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    • Article

      Microalgal paste production of the diatom Chaetoceros calcitrans using electrolytic flocculation method at optimum culture conditions 

      MR de la Peña, AV Franco, HP Igcasan Jr., MDGN Arnaldo, RM Piloton, SS Garibay & VT Balinas - Aquaculture International, 2018 - Springer Verlag
      The optimum culture conditions of the local strain Chaetoceros calcitrans were determined to improve biomass and reduce cost of production. Under outdoor culture conditions, higher cell density was attained when the cultures were enriched with Tungkang Marine Research Laboratory (TMRL) medium composed of cheap technical grade reagents and cultured at 25 g L−1 salinity. The cultures were lighted with two 40 W cool-white GE fluorescent tubes (24–35 μmol photon m−2 s−1). Using semi-continuous culture system under established optimum culture conditions, C. calcitrans can be re-cultured thrice and concentrated at each culture cycle using electrolytic flocculation method to produce 4.6 kg m−3 of diatom paste. The viability of concentrated C. calcitrans after 3 months of storage was comparable to live diatom cells. Simple preservation technique by low-temperature storage is convenient for storing algal concentrates for use as starter cultures and for feeding invertebrates. The paste costs USD 8.24 kg−1 inclusive of the assets and flocculation materials for culturing and harvesting the diatom, respectively. This study established the suitable conditions for mass culture of C. calcitrans and produced concentrated diatoms in paste form that is readily available for aquaculture hatcheries at a lower cost.
    • Book chapter

      Transplantation, hatchery, and grow-out of window-pane oyster Placuna placenta in Guimaras and Iloilo 

      SS Garibay, SN Golez & AS Unggui - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
      The windowpane oyster Placuna placenta (local name kapis) used to be harvested in large quantities and support a shellcraft industry in the Philippines, particularly in Panay Island. But the fishery and the industry declined markedly by the 1990s. Studies were conducted to transplant kapis and also to develop hatchery techniques for it in an effort to counter the population depletion. Kapis with average shell heights of 7 cm and 10 cm were transplanted from Roxas City in northern Panay Island and from Oton, Iloilo in southern Panay to Taklong Island in Guimaras during the rainy season (July–November) and the dry season (February–June). Survival of the transplants was higher during the dry season (57–60%) than during the rains (35–48%). Sexually mature kapis 10 cm in shell height were induced to spawn by temperature manipulation, water level manipulation, and use of ultravioletirradiated sea water. Spawning was successfully induced by raising the water temperature to 29±0.5oC. Eggs measured 45 μm on average, and fecundity was 5,000–10,000 per female. Kapis larvae were reared on a combination of the microalgae Isochrysis galbana, Tetraselmis sp., and Chaetoceros calcitrans, maintained at a density of 100,000 cells/ml. Three water treatment schemes were tested for larval rearing: chlorination, ultraviolet irradiation, and filtration (control). Larvae survived to the umbo veliger stage (180 μm, day 10) in chlorinated sea water whereas mass mortality occurred at the straight-hinge stage (days 4–) in both UV-treated and filtered sea water.