National Committee on Marine Sciences (NCMS)
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- Observations on a multi-seagrass meadow offshore of Negros Oriental, Republic of the PhilippinesTomasko, D. A.; Dawes, C. J.; Fortes, M. D.; Largo, D. B.; Alava, M. N. R. (Walter de Gruyter GmbH, 1993)Eight species of seagrasses were encountered in a multi-species meadow offshore of Negros Oriental, Republic of the Philippines: Halodule uninervis (Forssk.) Aschers., Halodule pinifolia (Miki) Den Hartog, Cymodocea rotundata Ehrenb. et Hempr. ex Aschers., Cymodocea serrulata (R. Br.) Aschers., Syringodium isoetifolium (Aschers.) Dandy, Thalassia hemprichii (Ehrenb.) Aschers., Enhalus acoroides (L./.) Royle, and Halophila ovalis (R. Br.) Hook./. A transect survey showed that five of the eight species were quite common, with cover estimates of individual species ranging from less than 10% to over 50%. Above- and below-ground biomass and leaf productivity data were collected for at least four species at each of three stations. Above-ground biomass for combined species ranged from 125 to 250g dw m~2, and below-ground biomass of combined species ranged from 264 to 828 g dw m~2. Areal production rates for combined species ranged between 4.78 to 9.38g dw m~2 d"1, with considerable inter-specific variation. High levels of protein and low levels of soluble carbohydrate were consistent with the rapid above-ground growth observed for all species, and also suggested high growth for below-ground portions of C. serrulata, H. uninervis, S. isoetifolium, and T. hemprichii. Epiphyte loads were low compared to sister species from other locations, perhaps due to rapid blade turnover rates (up to 7.8% day"1 for S. isoetifolium).
- Strong genetic structure and limited gene flow among populations of the tropical seagrass Thalassia hemprichii in the PhilippinesNakajima, Yuichi; Matsuki, Yu; Fortes, Miguel D.; Uy, Wilfredo H.; Campos, Wilfredo L.; Nadaoka, Kazuo; Lian, Chunlan (MDPI AG, 2023-02-05)Seagrasses are marine angiosperms, and seagrass beds maintain the species diversity of tropical and subtropical coastal ecosystems. For proper understanding, management and conservation of coastal ecosystems, it is essential to understand seagrass population dynamics. Population genetic studies can cover large geographic scales and contribute to a comprehensive understanding of reproductive dynamics and potential dispersal among locations. The clonal and genetic diversity and genetic connectivity of Thalassia hemprichii in the Philippines were estimated by a population genetics approach. The geographic scale of this study has a direct distance of approximately 1600 km. Although high clonal diversity was found in some sites (R = 0.07–1.00), both sexual and asexual reproduction generally maintains separate populations. Genetic diversity is not definitely correlated with latitude, and genetic differentiation is significant in all pairs of sites (FST = 0.026–0.744). Complex genetic structure was found in some regions, even at a fine geographic scale. The migration of fruits and seedlings was elucidated as an infrequent and stochastic event. These results suggest the necessity for the conservation of this species due to a deficiency in migrants from external regions.
- Seasonality of standing crop of a Sargassum (Fucales, Phaeophyta) bed in Bolinao, Pangasinan, PhilippinesTrono, Gavino C.; Lluisma, Arturo O. (Springer, 1990-09)The seasonality of standing crop of a Sargassum bed was investigated by conducting monthly sampling from February 1988 to July 1989. Environmental parameters of water movement, salinity, number of daytime minus tides, and water temperature were also measured. An intra-annual pattern of variation in standing crop of Sargassum crassifolium, S. cristaefolium, S. oligocystum, and S. polycystum was observed. Standing crop was generally lowest in February, March, April, or May, and highest in November through January. Sargassum accounted for about 35 to 85% of the monthly algal standing crop of the bed, and the observed variation in overall standing crop of the bed generally reflected the standing crop of Sargassum. The seasonality of the standing crops of the associated algal divisions also followed an annual cycle, but their maximum and minimum standing crops did not coincide with those of Sargassum. Individually, as well as collectively, the standing crops of the Sargassum spp. were poorly correlated with the environmental factors observed.
- Clonal propagation of Eucheuma denticulatum and Kappaphycus alvarezii for Philippine seaweed farmsDawes, C. J.; Trono, G. C.; Lluisma, A. O. (Springer, 1993-06)Technique improvement and cost reduction of branch culture, micropropagation, and callus production of carrageenan-yielding seaweeds Kappaphycus alvarezii and Eucheuma denticulatum is presented. Low cost branch culture is possible by enriching seawater with 0.1% coconut water with 1 mg l−1 indole-3-butyric acid for 24 h wk−1 or continuous culture with 0.01% Algafer, a Philippine fertilizer. Micropropagation of 0.5 cm explants had almost 100% new branch production demonstrating the viability of callus regenerated plants. The use of carrageenan as a media for callus production was not effective when compared to agar. Propagules of both species, transferred from the University of the Philippine Marine Science Institute (UPMSI) culture facility to the field, showed daily percent growth rates of 5 to 5.5% d−1 over 84 days. Based on the costs of the UPMSI laboratory, a culture facility in the seaweed farming area is estimated to cost about U. S. $22000 during the initial year and 58% less the second year.
- Water quality bioassays in two Bermudan harbours using the ciliate Euplotes vannus, in relation to tributyltin distributionSlabbing, A. R. D.; Soria, S.; Burt, G. R.; Cleary, J. J. (Elsevier, 1990-01)Laboratory cultures of the ciliate Euplotes vannus were used to bioassay water samples taken from the sea surface, 0.5 m and near bottom at stations along contamination gradients in Castle Harbour and Hamilton Harbour on Bermuda. Inhibition of population growth rate was used as an index of exposure to toxic contaminants. Significant differences in growth rates from near-bottom water samples taken at two stations in Castle Harbour were reflected in differing sediment concentrations of metals and petroleum hydrocarbons. Bioassays of four Hamilton Harbour samples indicated significant differences between control and contaminated sites when results from all three depths were pooled. Highest concentrations of tributyltin (⩽ 307 ng TBT·1−1) occurred in the surface microlayer, though measurements varied widely on the two sampling occasions. At 0.5 m, concentrations were much less variable and showed a steady decline from the head of Hamilton Harbour (41 ng TBT· 1−1) seawards to the control site (0.9 ng TBT · 1−1). While these concentrations are high enough to be toxic to some species, it is known from experimental work that TBT alone could not have accounted for the depression of ciliate growth rates in these bioassays.
- Nutrient limitation of Philippine seagrasses (Cape Bolinao, NW Philippines): in situ experimental evidenceAgawin, N. S. R.; Duarte, C. M.; Fortes, M. D. (Inter-Research Science Center, 1996)Nutrient limitation of Enhalus acoroides, Thalassia hemprichii and Cymodocea rotundata in 2 mixed seagrass beds (Silaqui and Lucero) in Cape Bolinao, NW Philippines was investigated through a 4 mo in situ nutrient addition experiment. Leaf growth of T. hemprichii and E. acoroides significantly increased by 40 to 100% and 160%, respectively, following fertilization. Leaf biomass of the 3 species also increased significantly by 60 to 240% following nutrient additions. The increased growth and biomass with fertilization was supported by enhanced photosynthetic activity, consequently by higher chlorophyll and nutrient concentrations in the photosynthetic tissues. These results demonstrated nutrient limitation of seagrass growth and photosynthetic performance at the 2 sites in Cape Bolinao. The nature and extent of nutrient limitation, however, varied between sites and among species. T. hemprichii and E. acoroides appeared to be mainly P deficient and N deficient, respectively (from significant increases in tissue P and N concentration following fertilization, respectively). The deficiency was moderate (26% of requirement) for T. hemprichii but substantial for E. acoroides (54% of requirement). Moreover, N and P deficiency was greater in Lucero than in Silaqui, consistent with the higher ambient nutrient concentration in the porewater and sediment nutrient and organic matter content in Silaqui. These results emphasize the importance of local differences in the factors controlling nutrient losses and gains in seagrass meadows and, more importantly, the importance of identifying the species-specific traits that generate the interspecific plasticity of nutrient status.
- Fisheries Administrative Order No. 236-5: Series of 2018. Extension of FAO 236-4 series of 2015 on the rules and regulations on the operations of purse seine and ring net vessels using Fish Aggregating Devices (FADS) locally known as Payaos during the FAD closure period as compatible measures to WCFPC CMM 2017-01.(Department of Agriculture, 2018-07-06)