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Journal Articles - UP - MSI

Permanent URI for this collectionhttps://repository.unesco.gov.ph/handle/123456789/50

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AGROVOC Keyword: search.filters.agrovoc.clamsScientific name: search.filters.scientificname.Hippopus porcellanus

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    Diversity of dinoflagellate symbionts (zooxanthellae) in a host individual
    Carlos, A. A.; Baillie, B. K.; Maruyama, T. (Inter-Research Science Center, 2000)
    Zooxanthellae are phototrophic dinoflagellates that exist in symbiosis with a variety of marine invertebrates. The traditional view of zooxanthella-invertebrate symbioses suggests that individual hosts harbor taxonomically homogeneous symbiont populations. To assess the diversity of the zooxanthella assemblage inhabiting an individual host, zooxanthellae from 6 species of clam (Tridacna gigas, T. squamosa, T. crocea, Hippopus hippopus, H. porcellanus and Corculum cardissa) and 1 species of sea anemone (Aiptasia sp.) were studied using temperature-gradient gel electrophoresis (TGGE), coupled with polymerase chain reaction (PCR) using zooxanthella-specific primers that were designed to target hypervariable regions of the small subunit ribosomal RNA (ssrRNA) gene. Results revealed that 1 clam may harbor 2 or more genotypically distinct zooxanthellae, with 1 or more dominant taxa occurring at a time. The clams studied associated with at least 4 zooxanthellar taxa. Nucleotide sequencing of the TGGE bands and phylogenetic reconstruction revealed that the zooxanthellar taxa in clams were Symbiodinium spp.; 1 was identical to previously cultured clam symbiont isolates, 1 appeared identical to a previously studied unculturable clam symbiont, and the other 2 clams represented novel strains of Symbiodinium. Individual Aiptasia sp. harbored only 1 zooxanthellar taxon, which had a ssrRNA sequence identical to that of S. pulchrorum, previously isolated from Aiptasia pulchella. This study has shown that individual tridacnid and cardiid clams can harbor heterogeneous zooxanthellae.
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    Declining population of giant clams (Cardiidae:Tridacninae) in Palawan, Philippines
    Dolorosa, Roger G.; Mecha, Niño Jess Mar F.; Bano, Jemima D.; Ecube, Krizia Meryl A.; Villanueva, Elmer G.; Cabaitan, Patrick C. (FapUNIFESP (SciELO), 2024)
    For more than two decades, the Philippine government has protected the giant clams (Bivalvia: Cardiidae: Tridacninae) from exploitation and trade. However, there still is lack of information on the impact of these protective measures in conserving the species richness and density, especially in Palawan, the country’s last stronghold of these reef-associated bivalves. Hence, to assess the species richness and density of giant clams in Palawan, we conducted 57 photo-transect surveys in six sites covering 12,325 m 2. Out of these transect, 15 measured 5 × 25 m and the rest measured 5 × 50 m. For historical trends in the population of giant clams in Palawan, we used six published papers obtained from online platforms, 13 reports, and five undergraduate theses archived in local libraries. Information derived from recent field surveys indicated high variations in species richness (2 to 5 species) and densities (0.1 to > 3.6 ind.100 m -2). Historical data starting from 1984, including recent fieldwork, indicated very low densities and a declining trend. The current status suggests that giant clam populations’ viability and the reefs’ health are threatened. Effective mechanisms are needed to safeguard and enhance the remaining giant clam populations.
    This paper is an output of the research project: Evaluating the status of giant clams in Palawan (QMSR–MRRD–MEC-314-1543) with funding support from the Department of Science and Technology-Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOST-PCAARRD). We wish to thank the different Local Government Units (LGUs), the WWF-Philippines and our friends: S. F. Conales Jr., L. Ardines Jr., C. Maquiso, R. V. Ravina Jr., S. D. Villalva, J. A. Matillano, J. Genilan, N. Dieron, M. F. J. M. Oquendo, and B. A. Bonares, for their assistance during field surveys. We are also grateful for the comments and suggestions of the anonymous reviewers.