisheries; Ecosystem disturbance; Environment management; Environmental impact; Harvesting; Mangrove swamps; Plant populations; Shellfish; Sulphides; Symbionts; Bacteria; Food security; Anodontia edentula; Gleaning; Lucinid bivalve; Mangrove clam; Bacterial symbionts
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Oxygen, sulphide and nutrient uptake of the mangrove mud clam Anodontia edentula (Family: Lucinidae) MJHL Lebata -
Marine Pollution Bulletin, 2001 - ElsevierOxygen, sulphide and nutrient (ammonia, nitrite and phosphate) uptake of Anodontia edentula was measured. Oxygen and sulphide were measured from sealed containers provided with 1 l fresh mangrove mud (sulphide source) and seawater (oxygen source) with two treatments (with and without clam) at 16 replicates each. Oxygen, sulphide and other parameters were measured at days 1 (initial), 3 and 5 (final). Nutrients were measured from containers filled with 1.5 l wastewater from a milkfish broodstock tank with two treatments (with and without clam) at eight replicates each. Ammonia, NO2 and PO4 were measured at days 0 (initial) 3, 6, 9 and 12 (final). Results showed significantly decreasing oxygen and sulphide concentrations in treatment with clams (ANOVA, p < 0.001). A significantly higher ammonia concentration (ANOVA, p < 0.05) was observed in treatment with clams while no significant difference was observed in nitrite and phosphate between the two treatments. A decreasing ammonia and an increasing nitrite trend was also observed in both treatments starting at day 3.
ArticleJHL Lebata -
Journal of Shellfish Research, 2000 - National Shellfisheries AssociationDifferent sizes of the mangrove mud clam Anodontia edentula were collected from the mangroves in Brgy. San Roque in Estancia, Iloilo, central Philippines, and the mantle, gill, and foot tissues were analyzed for elemental sulfur content. Mangrove mud (substrate) was also analyzed for total sulfur content to establish the possibility of clam-bacteria symbiosis in this lucinid clam. Sulfur analysis showed highly significant (p <0.0001) amounts of elemental sulfur in the gills (247.64 ± 63.28 μmoles/g FW) compared with the quantities observed in the mantle (0.84 ± 0.22 μmoles/g FW). Elemental sulfur was absent from the foot tissues. Results also showed a significantly (p <0.05) decreasing elemental sulfur from the newly collected clams (mean = 461.18 μmoles/g FW) compared to those reared in the laboratory (mean = 159.08 μmoles/g FW: with mangrove mud substrate; mean = 45.18 μmoles/g FW without substrate), which were analyzed weekly until week 3, indicating that stored elemental sulfur is being utilized by the bacteria in the absence of sulfide. Total sulfur content of mangrove mud in situ was higher than that used us substrate in the experiment; where there were no significant differences from initial to final readings. This shows that mangrove mud in situ is linked to a steady sulfur source.
Biology and status of aquaculture for giant clams (Tridacnidae) in the Ryukyu Islands, southern Japan K Iwai, K Kiso & H Kubo - In JH Primavera, ET Quinitio & MRR Eguia (Eds.), Proceedings of the Regional Technical Consultation on Stock Enhancement for Threatened Species of International Concern, Iloilo City, Philippines, 13-15 July 2005, 2006 - Aquaculture Department, Southeast Asian Fisheries Development Center