Effects of low nitrogen-phosphorus ratios in the phytoplankton community in Laguna de Bay, a shallow eutrophic lake in the Philippines
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The effects of low nitrogen-phosphorus ratios on microalgae from a large eutrophic freshwater lake in the Philippines were investigated. Natural microalgal populations from Laguna de Bay, the largest lake in the Philippines, were cultured using three different nitrogen-phosphorus weight ratios (2N:1P; 6N:1P and 12N:1P) at two phosphorus concentrations (0.25 and 0.5 mg l–1) in each case. The growth and genera composition of the cultures under the different treatments were followed for a 12-week period. Community level responses were assessed based on species richness (s), Shannon-Wiener Index (H’), Simpson Index (λ) and Evenness (J’). Among the different microalgal groups, only the chlorophytes showed a significantly higher density in response to the 12N:1P treatment at the higher P concentration, indicating that the nutrient ratio had a significant interaction with the nutrient levels used in the experiments. The genera found in the different treatments were generally similar; however, the degree of dominance of some varied with treatment during the experiment. The succession of dominant genera also differed among the N:P treatments. The diatoms like Fragilaria, Aulacoseira (= Melosira) and Nitzschia dominated the lowest N:P. On the other hand, chlorophytes (Kirchneriella and Scenedesmus) dominated the highest N:P treatment, particularly from the second to the seventh week of the experiments with the diatoms becoming co-dominant only towards the eighth week until the end of the experimental. The 6N:1P treatment showed a mixed dominance between the diatoms and the chlorophyte genera. The various indices of diversity indicate significantly lower diversity only in the 12N:1P at 0.5 mg l–1 P and not in 12N:1P at 0.25 mg l–1 P.
CitationCuvin-Aralar, M. L., Focken, U., Becker, K., & Aralar, E. V. (2004). Effects of low nitrogen-phosphorus ratios in the phytoplankton community in Laguna de Bay, a shallow eutrophic lake in the Philippines.
Chlorophylls; Community composition; Eutrophic lakes; Freshwater lakes; Genetic diversity; Growth; Nitrogen; Nutrients (mineral); Phosphorus; Phytoplankton; Species diversity; Hydrobiology; Phytoplankton; Aulacoseira; Fragilaria; Kirchneriella; Melosira; Nitzschia; Scenedesmus; Philippines, Luzon I., Laguna de Bay; Nutrient ratios
This study was part the doctoral dissertation of the senior author at Hohenheim University, Germany. Funds for the study was provided in part by the European Union STDIII Program as component of the project ‘Laguna de Bay, Philippines: An Ecosystem Approach for Sustainable Management’ under contract CT 94-0334. Additional funds were provided by SEAFDEC/AQD under project code FS-03-F97B. The Deutschen Akademischen Austauschdienstes DAAD supported the senior author’s stay in Germany. Mr F. Reyes assisted in the culture and field collection of the samples. Dr. SF Baldia assisted in the identification of the samples.
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Conference paperRA Francisco, MR Pundavela, JM Granali, LA Tumabiene, JP Alpino & VV Elmido - In Conservation and Ecological Management of Philippine Lakes in Relation to Fisheries and Aquaculture: Proceedings … Seminar-Workshop held on October 21-23, 1997, INNOTECH, Commonwealth Ave., Diliman, Quezon City, Philippines, 2001 - Aquaculture Department, Southeast Asian Fisheries Development Center; Philippine Council for Aquatic and Marine Research and Development (PCAMRD), Department of Science and Technology; Bureau of Fisheries and Aquatic ResourcesLake Mahagnao in Burauen, Leyte (10° 52.15' N and 124° 51.32' E) lies 26 m above sea level. It is surrounded by a mountain range that includes a dormant twin volcano. A bathymetric survey established 122 sampling stations using Global Positioning System. The stations formed transect lines across the lake. A bathymetric map of Lake Mahagnao was generated with the use of the SURFER software. Lake Mahagnao has a shoreline of 15,590 m and surface area of 15.75 ha. The deepest portion of the lake is 18.75 m. The mean pH of the water is 6.58; water surface temperature, 27oC; and water visibility, 1.64 m. Eighty-one species were identified as primary producers. Station 5, the deepest portion of the lake, had the highest phytoplankton density at 4,716 cells/ml and Station 2 had only 634 cells/ml. Cyanobacteria were the most abundant in all the sampling stations.
Conference paperJC Francisco & TR Perez - In Conservation and Ecological Management of Philippine Lakes in Relation to Fisheries and Aquaculture: Proceedings … Seminar-Workshop held on October 21-23, 1997, INNOTECH, Commonwealth Ave., Diliman, Quezon City, Philippines, 2001 - Aquaculture Department, Southeast Asian Fisheries Development Center; Philippine Council for Aquatic and Marine Research and Development (PCAMRD), Department of Science and Technology; Bureau of Fisheries and Aquatic ResourcesPhytoplankton composition and density were studied in three (3) stations in West Bay, Laguna Lake. Blue-green algae and diatoms were the most abundant in terms of cell density. Green algae had the most number of species. Diatoms predominated in the early parts of the year, under intense light conditions. Pulses of green algae were evident toward the end of the year, under high nitrogen concentrations. BIP (Biological Index of Pollution) values were very much affected by seasonal variations in the phytoplankton community.
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Fisheries Research Journal of the Philippines, 1981 - Fisheries Research Society of the PhilippinesQuantitative determination of the algal population, in terms of cells/ml and biomass/ml, was conducted during the first month of growing P. monodon postlarvae in Laguna Lake. Algae were sampled from each side of net cages at depths of 15, 30 and 45 cm below the water surface. Accumulation of algae appeared to be influenced by the direction of water flow. Moreover, growth of algal species was inversely proportional to depth of water. After two weeks, algal biomass was estimated to reach 4.5 kg per cage (1 x 1 x 1 m). Diatoms (Chrysophyta) predominated throughout the experimental period followed by members of Cyanophyta and Chlorophyta.