Hypoxia in Manila Bay, Philippines during the northeast monsoon     

Jacinto GS  Sotto LP  Senal MI  San Diego-McGlone ML  Escobar MT  Amano A  Miller TW 《Marine pollution bulletin》2011,63(5-12):243-248

Herein we present results from one of the first extensive bay-wide oceanographic surveys of Manila Bay, wherein 31 stations were sampled during the northeast monsoon (cold and dry season). A band of hypoxic bottom water (dissolved oxygen<2.8 mg/L) spanned the midsection of the bay from east to west. Bottom nitrate concentrations (5.7-16.8 μM; avg. 11.1 μM) and total organic carbon values in sediments (1.7-3.1%; avg. 2.4%) were high in the midsection, which coincided with the band of hypoxic bottom water. Physical processes and site-specific accumulation of organic material likely lead to hypoxic conditions in Manila Bay, even during the northeast monsoon period when the water column is relatively well mixed. The results of this study complement the previously reported widespread hypoxia that occurs during the rainy season. Thus, hypoxia may be pervasive in the bay throughout the year, although it varies in intensity and spatial extent.  相似文献   

Nutrient inputs from submarine groundwater discharge on the Santiago reef flat, Bolinao, Northwestern Philippines     

Senal MI  Jacinto GS  San Diego-McGlone ML  Siringan F  Zamora P  Soria L  Cardenas MB  Villanoy C  Cabrera O 《Marine pollution bulletin》2011,63(5-12):195-200

Submarine groundwater discharge (SGD) on the reef flat of Bolinao, Pangasinan (Philippines) was mapped using electrical resistivity, 222Rn, and nutrient concentration measurements. Nitrate levels as high as 126 μM, or 1-2 orders of magnitude higher than ambient concentrations, were measured in some areas of the reef flat. Nutrient fluxes were higher during the wet season (May-October) than the dry season (November-April). Dissolved inorganic nitrogen (DIN=NO3+NO2+NH4) and soluble reactive phosphorus (SRP) fluxes during the wet season were 4.4 and 0.2 mmoles m(-2) d(-1), respectively. With the increase population size and anthropogenic activities in Bolinao, an enhancement of SGD-derived nitrogen levels is likely. This could lead to eutrophic conditions in the otherwise oligotrophic waters surrounding the Santiago reef flat.  相似文献   

Chemical weathering, river geochemistry and atmospheric carbon fluxes from volcanic and ultramafic regions on Luzon Island, the Philippines     

H.H. Schopka  L.A. Derry 《Geochimica et cosmochimica acta》2011,75(4):978-7854

We investigated rates of chemical weathering of volcanic and ophiolitic rocks on Luzon Island, the Philippines. Luzon has a tropical climate and is volcanically and tectonically very active, all factors that should enhance chemical weathering. Seventy-five rivers and streams (10 draining ophiolites, 65 draining volcanic bedrock) and two volcanic hot springs were sampled and analyzed for major elements, alkalinity and ⁸⁷Sr/⁸⁶Sr. Cationic fluxes from the volcanic basins are dominated by Ca²⁺ and Mg²⁺ and dissolved silica concentrations are high (500-1900 μM). Silica concentrations in streams draining ophiolites are lower (400-900 μM), and the cationic charge is mostly Mg²⁺. The areally weighted average CO₂ export flux from our study area is 3.89 ± 0.21 × 10⁶ mol/km²/yr, or 5.99 ± 0.64 × 10⁶ mol/km²/yr from ophiolites and 3.58 ± 0.23 × 10⁶ mol/km²/yr from volcanic areas (uncertainty given as ±1 standard error, s.e.). This is ∼6-10 times higher than the current best estimate of areally averaged global CO₂ export by basalt chemical weathering and ∼2-3 times higher than the current best estimate of CO₂ export by basalt chemical weathering in the tropics. Extrapolating our findings to all tropical arcs, we estimate that around one tenth of all atmospheric carbon exported via silicate weathering to the oceans annually is processed in these environments, which amount to ∼1% of the global exorheic drainage area. Chemical weathering of volcanic terranes in the tropics appears to make a disproportionately large impact on the long-term carbon cycle.  相似文献   

How much are the Bolinao-Anda coral reefs worth?     

Annabelle Cruz-Trinidad  Rollan C. Geronimo  Reniel B. Cabral  Porfirio M. Aliño 《Ocean & Coastal Management》2011,54(9):696-705

The Total Economic Value of the estimated 200 km² of coral reef area straddling the municipalities of Alaminos, Anda, Bani and Bolinao in Pangasinan, Philippines is estimated to reach US$38 million per year consisting mainly of indirect benefits from shoreline protection. Direct use from fisheries, aquaculture, and tourism was valued at US$6 million based on the coral reef interaction index. Non-use values for coral reef conservation were based on estimates of willingness to pay across the three economic sectors plus the general public as a fourth sector. Results varied across sectors and municipalities although the ranges were not wide, especially for fishers. Fishers’ willingness to pay averaged at US$0.25 per individual per year. Except for aquaculture operators in Bolinao, which yielded willingness to pay values reaching US$3 per individual per year, the range of conservation funding was narrow for the three other municipalities for all sectors. Using binary logistic regression (logit model), differences in willingness to pay among fishers are explained by the age, number of children, and employment status.  相似文献   

Development trajectories and impacts on coral reef use in Lingayen Gulf,Philippines     

Annabelle Cruz-Trinidad  Rollan C. Geronimo  Porfirio M. Aliño 《Ocean & Coastal Management》2009,52(3-4):173-180

Management interventions to reduce pressures on coral reefs often include attracting fishers to non-extractive non-fishery supplemental livelihoods. We look at the case of coral reefs in Lingayen Gulf, Philippines to understand the impacts of local (i.e., aquaculture and tourism), regional, and national development on the artisanal fisheries sector. Using household surveys and a coral reef interaction index (CRII), we obtained relative levels of dependency and impacts of fisheries, aquaculture, and tourism on coral reefs for livelihood. Results show that overall dependency on coral reefs remains high despite its decreasing quality. Socio-economic profiles reveal steep hurdles in shifting fishers to aquaculture. Both aquaculture and fisheries will continue to grow and eventually compete for space if left unmanaged further resulting in reduced reef quality. Shifts of fishers to tourism-based and other low-capital requirement mariculture (e.g., sea ranching) are more realistic than the expectation of absorbing fishers into current aquaculture businesses. Strengthening local coastal governance capacity to improve proactive responses for micro–macro development interactive synergy will also help reduce the impacts of development on reefs. Improving safety nets for coastal communities through skills enhancement and supplemental livelihood options that facilitate stewardship and reef recovery is an imperative. Transforming the lessons learned at village level actions to sustain municipal scale programs and institutional cooperation among stakeholders such as through marine protected area networks remain a challenge. Sharing forums and joint financing of coastal resource management remain to be realized through public and private partnerships and expansion of development for investments in social enterprises.  相似文献   

Applicability of the Climate Hazards Group Infrared Precipitation with Stations as Rainfall Input for SWAT Watershed Modeling     

Alejo  Lanie A.  Ella  Victor B.  Saludes  Ronaldo B. 《Water Resources》2021,48(6):925-935

Water Resources - This study assessed the applicability of Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) as rainfall input in watershed modeling using the Soil and Water...  相似文献   

A climate-informed,ecosystem approach to fisheries management     

《Marine Policy》2015

This paper outlines the benefits of using the framework for an ecosystem approach to fisheries management (EAFM) for dealing with the inevitable yet unclear impacts of climate change and ocean acidification on coastal fisheries. With a focus on the Asia-Pacific region, it summarizes the projected biological and socio-economic effects of increased emissions of carbon dioxide (CO₂) for coastal fisheries and illustrates how all the important dimensions of climate change and ocean acidification can be integrated into the steps involved in the EAFM planning process. The activities required to harness the full potential of an EAFM as an adaptation to climate change and ocean acidification are also described, including: provision of the necessary expertise to inform all stakeholders about the risks to fish habitats, fish stocks and catches due to climate change; promotion of trans-disciplinary collaboration; facilitating the participation of all key stakeholders; monitoring the wider fisheries system for climate impacts; and enhancing resources and capacity to implement an EAFM. By channeling some of the resources available to the Asia-Pacific region to adapt to climate change into an EAFM, developing countries will not only build resilience to the ecological and fisheries effects of climate change, they will also help address the habitat degradation and overfishing presently reducing the productivity of coastal fisheries.  相似文献   

Spectral discrimination of giant reed (Arundo donax L.): A seasonal study in riparian areas     

《ISPRS Journal of Photogrammetry and Remote Sensing》2013

The giant reed (Arundo donax L.) is amongst the one hundred worst invasive alien species of the world, and it is responsible for biodiversity loss and failure of ecosystem functions in riparian habitats. In this work, field spectroradiometry was used to assess the spectral separability of the giant reed from the adjacent vegetation and from the common reed, a native similar species.The study was conducted at different phenological periods and also for the giant reed stands regenerated after mechanical cutting (giant reed_RAC). A hierarchical procedure using Kruskal–Wallis test followed by Classification and Regression Trees (CART) was used to select the minimum number of optimal bands that discriminate the giant reed from the adjacent vegetation. A new approach was used to identify sets of wavelengths – wavezones – that maximize the spectral separability beyond the minimum number of optimal bands. Jeffries Matusita and Bhattacharya distance were used to evaluate the spectral separability using the minimum optimal bands and in three simulated satellite images, namely Landsat, IKONOS and SPOT.Giant reed was spectrally separable from the adjacent vegetation, both at the vegetative and the senescent period, exception made to the common reed at the vegetative period. The red edge region was repeatedly selected, although the visible region was also important to separate the giant reed from the herbaceous vegetation and the mid infrared region to the discrimination from the woody vegetation. The highest separability was obtained for the giant reed_RAC stands, due to its highly homogeneous, dense and dark-green stands. Results are discussed by relating the phenological, morphological and structural features of the giant reed stands and the adjacent vegetation with their optical traits. Weaknesses and strengths of the giant reed spectral discrimination are highlighted and implications of imagery selection for mapping purposes are argued based on present results.  相似文献   

A quantitative assessment of vegetable farming on vacant lots in an urban fringe area in Metro Manila: Can it sustain long-term local vegetable demand?     

《Applied geography (Sevenoaks, England)》2013

The aim of this study was to quantitatively assess vegetable production and consumption in an urban fringe area in Metro Manila, the Philippines. We conducted field investigations into vegetable production at a farm within a subdivision, monitored customers for 1 week at the farm's vegetable stand, interviewed customers of the stand, and conducted household monitoring and interviews to identify purchasing behavior. We also conducted an object-based WorldView-2 image analysis of a larger area to identify current and potential future vegetable farming plots and a spatial analysis using GIS to visualize the vegetable production/consumption ratio. We found that about one-third of current vegetable demand could be supplied by greater promotion of vegetable farming in vacant lots and by setting up more vegetable stands at spatial intervals less than 1-km. Subdivision regulations also influenced vegetable farming because of the level of social acceptance of caretakers of vacant lots. The current planning and institutional framework does not consider social contexts in land use and planning. We suggested that a new framework is necessary; it should consider balancing the formation of social capital and formalize planning and institutional procedures to support sustainable local vegetable production.  相似文献   

Statistical Properties of the Immediate Aftershocks of the 15 October 2013 Magnitude 7.1 Earthquake in Bohol,Philippines   总被引：1，自引：1，他引：0  

Rene C. Batac 《Acta Geophysica》2016,64(1):15-25

The aftershock records of the magnitude 7.1 earthquake that hit the island of Bohol in central Philippines on 15 October 2013 is investigated in the light of previous results for the Philippines using historical earthquakes. Statistics of interevent distances and interevent times between successive aftershocks recorded for the whole month of October 2013 show marked differences from those of historical earthquakes from two Philippine catalogues of varying periods and completeness levels. In particular, the distributions closely follow only the regimes of the historical distributions that were previously attributed to the strong spatio-temporal correlations. The results therefore suggest that these correlated regimes which emerged naturally from the analyses are strongly dominated by the clustering of aftershock events.  相似文献