Challenge 06: Increase community resilience to ocean hazards
Permanent URI for this collectionhttps://repository.unesco.gov.ph/handle/123456789/25
Ocean Decade
Challenge 06:
Increase community resilience to ocean hazards
Enhance multi-hazard early warning services for all geophysical, ecological, biological, weather, climate and anthropogenic related ocean and coastal hazards, and mainstream community preparedness and resilience.
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- Molecular phylogeny of three unarmored dinoflagellates from Masinloc Bay, Zambales, Central Luzon, with a description of the morphology of Gymnodinium catenatum H.W.GrahamBenico, Garry; Azanza, Rhodora (Science and Technology Information Institute, 2021-10-27)Unambiguous identification of unarmored dinoflagellates is important in distinguishing toxic from non-toxic species occurring in the coastal waters of the Philippines. In this study, molecular phylogeny inferred from rDNA sequences of Gymnodinium catenatum, Gymnodinium impudicum, and Akashiwo sanguinea-collected from Masinloc Bay, Zambales, Central Luzon-is reported for the first time. Morphology of G. catenatum was critically examined using light and confocal laser scanning microscopy. The three unarmored dinoflagellates were identified as G. catenatum, G. impudicum, and A. sanguinea based on their phylogenetic positions inferred from LSU and SSU rDNA. Both G. catenatum and G. impudicum grouped in a well-supported clade of Gymnodinium sensu stricto, which includes other genera of unarmored dinoflagellates, confirming the polyphyly of the clade. Akashiwo sanguinea separated into four subclades, which is similar to previous reports-with our strain grouping with sequences from Malaysia, Singapore, and China. Cellular characteristics of our G. catenatum are congruent with earlier reports particularly its long chain-forming habit (up to 64 cells) and large cell size (44.6-63.3 µm long). Our result is the first verified record of G. impudicum and A. sanguinea in the Philippines, and the first record of G. catenatum as another highly toxic dinoflagellate species occurring in Masinloc Bay.
- Characterization of Alexandrium tamutum (Dinophyceae) isolated from Philippine waters, with the rare detection of paralytic shellfish toxinBenico, Garry; Azanza, Rhodora (Association of Systematic Biologists of the Philippines, 2022-04-01)Alexandrium tamutum M.Montressor, A.Beran & U.John is a non-toxic, bloom-forming dinoflagellate species commonly reported in temperate waters. In this study, 8 cultures of A. tamutum established from Bolinao Channel and Manila Bay, Philippines were characterized in terms of their morphology, phylogeny and toxicity. Cells were roundish, measuring 25.5 –29.84 µm long and 26.2–28.45 µm wide. The nucleus is equatorially elongated and located at the center of the cell. The chloroplasts are numerous, golden brown in color and radially arranged. Thecal tabulation is typical of Alexandrium: APC, 4', 6'', 6c, 6s, 5''', 2''''. Shape of the taxonomically informative thecal plates such as sixth precingular plate (6'') and posterior sulcal plate (sp) was similar to A. tamutum, which confirms the species identity. However, the presence of anterior and posterior attachment pores observed in our cultured isolates is the first case in this species. Molecular phylogeny inferred from LSU rDNA and ITS supports our identification by forming a well-supported clade composed of A. tamutum strains from other geographic regions. HPLC analysis showed that A. tamutum is generally non-toxic except for strain ATC9 which has low amount of decarbamoylsaxitoxin (dcSTX), resulting to a toxicity of 0.07 fmole STX eq per cell. The present study reports the first verified occurrence of Philippine A. tamutum with reliable morphological and molecular information, including the first record in Manila Bay and first detection of PST in one strain at a certain culture period.We acknowledge the Department of Science and Technology Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOST PCAARRD) and the University of the Philippines-The Marine Science Institute (UP-MSI) for the funding support. We are grateful for the assistance of Joshua Vacarizas, Keith Pinto and Jenelyn Mendoza for the molecular and toxicity analyses of the cultures. We also acknowledge Estrelita Flores, Emelita Eugenio and Jayson Orpeza for their assistance during the fieldwork and other logistical support.
- Taxonomy and toxin production of Gambierdiscus carpenteri (Dinophyceae) in a tropical marine ecosystem: The first record from the PhilippinesVacarizas, Joshua; Benico, Garry; Austero, Nero; Azanza, Rhodora (Elsevier, 2018-12)Morphological and phylogenetic analysis showed that the Gambierdiscus isolate from Bolinao, Philippines belongs to the species of G. carpenteri. It was morphologically more similar to the Merimbula strain than the subtropical Florida Keys strain. Growth and toxin production were also investigated at varying levels of temperature, salinity, and irradiance. Gambierdiscus are known to grow favorably in a low light environment. However, this study showed high growth rates of G. carpenteri even at high irradiance levels. Generally, cells produced more toxins at lower treatment levels. Highest cellular toxin content recorded was 7.48 ± 0.49 pg Pbtx eq/cell at culture conditions of 25 °C, 100 μmol photons m−2 s−1, and salinity of 26. Growth rate and toxin production data suggest that cells produced more toxins during the slowest growth at certain range of treatments. This information gives insight into how changes in environmental conditions may affect toxin production and growth of G. carpenteri.