Journal Articles - UP - MSI
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- Advances in cultivation technology of commercial eucheumatoid species: A review with suggestions for future researchAsk, Erick I.; Azanza, Rhodora V. (Elsevier BV, 2002-04)An “advance” is defined as any technology that leads to an increase in production of Kappaphycus alvarezii (Doty) Doty, K. striatum Schmitz and Eucheuma denticulatum (Burman) Collins et Harvey (commercial eucheumatoid species) per unit time, effort, area and cost in more than one cultivation area. The present review has shown that no true advances have taken place in commercial eucheumatoid farming in over a decade. These species have remained the primary source of carrageenan through expansion of cultivation area and increase in the number of farmers since farmer productivity has not increased through time. Priority should be given to researches that could replace “tie–tie system” currently being used in the vegetative propagation of the crops and the possible use of spores/sporelings in cultivation as in other economic seaweeds. Multifactorial experiments considering nutrients, salinity and light especially, need to be done to meet seasonality problems in growth/production of the crops. Understanding and developing the capability to mitigate or eliminate pests, herbivores and diseases need to be addressed more closely. Strains should be developed through a continuous selection of wild varieties, breeding programs and genetic manipulation or transgenic production/development. Increasing the quality of extract through superior post-harvest handling and strain improvement should be achieved. Practical and effective quarantine procedures should be explored, publicized and utilized for introduction of crops to new areas.
- Chemical and gelling profile of ice-ice infected carrageenan from Kappaphycus striatum (Schmitz) Doty “sacol” strain (Solieriaceae, Gigartinales, Rhodophyta)Mendoza, Wilson G.; Montaño, Nemesio; Ganzon-Fortes, Edna T.; Villanueva, Ronald D. (Springer, 2002-10)The occurrence of ice-ice disease in farmed Kappaphycus spp. has tremendous implication on the carrageenan industry in the Philippines. To elucidate the effect of this disease on the carrageenan quality, the chemical profile of carrageenan extracted from healthy and diseased Kappaphycus striatum“sacol” strain, was investigated using 13C and 1H NMR, FT-IR and GPC methods of analysis. The native carrageenan extracts were composed predominantly of kappa carrageenan with trace amounts of iota and 6-O-methylated carrageenan. Structural evidence indicates depolymerization of carrageenan from the ice-ice infected portion of the thallus (whitish and soft part) lowered levels of iota and methyl constituents. This finding was correlated to its low number average molecular weight (30 kDa) value. Accordingly, appreciable decreases in carrageenan yield, gel strength and viscosity and increase in syneresis index were noted. On the other hand, archetype quality of kappa-carrageenan was observed from both healthy and uninfected portion of the diseased thalli.
- Achievements and lessons learned in restocking giant clams in the PhilippinesGomez, Edgardo D.; Mingoa-Licuanan, S. Suzanne (Elsevier BV, 2006-08)For almost 20 years, the Marine Science Institute (MSI), University of the Philippines, has been culturing giant clams to restore depleted populations of these large bivalves in the Philippines, and to promote giant clam farming as a sustainable livelihood. Restocking activities were done in collaboration with local groups by providing training in the culture and ocean rearing of giant clams, and by implementing a “users pay” approach. Initially, a variety of giant clam species was used but once F1 broodstock of Tridacna gigas were reared, restocking focused on this species due to its scarcity and fast rate of growth. About 20 000 T. gigas were placed on coral reefs. In addition, >50 000 clams (T. gigas, T. squamosa, T. derasa, T. crocea, T. maxima and Hippopus hippopus) were distributed through other means. Altogether, >40 sites throughout the Philippines received cultured giant clams. Grow-out trials to test the viability of supplying giant clams for the aquarium trade to create new sources of income were conducted successfully with a group of fishers in Bolinao, Pangasinan. However, this initiative encountered legal obstacles when the government regulatory agency prohibited the export of cultured clams, regarding this as a threat to the conservation of wild individuals. The long experience in culturing and restocking giant clams in the Philippines provides many lessons for other countries wishing to restore stocks of these large bivalves. Particular care needs to be given to selection of release sites, negotiations with participating groups to safeguard the released clams, adequate transfer of technology to collaborators, and transport of large clams from nursery areas to release sites.
- Elevated seawater temperatures affect embryonic and larval development in the giant clam Tridacna gigas (Cardiidae: Tridacninae)Enricuso, Odette B.; Conaco, Cecilia; Sayco, Sherry Lyn G.; Neo, Mei Lin; Cabaitan, Patrick (Oxford Academic, 2018-11-17)Giant clams are the largest bivalve molluscs and play a key role in coral reef ecosystems. Almost all species are considered endangered or vulnerable to extinction, thus requiring intervention through culturing and restocking. Although successful culture techniques have been developed, the responses of giant clam embryos and larvae to environmental factors, such as seawater temperature, are not yet fully understood. In this study, fertilization, development and survival of Tridacna gigas larvae were observed at low (28 °C), medium (30 °C) and high (33 °C) seawater temperatures. Fertilization success was not significantly different between the water temperatures tested. At 28 °C, ciliated gastrulae appeared first at 12 h postfertilization (hpf) and trochophore larvae at 24 hpf. In contrast, more rapid development was observed at 30 °C and 33 °C, with ciliated gastrulae first appearing at 9 hpf and trochophore larvae at 18 hpf. Veliger larvae were observed after 48 h at 28 °C and 30 °C. No veligers were observed at 33 °C, but a greater proportion of embryos and larvae exhibited developmental abnormalities at this temperature compared with the other treatments. Larval survival was lowest at 33 °C at the 12 and 24 h timepoints, although there was no longer a significant difference across treatments after 48 h. Furthermore, post-settlement survival of juveniles subjected to different seawater temperatures for 22 d starting at 8 d postfertilization (dpf) was lowest at 33 °C. These findings reveal that higher water temperatures promote rapid progression through early development, but result in lower overall survival as a consequence of abnormal development and reduced post-settlement survival.The authors acknowledge Julio Curiano and the staff of the Bolinao Marine Laboratory for assistance with experiments. This work was supported in part by the University of the Philippines Marine Science Institute; a grant from the National Geographic Society (ASIA-08-15) to PCC; a grant from the Department of Science and Technology Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (QMSR-MRRD-MEC-295-1449) to PCC and CC; and a Department of Science and Technology Science Education Institute graduate scholarship to OBE. MLN acknowledges the support of the National Research Foundation Singapore for research at the St John’s Island National Marine Laboratory.
- The community composition and production of phytoplankton in fish pens of Cape Bolinao, Pangasinan: A field studyYap, Leni G.; Azanza, Rhodora V.; Talaue-McManus, Liana (Elsevier BV, 2004-11)From 1995 up to the present, fish pens proliferated in the municipal waters of Bolinao, northern Philippines. Since then, fish kills and phytoplankton blooms have been recurrent. Have fishpens altered the phytoplankton community composition and production of these waters? The phytoplankton community in Cape Bolinao, Lingayen Gulf is typical of a tropical coastal area where diatoms alternate with dinoflagellates during the dry and wet seasons. In the nutrient-rich fish pens, phytoplankton in this study showed a lower diatom/dinoflagellate ratio and unusually high phytoplankton counts of 104 cells/l and even as high as 105 cells/l. Correlations between physico-chemical parameters, phytoplankton production and community composition were made in 2001. This paper tried to explain the occurrence of a Cylindrotheca closterium bloom (105 cells/l), during the dry season of the same year and a Prorocentrum minimum bloom (4.7 × 105 cells/l), which accompanied a massive fish kill during January 2002.
- k-Carrageenan gel as agent to sequester paralytic shellfish poisonCañete, Socrates Jose P.; Montaño, Marco Nemesio E. (Springer, 2002-12-01)The action of k-carrageenan gel to sequester paralytic shellfish poison (PSP) was tested and characterized. When an extract from a Philippine strain of Pyrodinium bahamense var. compressum was used as PSP solution, the PSP-sequestering property of k-carrageenan gel was found to be dependent on gel surface area, interaction time, and polysaccharide concentration. The interaction was also found to be affected by high concentrations of monovalent cations. The characteristics of k-carrageenan as a PSP-sequestering agent all point to cation exchange as its mechanism of action. It is also proposed that the polysaccharide gel can be utilized as an agent to alleviate PSP intoxication.
- Genetic structure of Linckia laevigata and Tridacna crocea populations in the Palawan shelf and shoal reefsJuinio-Meñez, M. A.; Magsino, R. M.; Ravago-Gotanco, R.; Yu, E. T. (Springer, 2003-02-11)Allozyme variation of 10 populations of Linckia laevigata at 8 polymorphic loci and 13 populations of Tridacna crocea at 6 polymorphic loci were analyzed to compare genetic variability and genetic affinities among reefs in Palawan, Philippines. Two to five populations were sampled from each of four regions: the shelf reefs in (1) northern Palawan and (2) southern Palawan and the offshore reefs in (3) the Kalayaan island group (KIG) in the South China Sea and (4) the Tubbataha shoals in the Sulu Sea. Heterozygosity was highest in populations of L. laevigata from the south shelf of Palawan and populations of T. crocea from the Tubbataha shoals of the Sulu Sea. The lowest heterozygosity estimates were from the reefs of the KIG in the South China Sea, for both species. Overall FST values for both species were significant, with an estimated average number of effective migrants per generation (NEM) of 4.85 (~5 individuals) for L. laevigata and 3.54 (~4 individuals) for T. crocea. Within-region comparisons showed NEM ranging from 6.29 to 92.34 for L. laevigata and from 3.40 to 6.30 for T. crocea. The higher gene flow among L. laevigata populations relative to T. crocea is consistent with the greater dispersal potential of the former species. Finer scale genetic structuring was evident in T. crocea populations. For both species, the Tubbataha reefs in the Sulu Sea have higher genetic affinity with the populations from the southern shelf of Palawan, while the reefs in the KIG had higher affinity with the northern Palawan shelf reefs. The north and south shelf populations have the least genetic affinity. Genetic patchiness among reefs within regions suggests the importance of small-scale physical factors that affect recruitment success in structuring populations in small island and shoal reef systems in Palawan.
- Comparison of coral growth and survival under enclosed, semi-natural conditions and in the fieldYap, Helen T.; Molina, Reverie Alvarez (Elsevier BV, 2003-07)Two closely related scleractinian coral species, Porites cylindrica and Porites rus, were transplanted to two different locations: the natural environment on the reef flat, and culture tanks on land. The use of tanks enabled the regulation of certain environmental factors, and, hence, the evaluation of specific responses of the corals to these factors. For both species, growth and survival were much better in the field than in the land-based tanks most probably due to unrestricted water circulation. Since the two species were subjected to identical experimental treatments, it was possible to distinguish inherent differences between them in terms of responses to external variables. Porites cylindrica was more susceptible than P. rus to predation by corallivores. Predators, as well as grazers, occurred in significant numbers in the field, but not in the land-based tanks. Porites rus, on the other hand, succumbed more readily to overgrowth by macroalgae which thrived in the culture tanks presumably because of significantly higher nutrient levels and the conspicuous absence of grazers. These results have broader ecological implications because of accelerated environmental changes taking place in present-day reefs due to human impact. Major examples are eutrophication and alterations in water circulation which frequently result in sub-optimal conditions for coral survival and growth.
- Water quality and holding capacity of intensive and semi-intensive milkfish (Chanos chanos) pondsSumagaysay-Chavoso, Neila S.; San Diego-McGlone, Ma. Lourdes (Elsevier BV, 2003-04)This study determined the holding capacity of semi-intensive and intensive milkfish ponds and water quality in relation to fish biomass and feed input. Six units of 1000 m2 brackishwater ponds were used, three ponds for intensive system (20,000 fish ha−1) and three for semi-intensive system (8000 fish ha−1). Average production was significantly higher in intensive pond (3652 kg ha−1) than in semi-intensive pond (1352 kg ha−1) after a desired marketable size of fish was reached. Highest concentrations in effluents (mg l−1) of rearing water measured every 2 weeks were 0.369 and 0.289 for chlorophyll a (chl a), 0.485 and 0.512 for PO4–P, 0.279 and 0.811 for TAN, 0.094 and 0.082 for NO2–N, and 14.040 and 8.649 for NO3–N, 216 and 142 for total suspended solids (TSS), 15.0 and 21.7 for biological oxygen demand (BOD), in intensive and semi-intensive ponds, respectively. Lowest morning dissolved oxygen (DO) in intensive pond was 2.2 mg l−1, and did not decrease further because of aeration. In unaerated, semi-intensive pond, morning DO ranged from 1.3 to 5.0 mg l−1 but occasionally went below 1.0 mg l−1 resulting to fish mortalities at biomass of 835, 1206, and 1489 kg ha−1. Levels of NO3–N and dissolved inorganic N are linear functions of fish biomass or feed input in all systems (P<0.05). The buildup of nutrients is more pronounced at biomass of 1610 kg ha−1 and above while nutrient transformation (conversion of PO4–P or TAN to phytoplankton or vice versa) is apparent at biomass below 1419 kg ha−1. The holding capacity of unaerated, semi-intensive pond is below 1348 kg ha−1 or 54 kg feed ha−1 day−1 based on DO concentration of less than 1.0 mg l−1. However, the holding capacity can be lower than 835 kg ha−1 or 33 kg feed ha−1 day−1 during very calm weather or during rainy days when water column is stratified. Based on the results of regression analysis, the holding capacity of intensive pond should be set below 5107 kg ha−1 or 110 kg feed ha−1 day−1 so as not to exceed the acceptable levels for water quality variables in effluent waters.
- Spatial structure of demersal fish assemblages in South and Southeast Asia and implications for fisheries managementGarces, L. R.; Stobutzki, I.; Alias, M.; Campos, W.; Koongchai, N.; Lachica-Alino, L.; Mustafa, G.; Nurhakim, S.; Srinath, M.; Silvestre, G. (Elsevier BV, 2006-05)We provide a review of the assemblage structure of demersal fish resources in four South and Southeast Asian countries. Multivariate techniques (classification and ordination analysis) were used to analyze scientific trawl survey data from a collaborative project in the region. Analyses covered major coastal fishing areas in Bangladesh, Indonesia, Malaysia, and the Philippines. This represents the first such assessment of fish assemblages for the region using a standard analysis framework. Results indicate that spatial patterns of demersal assemblages are influenced by depth. However, other environmental factors such as salinity and substrate type also appear important. Critical fisheries management implications of the observed assemblage patterns are discussed, particularly in terms of the existing spatial management zones. Existing management zones are based on distance from shore and were found to be largely inconsistent with the assemblage patterns observed. If management is to be effective it must be structured to take into account the underlying pattern of the fish assemblages.