National Committee on Marine Sciences (NCMS)

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Fisheries Administrative Order No. 1. Organization and functions of the Bureau of Fisheries.
(Department of Agriculture and Natural Resources, 1947-07-01)
Spontaneous maturation and spawning of milkfish in floating net cages
Marte, Clarissa L.; Lacanilao, Flor (Elsevier, 1986-04)
Milkfish (Chanos chanos Forsskal) reared from wild-caught fry and from hatchery-bred fry matured at 3.5–5.5 years (2.3–4.9 kg). Maturation and spawning of the hatcherybred fish marks the first time the milkfish life-cycle has been completed in captivity. Milkfish at various stages of gonadal development were obtained in July–October 1980 and March–June 1981 derived from wild-caught fry, and in February–June 1983 from the hatchery-bred fish. The fish were held in floating net cages 9 m and 10 m diameter by 3 m deep, located in 7 m deep water off Igang, Guimaras Island, Philippines. Annual ranges of temperature and salinity were 25–33°C and 25–38 ppt, respectively. The fish were fed commercial feed pellet (42% protein) at 1.5–2% of body weight twice daily. Sexual maturation occurred during the natural breeding season of wild milkfish in the nearby waters. Gonadosomatic index (GSI) of mature males was 0.32–3.95 (wild-caught, 0.32–3.95; hatchery-bred, 1.71–3.85). For mature females it was 1.24–8.12 (wildcaught, 1.56–7.62; hatchery-bred, 1.24–8.12). Two spawnings were recorded in August 1980 and eight in May–July 1981 from the broodstock derived from wild-caught fry, with 342–6293 eggs collected from each spawning, while 14 spawnings were observed in May–June 1983 from the hatchery-bred fish, with 770–114 000 eggs collected. The time of spawning was between 23.00 and 02.00 h. Fertilization rate was 55–99% for the broodstock from wild-caught fry and 47–100% for the hatchery-bred fish. Hatch rate varied from 9 to 80%. Factors affecting spontaneous maturation, spawning and rematuration are discussed. Although slight improvements in egg collection were obtained, further innovations in egg collecting techniques will have to be developed. The results indicate the potential for hatchery production of milkfish fry from captive broodstock and for restocking of waters deprived of naturally occurring fry.
Electrophoretic evidence for extensive hybrid gene introgression into commercial Oreochromis niloticus (L.) stocks in the Philippines
Macaranas, J. M.; Taniguchi, N.; Pante, M. J. R.; Capili, J. B.; Pullin, R. S. V. (Hindawi Limited, 1986-10)
The usefulness of isozyme and protein markers in identifying tilapia species and their hybrids is demonstrated. Genetic characterization of Oreochromis niloticus populations from commercial farms, experimental stations, and government hatcheries in Luzon, Visayas and Mindanao in the Philippines indicates well-established introgression with O. mossambicus. Genetic differentiation of the O. niloticus stocks, measured by Nei's genetic distance, was highly correlated with O. mossambicus gene content. The implications of these results for tilapia genetic improvement are discussed.
Indo-West Pacific affinities of Philippine seagrasses
Fortes, M. D. (Walter de Gruyter, 1988)
A dendrograph was developed to depict the mutual relationships among 27 Indo-Pacific countries with similar seagrass floras. Hierarchical (cluster) analysis of the resulting affinities provides strong evidence that the countries could be partitioned into seven discrete provinces. The genus Halophila represents a major connection between most of these provinces, strongly influencing the clustering of the Seagrasses. The degree of species overlap (9.5 — 46.2%) between Province A (where Philippines belongs) and Province G (Western, Southern, and Southeastern portions of Australia) favors vicariance as an explanation. The separation of Kampuchea as a discrete unit within Province A appears to be an artifact of collection rather than a reflection of the true floral affinities in the region. The lack of sufficient basic floristic information remains as the most serious limitation in any attempt to describe the phytogeographic affinities of seagrasses in the Indo-Pacific region.
Growth rates and primary production of Enhalus acoroides (L.f.) royle from Lag-it, North Bais Bay, the Philippines
Estacion, Janet S.; Fortes, Miguel D. (Elsevier, 1988-01)
The growth rates and primary production of the leaves of Enhalus acoroides (L.f.) Royle at Lag-it, North Bais Bay, The Philippines, were studied from August 1982 to August 1983. Randomized complete block design showed that both rates are considerably influenced by the composite effect of spatial and temporal factors. Similarly, both are markedly bimodal. Mean growth rate was 0.93 cm day−1, with peaks in September–October and May, with lowest values in November–January. Mean production was 0.92 g C m−2 day−1, with peaks in October and March–May (Station 2) and December (Station 1) and lowest values in December (Station 2) and in June (Station 1). Growth rates significantly increased with a decrease in the percent of time the seagrass beds were exposed to air and sun in the daytime (r=−0.69), while it increased with the number of daylight hours (r=0.72). Production showed no significant correlation with either factor. Mean turnover time for the seagrass was 67 days, producing 5.5 crops annually.
Temperature-influenced infection rates in the Chondrus crispus-Petersenia pollagaster pathosystem: A regression analysis
Molina, F. I.; Hughes, G. C.; Craigie, J. S. (Springer, 1988-03)
Cross-infection experiments were performed to determine the influence of temperature on infection rate in the Chondrus crispus Stackhouse-Petersenia pollagaster (Petersen) Sparrow pathosystem. C. crispus thalli were collected at Pubnico Harbor, Nova Scotia, Canada in the fall of 1981 to 1984. Infective zoospores were used to inoculate healthy thalli at five different temperatures. The highest infection rate was obtained at 20°C, while significantly lower rates were obtained at temperature extremes. The parasite's life cycle, consisting of infection of healthy thalli, endobiotic development, and release of zoospores, was completed in 48 to 72 h at 15° to 20°C.
Fishing mortality rates of giant clams (Family Tridacnidae) from the Sulu Archipelago and Southern Palawan, Philippines
Villanoy, Cesar L.; Juinio, Antoinette R.; Meñez, Lambert Anthony (Springer, 1988-05)
Average size frequency distributions of Tridacna squamosa, T. gigas, Hippopus hippopus and H. porcellanus harvested from the Sulu Archipelago and Southern Palawan areas from 1978–1985 were derived from export records and a warehouse inventory of giant clam shells. Average species mortality rates (Z) were estimated and were used to approximate average fishing mortality rates (F) over the period 1978–1985. Crude estimates of exploitation rates (F/Z) indicate that populations of these species are already overexploited. These findings have serious implications in view of the fact that the Sulu Archipelago and Southern Palawan are thought to be the last strongholds of giant clams in Philippine waters.
Notes on the induced spawning and larval rearing of the Asian moon scallop, Amusium pleuronectes (Linné), in the laboratory
Belda, C. A.; Del Norte, A. G. C. (Elsevier, 1988-08)
Sexual and chemical stimulations were effective in inducing the scallop, Amusium pleuronectes (Linné), to spawn sperm only, whereas thermal stimulation was not at all successful. Chemical stimulation consisted of serotonin injections into the ripe gonads. Fertilizable eggs were obtained by stripping gametes from the ovaries. Cleavage of zygotes (72.4 μm mean diameter) occured 1 h after fertilization. Trochophores (58.9–111.2 μm in length) and straight-hinge veligers or D-veligers (80.0–130.2 μm) were observed in less than 24 h. Five days after fertilization, the umbone stage (101.6–169.1 μm) was reached. Crawling pediveligers (174.0–250.0 μm) appeared after 9 days. Seawater in the culture vessels was changed 24 h after fertilization and every other day thereafter. The larvae were fed on Isochrysis galbana (Tahitian strain) at an initial concentration of 30 cells/gml.
Aspects of the growth, recruitment, mortality and reproduction of the scallop Amusium pleuronectes (Linné) in the Lingayen Gulf, Philippines
Del Norte, A. G. C. (Informa UK Limited, 1988-11)
Growth, recruitment, mortality and reproduction were investigated in the Asian moon scallop, Amusium pleuronectes (Linne) from the Lingayen Gulf, Philippines. Allometric relationships were defined by comparing different shell dimensions, as well as body weight proportions including total weight with shell, visceral weight, adductor muscle weight and gonad weight. Use of the von Bertalanffy-based ELEFAN I program yielded estimates of growth parameters equivalent to H ∞ = 106Dimshell height and K = 0.92 per year, with approximate longevity for the species of about 2 years. Recruitment, as derived using the ELEFAN II program, occurred throughout the year, but showed a pattern consisting of one major and one minor pulse separated by an 8- and 4-months interval. Fishing mortality (F = 5.3) was higher than natural mortality (M = 1.9). Spawning occurred throughout the year, with one major peak in February and one minor peak between July and September, thereby providing some biological basis to the recruitment pattern indicated. Protandry and size at sexual maturity (54 mm) in the species were confirmed.
Status of giant clam resources of the Philippines
Juinio, Marie Antoinette R.; Meñez, Lambert Anthony B.; Villanoy, Cesar L.; Gomez, Edgardo D. (Oxford University Press (OUP), 1989-11-01)
Field surveys were conducted to determine distribution and abundance of giant dam resources in the Philippines. All seven known species of giant clams were recorded with Tridacna crocea, T. maxima and T. squamosa occurring the most frequently. The larger species T. derasa, T. gigas, Hippopus hippopus and H. porcellanus were relatively rare. The reduction of giant dam stocks in the Philippines is due to the uncontrolled exploitation of this resource which is primarily gathered for shellcraft and as supplementary diet in coastal villages.
The farmed Euchema species in Danajon Reef, Philippines: Vegetative and reproductive structures
Azanza-Corrales, R. (Springer, 1990-03)
As part of the information needed for applied research on hybridization of these economically important species, the vegetative and reproductive structures of Eucheuma denticulatum (Burman) Collins and Hervey, and Eucheuma alvarezii Doty being farmed in Danajon Reef, were studied. All cultured ‘strains’ suspected to have developed from original stocks apparently introduced into the area about twelve years ago were sampled monthly from February 1987 to November 1988. Analyses of fresh free-hand and plastic embedded sections revealed the sexual (male, female) and asexual (tetrasporic) structures in E. alvarezii var.tambalang Doty and the absence of the female in E. denticulatum, indicating the suitability of the former species for future manipulative experiments.
The farmed Eucheuma species (Gigartinales, Rhodophyta) in Danajon Reef, Philippines: Carrageenan properties
Azanza-Corrales, R.; Sa-a, P. (Springer, 1990-09)
Six cultured ‘strains’ of Eucheuma denticulatum and E. alvarezii, from which stocks can be selected for the development of a Eucheuma ‘seedling bank’, were tested for their carrageenan quality from June to November 1988. Percent yield of all the varieties taken together was apparently higher in June, becoming lower in November (regression, r −0.785, probability, p ⩽ 0.001). Stepwise regression analysis was done to determine the existence of any relationship between any of the following parameters: gel strength, viscosity, sulfate content, month of sampling, and yield, whether taken individually or in combination. Results show variations of the yield with the month of sampling. ANOVA was performed to test whether there are differences in sulfate levels, gel strength, and viscosity between the Eucheuma alvarezii morphotypes. There was no significant difference between the green and the brown types.
Influence of Bass Strait water on the Tasman Sea thermocline
Villanoy, C. L.; Tomczak, M. (CSIRO Publishing, 1991)
Volumetric analysis of the Tasman Sea Central Water for different temperatures and salinities was used to determine the degree of influence of the seasonal outflow from Bass Strait on the observed strong positive anomalies in the Tasman Sea thermocline. The absence of a systematic decrease of salinity and Bass Strait Water content away from the coast suggests that the observed high-salinity anomalies are not entirely manifestations of Bass Strait Water alone and that some local processes may be involved in modifying the water properties. It is suggested that the seasonal Bass Strait Water intrusions may act as a trigger to overturn the environment, entraining high-salinity water from the upper layers by double-diffusive convection.
Seagrass-mangrove ecosystems management: A key to marine coastal conservation in the ASEAN region
Fortes, Miguel D. (Elsevier, 1991-01)
Seagrass beds and mangrove forests are intimately linked by functional interactive processes which are as yet little understood. These high-order interactions form a major basis which justifies an integrated management scheme for the two ecosystems. However, while dominating enclosed coastal areas in the ASEAN region, seagrass and mangrove habitats are being degraded and destroyed at an alarming rate, raising serious doubt on their capacity for biological sustainability and normal recovery within this generation. An integrated approach towards seagrass and mangrove ecosystems management in the ASEAN region is discussed within a framework of known ecological principles. Recommendations are made for the conservation and sustainable use of the ecosystems and their resources.
Benthic energy dynamics in a southern Baltic ecosystem
Yap, H. T. (Springer, 1991-10)
Benthic components and metabolic activity at two stations in the Darss-Zingst estuary (eastern German Baltic coast) were investigated over a seasonal cycle from April 1985 to August 1986. As has been established for temperate and boreal ecosystems, peaks in the biomass of benthic microphytes occurred in the spring and late autumn to winter, presumably caused by settling phytoplankton blooms. Metabolic activity of the benthos did not increase with rising ambient temperatures. Rather, the highest values of oxygen consumption were recorded during the cooler months (spring and winter), when increased numbers of organisms were also observed. This may be a response to a greater food supply to the sediment in the form of settling phytoplankton during these times of year.
Reproduction in Eucheuma denticulatum (Burman) Collins and Hervey and Kappaphycus alvarezii (Doty) Doty farmed in Danajon Reef, Philippines
Azanza-Corrales, Rhodora; Mamauag, Samuel S.; Alfiler, E.; Orolfo, M. J. (Elsevier, 1992-04)
Occurrence of reproductive structures in seven forms belonging to two species of carrageenophytes, Eucheuma denticulatum and Kappaphycus alvarezii was determined at a farming site at Danajon Reef, Northern Bohol, Philippines during 1987 and 1988. Reproductive plants of these forms were encountered throughout the study period although not all three structures (asexual or tetrasporic form and sexual male and female forms) were represented in each form. For K. alvarezii forms, taking the ‘browns’ (EAB1 and EAB2) and the ‘greens’ (EAG1 and EAG2) collectively, male and female reproductive structures were found throughout the year but no tetrasporic thalli were encountered. Only male and tetrasporic structures were observed for E. denticulatum (EDB and EDG) while the ‘sacul type’ ( EAG3 ) had both structures present throughout the study period. Analysis of variance revealed significant difference (P < 0.05) in the frequencies of reproductive structures of each form.
Genetic structure of giant clam (Tridacna derasa) populations from reefs in the Indo-Pacific
Macaranas, J. M.; Ablan, C. A.; Pante, M. J. R.; Benzie, J. A. H.; Williams, S. T. (Springer, 1992-06)
Large genetic differences were observed among the Great Barrier Reef (GBR), Fiji and Philippine populations of Tridacna derasa (Roding) sampled in 1989 and 1990 (Nei's unbiased genetic distance, D,=0.137 to 0.341). This result contrasted strongly with the low genetic distance (D=0.032) reported previously for the giant clam T. maxima over similar geographical scales. No significant genetic differentiation was observed among most populations from the GBR (mean D=0.007), consistent with the high gene exchange expected in this highly connected reef system. However, significant differentiation resulting from differences in the frequencies of less common alleles between the North-Central GBR and South GBR (Swain region) were observed. Historical isolation of blocks of the Central Indo-West Pacific from the GBR and present-day restrictions to gene exchange between the GBR, Fiji and the Philippines as a result of oceanographic current patterns, were thought to be responsible for the high degree of genetic differentiation of T. derasa populations. The relevance of these findings to clam mariculture and reef restocking are briefly discussed.
Passive greenhouse heating, recirculation, and nutrient addition for nursery phase Tridacna gigas: Growth boost during winter months
Braley, Richard D.; Sutton, David; Mingoa, S. Suzanne M.; Southgate, Paul C. (Elsevier, 1992-11)
The impetus for this study was winter-related mortality of juvenile Tridacna gigas along Australia's Great Barrier Reef. Heating nursery tank water by passive solar heating in a greenhouse and the addition of dissolved inorganic nitrogen (DIN) was assessed for effect on the growth and survival of cultured juvenile clams. Two age classes of T. gigas were used, with means of 1.2 cm and 17.0 cm shell length. Treatments consisted of nutrient-spikes of 20 μ M and 40 μ M ammonium chloride daily or on alternate days, plus s spike of 2.3 μ M phosphate once per week vs. controls without nutrient addition. Three rearing systems were used: (1) recirculating water enclosed in a greenhouse; (2) flow-through water enclosed in a greenhouse; (3) flow-through water with ambient conditions. In the older clams growth in weight was best in system 2, while growth in shell length (SL) was best in system 1, and DIN treatments significantly increased growth compared with controls. In the younger clams, growth in SL was best in system 1. DIN treatments produced significantly greater growth than controls, but there was no difference between 20-μ M and 40-μ M treatments. Survival was 100% for larger clams but for smaller clams mean survival was highest overall in system 1, while 20-μ M DIN treatments within systems produced the best overall survival. The highest levels of DIN in the nursery tanks were found in the 40-μ M DIN treatments, particularly in system 1. The wet tissue weight/shell length ratio for 40-μ M DIN treatments was highest in system 1 and decreased in systems 2 and 3, while controls were similar. Dry shell weight/shell length was highest in the 40-μ M DIN treatment over the control in system 1 only. The zooxanthellae index (no. of algal cells/g clam) was significantly higher in the 40-μ M DIN treatment than in the control in all three systems. Biochemical analysis of whole animals showed higher carbohydrate content in system 2 and in treatments receiving 20 μ M DIN. Tissue protein content did not differ significantly between systems but increased with increasing nutrient concentration. Lipid content was highest in system 1 and decreased with increasing nutrient concentration. Tissue water content of clams at the 20-μ M DIN level was lower than clams in other treatments, indicating superior condition. The combination of passive solar heating, recirculated water, and nutrient addition for the giant clam land nursery phase opens possibilities for culture of this tropical bivalve in subtropical zones or in the tropics distant from the ocean.
The role of epiphytic periphyton and macroinvertebrate grazers in the trophic flux of a tropical seagrass community
Klumpp, D.W.; Salita-Espinosa, J. S.; Fortes, M. D. (Elsevier, 1992-11)
Biomass and production of epiphytic periphyton, and the abundance, distribution and grazing rate of epifauna were measured in tropical seagrass beds in the Philippines. Periphyton comprised mainly detritus, diatoms and filamentous algae (Polysiphonia sp. 1, Centroceras clavulatum (C. Agardh) Montagne, Ceramium gracillimum Harvey and Cladophora sp.). Mean biomass of periphyton was 0.16 mg ash-free dry weight (AFDW) cm−2 frond of Enhalus acoroides (L.f.) Royle and 0.24 mg AFDW cm−2 frond of Cymodocea serrulata (R. Br.) Aschers. and Magnus. Total periphyton biomass per unit area (m2) of seagrass bed varied between habitats because of differing densities of seagrass, and ranged from 598 to 1061 mg AFDW or (24–646 mg C). Maximum (midday, summer) in situ rates of photosynthesis and respiration by epiphytes colonising artificial seagrass material averaged 11.6 μg O2 cm−2 h−1 and 2.0 μg O2 cm−2 h−1, respectively. Daily net productivity was 14 μg C cm−2 frond. Productivity of epiphytes per area of seagrass bed varied with site (36–77 mg C m−2 day−1). Relative to biomass, these data show that epiphytes are highly productive, with turnover times of 6–8 days, compared with known values of 30–100 + days for tropical seagrass fronds. The epifaunal grazer community was dominated by a few species of gastropod molluscs (especially Strombus mutabilis Swainson and Cerithium tenellum (Sowerby)). Within habitats, numbers of grazers on particular seagrass species were directly related to their available surface. Three groups of grazers were identified: those occurring on fronds day and night (e.g. S. mutabilis); those foraging over sediment during the day and fronds at night (e.g. Cerithium tenellum); those mainly confined to sediments (e.g. Strombus urceus L.). All epifaunal grazers exhibited upward movement into the seagrass canopy at night. Grazing was non-selective, removing the periphyton, except for the unutilised encrusting coralline algae, in proportion to abundance. Epifaunal grazers consumed between 20 and 62% of periphyton net production and, as in temperate systems, must therefore play a major role in the trophic flux of this tropical seagrass community.
Five new sesquiterpenes from the red alga Laurencia flexilis
de Nys, Rocky; Wright, Anthony D.; König, Gabriele M.; Sticher, Otto; Alino, Perry M. (American Chemical Society (ACS), 1993-06)
The red alga Laurencia flexilis, collected from Philippine waters, yielded five new sesquiterpenoid metabolites, 3,4-epoxypalisadin A [1], 5B-acetoxypalisadin A [2], 12-bromopalisadin B [3], palisading C [4], and 5B-hydroxypalisadin B [5]. The known metabolites 6-10 were also isolated The unambiguous assignments of H- and C-nmr spectral data for compounds 7 and 8 are reported for the first time.