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C. P. C. David Y. Y. Sta. Maria F. P. Siringan J. M. Reotita P. B. Zamora C. L. Villanoy E. Z. Sombrito R. V. Azanza 《Environmental Geology》2009,58(2):447-454
The supply of nitrogen and phosphorus in coastal zones through time is reflected in the nutrients’ concentration in the sediment
record. Five aquaculture sites in the Philippines were investigated in an effort to establish how long-term changes in land
and coastal water use could have led to biogeochemical modifications affecting the coastal ecosystem. Samples from study sites
show a narrow concentration range for nitrogen and did not reveal any significant trend through time. In contrast, phosphorus
concentrations in most sites start at less than 20 ppm in sediments 30 years and older. The phosphorus value continuously
increase in younger sediments, with each site having a different magnitude change as well as timing of when the major increase
happened. The uppermost 10 cm, representing the last 15 years in sites with age control, typically show a 2- to 3-fold increase
in P load values. Historical increase in nutrient load also coincides with harmful algal bloom events in each area; when effective
P input exceeded 130 kg/km2 per year. Lastly, the observed increase may be attributed to several factors including physical attributes of the area, urbanization
of coastal zones, but most importantly in the proliferation of aquaculture activities. 相似文献
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Mangrove forests can provide important cross-boundary subsidies of organic matter to adjacent habitats through the production, export, decomposition and assimilation of litter. We quantified two of these components in a temperate mangrove forest in Whangamata Harbour, New Zealand: 1) litter production; and 2) decomposition rates as a function of tidal elevation, sediment type and burial depth. Litter traps sampled monthly for a year measured an annual detrital input of 3.24–5.38 t DW ha?1, of which 77% occurred in summer. Decomposition rates depended on litter type, with leaves decomposing faster (63 d to decay by 50%) than pneumatophore and wood material (316 and 460 d, respectively). Buried leaf and wood litter decomposed 1.3–1.4 times slower than litter on the sediment surface; however, tidal elevation and sediment type (mud vs. sand) had no effect. The slow decay of litter (an order of magnitude slower than tropical mangrove litter) suggests that its incorporation into temperate marine food webs may be relatively slow. 相似文献
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Glibert PM Azanza R Burford M Furuya K Abal E Al-Azri A Al-Yamani F Andersen P Anderson DM Beardall J Berg GM Brand L Bronk D Brookes J Burkholder JM Cembella A Cochlan WP Collier JL Collos Y Diaz R Doblin M Drennen T Dyhrman S Fukuyo Y Furnas M Galloway J Granéli E Ha DV Hallegraeff G Harrison J Harrison PJ Heil CA Heimann K Howarth R Jauzein C Kana AA Kana TM Kim H Kudela R Legrand C Mallin M Mulholland M Murray S O'Neil J Pitcher G Qi Y Rabalais N Raine R Seitzinger S Salomon PS Solomon C 《Marine pollution bulletin》2008,56(6):1049-1056
The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed. 相似文献
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A multivariate biochronological analysis of the Plio‐Pleistocene Iberian rodent fossil record is presented. Among more than 300 fossil sites, 49 sites have been selected. The ordination of the fossil sites selected from the Iberian Peninsula has been achieved by the appearance event ordination method. After calibration of this ordination with geochronological dates at some of the localities, numerical dates are proposed for all the localities studied. Hence, mammal fossil sites non‐datable by other means (palaeomagnetism, radiometric dating, etc.) have been dated with a relatively high degree of confidence. Final results allow dating of boundaries between the Plio‐Pleistocene European Land Mammal Ages (ELMAS) or the Mammal Neogene (MN) units. These boundaries agree with previous studies using magnetostratigraphical calibration of these scales. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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San Diego-McGlone ML Azanza RV Villanoy CL Jacinto GS 《Marine pollution bulletin》2008,57(6-12):295-301
The coastal waters of Bolinao, Pangasinan, Philippines experienced environmental changes over a 10-year period (1995-2005), the most significant effect of which was the major fish kill event in 2002 that coincided with the first reported Philippine bloom of a dinoflagellate Prorocentrum minimum. Days before the bloom, dissolved oxygen was < 2.0 mg/l in the waters that were stratified. These conditions may be linked to the uncontrolled proliferation of fish pens and cages to more than double the allowable limit of 544 units for Bolinao waters. Mariculture activities release organic matter from unconsumed feed and fecal material that accumulate in the water and sediments. In over 10 years, water quality conditions have become eutrophic with ammonia increasing by 56%, nitrite by 35%, nitrate by 90%, and phosphate by 67%. The addition of more fish pens and cages placed additional stress to this poorly flushed, shallow area that affected water quality due to changes in the water residence time. 相似文献
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The community composition and production of phytoplankton in fish pens of Cape Bolinao, Pangasinan: a field study 总被引:1,自引:0,他引:1
From 1995 up to the present, fish pens proliferated in the municipal waters of Bolinao, northern Philippines. Since then, fish kills and phytoplankton blooms have been recurrent. Have fishpens altered the phytoplankton community composition and production of these waters? The phytoplankton community in Cape Bolinao, Lingayen Gulf is typical of a tropical coastal area where diatoms alternate with dinoflagellates during the dry and wet seasons. In the nutrient-rich fish pens, phytoplankton in this study showed a lower diatom/dinoflagellate ratio and unusually high phytoplankton counts of 10(4) cells/l and even as high as 10(5) cells/l. Correlations between physico-chemical parameters, phytoplankton production and community composition were made in 2001. This paper tried to explain the occurrence of a Cylindrotheca closterium bloom (10(5) cells/l), during the dry season of the same year and a Prorocentrum minimum bloom (4.7 x 10(5) cells/l), which accompanied a massive fish kill during January 2002. 相似文献
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