Laboratory manipulation of Gracilariopsis bailinae Zhang et Xia (Gracilariales, Rhodophyta)
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Carpospore germination, carposporeling development and tetraspore formation were investigated in Gracilariopsis bailinae Zhang et Xia by manipulating photoperiod, photon flux density, temperature, salinity and nutrients. Laboratory-generated sporelings attained mean growth rate from 4.05 to 10.31% d-1 during the first week of incubation. Duncan s multiple range test (DMRT) showed that growth rates were significantly different (P < 0.05) between the treatment combinations and between weekly intervals. The optimal condition for growth of sporelings, irrespective of culture age, was attained at treatment combinations of 26°C, 11:13 (h. L:D) photoperiod, 100 µEm-2s-1 photon flux density (PFD), 25 µM NH4Cl: 2.5 µM K2HPO4 and 25ppt salinity followed by a treatment combination of 26°C, 11:13 (h. L:D) photoperiod, 100 µEm-2s-1 photon flux density (PFD), 50 µM NH4Cl: 5 µM K2HPO4 and 25 ppt salinity. For the first time in this species, tetraspore formation was induced in the laboratory. The tetrasporophyte produced many tetraspores in almost all branches of the thallus grown at 26°C, 11:13 (h. L:D) photoperiod, 100 µEm-2 s-1, 25 µM NH4Cl: 2.5 µM K2HPO4 and at 30 ppt salinity while those grown at lower light, higher nutrient level and higher salinity had fewer tetraspores. No tetraspores were formed at a higher temperature (30°C), longer photoperiod (13:11 h. L:D), and at 25 ppt salinity and the plants remained vegetative from 4 to 7 months. Logistic regression analysis showed that tetrasporangial induction was significantly affected by nutrients and salinity (P < 0.05).
CitationRabanal, S. F., Azanza, R., & Hurtado-Ponce, A. (1997). Laboratory manipulation of Gracilariopsis bailinae Zhang et Xia (Gracilariales, Rhodophyta).
PublisherWalter de Gruyter
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Effects of arachidonic acid supplementation on larval and survival and reproductive performance in rabbitfish, Siganus guttatus DR Chavez, HY Ogata, ES Garibay, HT Sollesta, KR Tibubos, H Furuita & A Suloma - In K Nakamura (Ed.), Sustainable Production Systems of Aquatic Animals in Brackish Mangrove Areas, 2007 - Japan International Research Center for Agricultural Sciences
Series: JIRCAS Working Report No. 56Fry of tropical marine fish needed for aquaculture still comes mostly from the wild. Thus, fry availability is a major constraint in the development and extension of aquaculture, especially in rural areas of developing regions. Although the mission of hatcheries is to provide a stable fry production and supply for farmers, fry production remains variable due to poor fecundity and low survival. For the last four years (2002-2005), SEAFDEC/AQD and JIRCAS have conducted the collaborative project that was aimed at developing advanced diets for improving egg production/quality (2002-2005) and larvae/fry quality (2004-2005) through dietary manipulation. Larval rearing tests: In 2005, larval rearing tests (4 trials with rotifers) were conducted to investigate the effects of enriched-live food (4treatments: low (CS) and high (DHAPS) HUFA with or without arachidonic acid supplementation) on survival and growth in rabbitfish Sigunus guttatus fry. Fry fed the rotifers enriched with a combination of DHAPS+5% ArA showed the best survival (44.4±4.5% for D17 fry in the 4th trial).Growth was not different among the treatments (CS, CS+5% ArA, DHAPS, DHPS+5% ArA). Broodstock tests: From March, 2005 to January,2006, a feeding test has been conducted to investigate the effects of dietary ArA supplementation (0% for diet 1, 0.3% for diet 2 and 0.6% for diet 3) on egg production and quality of wild-caught and hatchery-bled rabbitfish broodstock. The broodstock spawned 13 times for diet1 (six pairs), 14 times for diet 2 (five pairs) and 17 times for diet 3 (six pairs) during the period of May 2005 to January, 2006. The total numbers ofhatched-larvae were 3,818 x 103 for diet 1, 4,391 x 103 for diet 2 and 4,597 x 103 for diet 3. The % of normal larvae did not differ among the dietary treatments. Considering together with the results of mangrove red snapper (2003) and rabbitfish (2004), the optimum level of ArA incorporation appears to be between 0.5% and 0.7%. Judging from the results of fatty acid analysis, DHA and arachidonic acid should be supplemented to diets at the same time as to make DHA/arachidonic acid ratio appropriate. Thus, the present study clearly shows that dietary arachidonic acid supplementation is very promising for the development of fry production technologies in tropical areas.
Sustainable milkfish production in marine fish cages through strong government support and effective public-private partnerships: a case study from Panabo City Mariculture Park in Davao del Norte, Philippines FG Ayson, AM Ventura & EG de Jesus-Ayson - In W Miao & KK Lal (Eds.), Sustainable intensification of aquaculture in the Asia-Pacific region. Documentation of successful practices, 2016 - FAO Regional Office for Asia and the PacificThis case study presents the successful practice of sustainable intensification of milkfish aquaculture in marine fish cages under semi-intensive grow-out conditions in the Panabo City Mariculture Park (PCMP) in Davao del Norte, Philippines. Established in 2006, PCMP became operational through the promulgation of a City Ordinance declaring 1 075 hectares of municipal waters in Panabo City as a Mariculture Development Zone/Park. The operations of PCMP were so successful that in just five years it became the third largest among the 63 operational MPs in the Philippines during 2011, with 86 private investors-locators operating a total of 322 units of cages. At present, a total of 372 units of fish cages are operating in the mariculture park (MP). A combination of factors contributed to the successful operation of PCMP, but the success is usually attributed to the effective partnership between the government (both local and national) and the private sector. The Comprehensive MP City Ordinance that governs the PCMP is strictly implemented and includes, among others, the tenurial rights and access to locators. Regulations on distances between cages are strictly enforced and security measures in the total area are jointly undertaken by the government and the locators. The national government, through the Bureau of Fisheries and Aquatic Resources-National Mariculture Center (BFAR-NMC), provides technical support in all aspects from stocking to harvest during the production cycle. BFAR-NMC staff conduct regular periodic sampling of the stocks and compute feeding rates for the stocks which are implemented by the technicians/caretakers. Likewise, BFAR-NMC staff regularly monitor the water quality of the MP and the health status of the stocks. Since it became operational in 2006, the PCMP did not report a single incident of mass fish kill, which indicates that the technical guidelines of MP operations are strictly followed. Workers are trained and organized into groups by BFAR-NMC such as caretakers, cage framers, netters, harvesters, fish processors, and others, and actively participate in discussions related to MP operations to ensure protocols are properly followed. Harvests of stocks are done by skilled workers trained by BFAR-NMC, all done in the “Bagsakan Center” or fish landing area and are well-coordinated. The support facilities in the fish landing area are provided by both the local and national government and the PCMP Producers Association. The operators provide complete data for their operations to BFAR-NMC for record keeping. The strong partnership between the national government through BFAR-NMC, the local government unit, the investors, as well as the acceptance and support from the community for the PCMP is the hallmark of its success.
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