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00. Ocean Decade - Philippines

Permanent URI for this communityhttps://repository.unesco.gov.ph/handle/123456789/7

The UNACOM Online and Digital Enabling Library and Index is developed to support the alignment of research, investments, and community initiatives toward contributing to a well-functioning, productive, resilient, sustainable, and inspiring ocean. The goal is to enable the government, partner agencies, and UNESCO to develop more robust Science-Informed Policies and facilitate a stronger Science-Policy Interface through the gathered data, information, and knowledge related to the Ocean Decade in the Philippines.

Particularly, it aims to:
  • Gather and index all publications, reports, policies, laws, legislations, articles, and other documents of the Philippine National Committee on Marine Sciences (NCMS) related to the Ocean Decade.
  • Disseminate and promote these publications, reports, policies, and other documents on the initiatives and actions to address the Ocean Decade challenges.

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1992 - 19963

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Author: search.filters.author.Fortes, M. D.Scientific name: search.filters.scientificname.Enhalus acoroides

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    Observations on a multi-seagrass meadow offshore of Negros Oriental, Republic of the Philippines
    Tomasko, 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).
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    Nutrient limitation of Philippine seagrasses (Cape Bolinao, NW Philippines): in situ experimental evidence
    Agawin, 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.
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    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.