Journal Articles - UP - MSI
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- Nutrient limitation of the tropical seagrass Enhalus acoroides (L.) Royle in Cape Bolinao, NW PhilippinesTerrados, Jorge; Agawin, N.; Duarte, Carlos M.; Fortes, Miguel D.; Kamp-Nielsen, L.; Borum, J. (Elsevier BV, 1999-11)Experimental additions of nutrients to the sediment of Enhalus acoroides stands were performed at four sites and three times along the year in Cape Bolinao, NW Philippines to test the hypothesis that seagrass growth in tropical environments is limited by the availability of nutrients. Both the nitrogen content (as % DW) and the nitrogen incorporation of E. acoroides leaves increased after the addition of nutrients. The size (g DW per shoot) and the leaf growth rates (g DW per shoot d−1) of E. acoroides shoots also increased after the addition of nutrients. Nitrogen rather than phosphorus was the nutrient limiting shoot size and leaf growth of E. acoroides in the area. The extent of nutrient limitation of E. acoroides showed high variability both in space and time which cannot be directly linked with differences in light or nutrient availability among the experimental sites.
- Physiological and ecological aspects of coral transplantationYap, H. T.; Alvarez, R. M.; Custodio, H. M.; Dizon, R. M. (Elsevier BV, 1998-10)The growth and mortality of transplants of two species of scleractinian corals, Porites cylindrica Dana and P. rus Forskal (1775), were monitored over 16 months in a reef in the northwestern Philippines. Transplants were in two sizes (nubbin, ∼8 cm in length; and fist-sized, ∼8 cm in diameter) and deployed at two depths (1 and 10 m). Specimens at the shallow depth had more rapid growth than the deeper ones. Light had significant effects on coral growth while temperature, salinity, water motion and sedimentation did not. Smaller corals consistently registered greater percentage increases in size as compared to the larger ones. Small transplants of P. cylindrica showed higher percentage growth rates than those of P. rus. Contrary to expectations, there were no differences in transplant mortality due to size. Over the course of the experiment, mortality was generally confined to the shallow depth. It was brought about either by algal competition or by strong water movement.
- Temporal changes in the abundance, leaf growth and photosynthesis of three co-occurring Philippine seagrassesAgawin, N.; Duarte, C. M.; Fortes, M. D.; Uri, J. S.; Vermaat, J. (Elsevier BV, 2001-06)The analysis of the temporal changes in shoot density, areal leaf biomass, leaf growth and parameters of the photosynthesis–irradiance relationship of three tropical seagrass species (Enhalus acoroides, Thalassia hemprichii and Cymodocea rotundata), co-existing in a shallow subtidal meadow in Cape Bolinao, Philippines, shows that species-specific traits are significant sources of temporal variability, and indicates that these seagrass species respond differently to a common environmental forcing. Species-specific differences are much less important as source of variability of the temporal change in chlorophyll concentration of seagrass leaves. The results indicate that the temporal changes in photosynthetic performance of these seagrasses were driven by environmental forcing and their specific responses to it mostly, but the temporal change in their abundance and leaf growth was also controlled by other factors. The significant contribution of species-specific factors in the temporal changes of biomass, growth and photosynthetic performance of co-occurring seagrass species in Cape Bolinao should contribute to the maintenance of the multispecific, highly productive meadows characteristic of pristine coastal ecosystems in Southeast (SE) Asia.
- Influence of light, water motion, and stocking density on the growth and pigment content of Halymenia durvillei (Rhodophyceae) under laboratory conditionsRula, Najeen Arabelle M.; Ganzon-Fortes, Edna T.; Pante, Ma. Josefa R.; Trono, Gavino C. (Springer, 2021-05-17)The tropical red seaweed Halymenia durvillei Bory de Saint Vincent is a potential source of the high-value pigments, r-phycoerythrin (RPE) and r-phycocyanin (RPC). The unique properties of these pigments find many applications—from food to cosmetics, pharmaceuticals, and biomedical research. This study aimed to improve the land-based culture technology of H. durvillei by determining the appropriate combination of light, water motion, and stocking density that would result in high growth performance and high RPE and RPC content. Combinations of two light levels (full light, 100% and reduced light, 67%), two water motion levels (low and moderate), and three stocking densities (50, 100, and 200 g) were studied using 64.5-L glass tanks with flow-through seawater and aeration systems at the outdoor land-based seaweed nursery in Bolinao, Pangasinan, Philippines. After 6 weeks of culture, growth performance (growth rate and productivity) of H. durvillei and phycobiliprotein content were best under a combination of full light (100%), moderate water motion, and 50-g stocking density. The generally low light regime during the experimental period, which coincided with the cold, dry season characterized by shorter days and overcast skies, may have influenced H. durvillei to maximize the use of available resources such as light and possible increased nutrient availability from water motion to promote growth and phycobiliprotein synthesis. Treatments with low stocking densities generally showed satisfactory growth and phycobiliprotein content. This study provides groundwork for future research into mechanisms by which these and other factors affect the growth and physiology of H. durvillei in culture.
- Partial mortality in Porites corals: Variation among Philippine reefsWesseling, Ineke; Uychiaoco, Andre J.; Aliño, Porfirio M.; Vermaat, Jan E. (Wiley, 2001-01)Partial mortality or tissue necrosis was quantified in the massive scleractinian coral Porites at three sites in The Philippines (Bolinao, NW Luzon; Puerto Galera, Mindoro; and El Nido, N Palawan). Overall, 15 ± 1 (mean ± 1 standard error, 642 replicates) percent of colony area was dead, mean colony area was 1135 plusmn; 127 cm2, and lesion density was 1.7 ± 0.1 dm—2. Total live coral cover varied between 20 and 63% in belt transects, and Porites and Acropora cover were inversely correlated. ANOVA models incorporating effects of site, colony size, sedimentation rates, wave exposure and depth were highly significant but explained only a small proportion of the variation observed in lesion density and percent dead area (respectively 8 and 2%). Lesion density was found to vary significantly with site (contributed 29% to this explained variance), decrease with increasing colony area (33%), and increase with increasing sedimentation (23%) and wave exposure (14%). Colony size was significantly explained by the factor site (contributing 61% to the total 29% explained variance) and depth (34%), with the smallest colonies being observed in Bolinao and the largest in El Nido. Densities of lesions were highest in Bolinao, intermediate in Puerto Galera, and lowest in El Nido. This pattern is parallel to intensity of human reef exploitation and opposite to that in colony size, live coral cover and Acropora cover. Since only a small part of the observed variance in partial mortality estimators was explained by the ANOVAs, other factors not quantified here must have been more important (e.g. disease incidence, predation, human exploitation).
- Species composition and plant performance of mixed seagrass beds along a siltation gradient at Cape Bolinao, The PhilippinesBach, S. S.; Borum, J.; Fortes, M. D.; Duarte, C. M. (Inter-Research Science Center, 1998)The response of mixed Southeast Asian seagrass beds to siltation was analyzed based on field data, a transplantation experiment and experimental manipulation of light availability in seagrass populations along a silt gradient at Cape Bolinao,The Philippines. Seagrass species diversity, shoot density and depth penetration declined with increasing amounts of suspended material and increasing water column light attenuation along the silt gradient. The seagrass species could be ranked according to decreasing tolerance to siltation as: Enhalus acoroides > Cymodocea serrulata > Halodule uninervis > Thalassia hemprichii > Halophila ovalis > Cymodocearotundata > Syringodium isoetifolium. A gradual decline in shoot density and depth penetration of the different species along the silt gradient suggested that changes in the vertical light attenuation coefficient in the water column, primarily caused by differences in suspended inorganic solids, was the most important factor affecting seagrass performance. However, inconsistency among the species in response to increasing water depth, artificial shading and transplantation indicated that other factors, such as siltation-derived changes in sediment conditions, contribute to the sequential loss of seagrass species along the silt gradient.
- Comparison of photosynthetic responses of healthy and ‘diseased’ Kappaphycus alvarezii (Doty) Doty using P vs I curveGanzon-Fortes, E. T.; Azanza-Corrales, R.; Aliaza, T. (Walter de Gruyter GmbH, 1993)Healthy and 'diseased' thalli of Kappaphycus alvarezii were collected from two different sites in Bolinao, Pangasinan, northern Philippines. Their photosynthetic responses to varying photon fluence levels we reassessed. The healthy branches had higher photosynthetic rates (expressed in mgO2 gdw"1 h'1) at all light levels and did not show photoinhibition at photon fluence levels of up to 800 μπιοί photons m~2s~!. The 'diseased' branches showed a significant decrease in their photosynthetic performance as manifested by their lower Pmax, increased Ic, and lower alpha, and a photoinhibition above 600 μιηοΐ photons m~2 s"1. Examination of the concentration of pigments — chlorophyll a, r-phycoerythrin and r-phycocyanin, revealed a significant drop in the 'diseased' plants, suggesting the major role played by these pigments in the observed differences in their photosynthetic responses.
- Yield estimates, catch, effort and fishery potential of the reef flat in Cape Bolinao, PhilippinesCampos, W. L.; del Norte-Campos, A. G. C.; McManus, J. W. (Hindawi Limited, 1994-10)Catch, fishing effort and yield estimates of the Cape Bolinao reef flat fishery in Lingayen Gulf, Philippines are provided, based on data collected from May 1987 to April 1988. The dynamics of the dominant species, the rabbitfish Siganus fuscescens, suggest that such fisheries are capable of maintaining a high production in site of heavy fish in pressure. However, yield comparisons with those of other reef fisheries in the Indo-Pacific region, along with characteristics of the catch and the use of multiple gear types, suggest that current extraction rates should not be increased.
- Feeding ecology and trophic role of sea urchins in a tropical seagrass communityKlumpp, David W.; Salita-Espinosa, J. T.; Fortes, M. D. (Elsevier BV, 1993-04)The grazing impact of urchins on seagrass and algal resources, and the relative importance of this to the lower-level trophic flux of a tropical seagrass community were investigated. Thalassia hemprichii (Ehrenb.) Aschers. accounted for 80–93% of seagrass frond biomass at Bolinao in the Philippines. Growth rate of seagrass was 6.6 mm per shoot day−1, or 2.3 mg AFDW per shoot day−1. Production of seagrass fronds per unit area of seagrass bed varied with location from 870 to 1850 mg AFDW m−2 day−1. Urchin density ranged from 0.9 to 4.2 m−2, with Tripneustes gratilla (L.) and Salmacis sphaeroides (L.) being the most common species. Tripneustes gratilla fed mostly on attached seagrass fronds (77–89% of diet), especially Thalassia hemprichii, whereas S. sphaeroides was a generalist, consuming Thalassia hemprichii fronds (13–65%), detached seagrass debris (5–39%), the red alga Amphiroa fragilissima (L.) Lamour. (0–30%), algal-coated sediment and rubble (0–51%) in proportions that varied with the availability of preferred food types. Live Thalassia hemprichii fronds were clearly preferred over macroalgae or dead seagrass fronds by Tripneustes gratilla, but S. sphaeroides consumed all three food types without preference. Both urchins avoided the common brown alga, Sargassum crassifolium J. Agardh. Urchins absorbed 73–76% of organic matter in seagrass fronds with epiphytes (75% of DW), and 55% of that in epiphyte-free fronds. Seagrass debris and the macroalgae A. fragilissima were of lower food quality as they were lower in organic matter, and this matter was absorbed less efficiently by urchins. Rates of ingestion (IR in g WW per urchin day−1) were proportional to body weight (W in g WW) according to the functions: IR = 0.56W0.34 (T. gratilla) and IR = 0.17W0.53 (Salmacis sphaeroides). Predicted grazing impact of urchins on seagrass resources varied spatially and temporally. Estimated annual grazing rate at the main study site was 158 g AFDW m−2, equivalent to 24% of annual seagrass production, but owing to large changes in urchin population structure and density, grazing impact is expected to vary from < 5% to > 100% at different times of year. A synthesis of knowledge on the lower-level trophic pathways in this system indicates that seagrass-urchin and periphyton-epifauna grazing interactions are both important in their contribution to overall trophic flux.
- Topoisomerase II-Mediated DNA cleavage by adocia- and xestoquinones from the Philippine sponge Xestospongia sp.Concepcion, Gisela; Foderaro, Tommaso A.; Eldredge, Glenn S.; Lobkovsky, Emil; Clardy, Jon; Barrows, Louis R.; Ireland, Chris M. (American Chemical Society (ACS), 1995-10)Investigation of an orange Xestospongia sp. sponge collected at Cape Bolinao in northern Luzon, Philippines, yielded the known compounds adociaquinones A and B (1, 2) and six new metabolites, secoadociaquinones A and B (3, 4), 14-methoxyxestoquinone (5), 15-methoxyxestoquinone (6), 15-chloro-14-hydroxyxestoquinone (7), and 14-chloro-15-hydroxyxestoquinone (8). All compounds showed inhibition of topoisomerase II in catalytic DNA unwinding and/or decatenation assays. Furthermore, adociaquinone B showed activity in a KSDS assay, suggesting it inhibits the enzyme by freezing the enzyme-DNA cleavable complex. Interestingly, adociaquinone B did not displace ethidium bromide from DNA or unwind supercoiled DNA, implying it does not intercalate DNA.