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The production and fate of algal extracellular polysaccharides in an eutrophic reservoir of the Tietê River, SP, Brazil

Abstract

The Barra Bonita reservoir is formed by the junction of the Piracicaba and Tietê rivers with a total area of 384 Km2 . It is the first of a series of six big reservoirs located at the medium Tietê basin, which has an area of approximately 33,000 Km2 and a population of 5,000,000 inhabitants. It is located 250 km far from the city of São Paulo, capital of the São Paulo State with 15,000,000 inhabitants and receives part of its industrial and domestic sewerage. The reservoir was constructed with the function of generating electric energy. In the present days it is also used as urban water furnishing, fishing, recreational means, and fluvial transport and for agricultural irrigation. In the last 1 5 years, phytoplankton primary productivity has triplicate (Calijuri, 1999), showing an eutrophication process going on as a result of the increase in nutrient concentration. Blooms of Cyanobacteria such as Anabaena spp and Microcystis spp (potentially toxic), besides the diatom Aulacoseira spp are common and periodical lyconstant, however recently have been more intense. This fact affects the local waters use and imposes health risks to the population. Besides this, the high particulate material sedimentation will reduce de reservoir life. Most of the dominant species of the reservoir (Anabaena spp, Microcystis spp, Kirchnerielia obesa, Staurastrum spp and others) are high mucilage producers and the responsible for the production of approximately 12,000 metric ton/year of C-CHO in extracellular polysaccharides (figure obtained from primary productivity data). These are carbon rich compounds and represent a reasonable part of the organic matter produced byphotosynthesis, which is released by algal cells and are accessible to heterotrophic microorganisms even without the microalgal cell death and its decomposition. Moreover, this released dissolved polysaccharide present several environmental fate, such as metal complexation, production of TEP (transparent exopolymer particle), humic substance formation, carbon transport to the sediment and transfer of toxic metals to food web and sediments. It may also promote specific association's algal bacteria. The aims of this project are to investigate the ecological functions of the extracellular polysaccharides of microalgal origin (EPS), which represent a considerable part of the organic matter produced in the reservoir. Details are to be obtained in relation to several routes of the carbon cycle, such as humic substance formation and TEP use by filter feeders, not routinely investigated. The results obtained in the present project may be used for eutrophication management and water restoration programs. Besides these, the project also aims to serve as personal training for non conventional limnologic techniques… (AU)

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Scientific publications (13)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
GIROLDO‚ D.; VIEIRA‚ A.A.H.; PAULSEN‚ B.S.. Microbial degradation of extracellular polysaccharides released by a tropical strain of Staurastrum orbiculare (Zygnematophyceae). PHYCOLOGIA, v. 44, n. 6, p. 671-677, . (99/07766-0)
VIEIRA‚ AH; GIROLDO‚ D.; ORTOLANO‚ PI. Aggregate formation in axenic and microbial co-inoculated batch cultures of Aulacoseira granulata (Bacillariophyceae). Acta Limnologica Brasiliensia, v. 18, n. 1, p. 1-7, . (99/07766-0)
BITTAR‚ TB; COLOMBO‚ V.; VIEIRA‚ AAH. Release of Organic Carbon by Cells of Microcystis aeruginosa (Cyanobacteria) in Culture under Different Irradiances.. Acta Limnologica Brasiliensia, v. 17, n. 1, p. 15-26, . (99/07766-0)
GOUVÊA, S. P.; VIEIRA, A. A. H.; LOMBARDI, A. T.. Copper and cadmium complexation by high molecular weight materials of dominant microalgae and of water from a eutrophic reservoir. Chemosphere, v. 60, n. 9, p. 1332-1339, . (99/07766-0)
GIROLDO, DANILO; VIEIRA, ARMANDO A. H.; PAULSEN, BERIT S.. Extracellular polysaccharides produced by a tropical cryptophyte as a carbon source for natural bacterial populations. European Journal of Phycology, v. 40, n. 3, p. 241-249, . (99/07766-0)
GIROLDO, DANILO; ORTOLANO, PEDRO I. C.; VIEIRA, ARMANDO A. H.. Bacteria-algae association in batch cultures of phytoplankton from a tropical reservoir: the significance of algal carbohydrates. Freshwater Biology, v. 52, n. 7, p. 1281-1289, . (99/07766-0)
CRISTINA SOUZA FREIRE NORDI; THAYS GABRIELLE WENZEL FERREIRA CAVAGLIERE; ARMANDO AUGUSTO HENRIQUES VIEIRA; OTACIRO RANGEL NASCIMENTO. Efeito caotrópico do íon lítio na permeabilidade da cápsula polissacarídica da microalga Ankistrodesmus gracilis (Reinsch) Korsikov (Chlorophyceae). Acta Botanica Brasilica, v. 20, n. 2, p. 449-454, . (99/07766-0)
PANHOTA, RAFAEL SPADACCIA; SANTINO, MARCELA BIANCHESSI DA CUNHA; BIANCHINI, IRINEU. Oxygen consumption and formation of recalcitrant organic carbon from the decomposition of free-floating macrophyte leachates. Environmental Science and Pollution Research, v. N/A, p. 13-pg., . (99/07766-0)
GOUVÊA‚ S.P.; VIEIRA‚ A.A.H.; LOMBARDI‚ A.T.. No effect of N or P deficiency on capsule regeneration in Staurodesmus convergens (Zygnematophyceae‚ Chlorophyta). PHYCOLOGIA, v. 41, n. 6, p. 585-589, . (99/07766-0)
ARRUDA FATIBELLO‚ S.H.S.; HENRIQUES VIEIRA‚ A.A.; FATIBELLO-FILHO‚ O.. A rapid spectrophotometric method for the determination of transparent exopolymer particles (TEP) in freshwater. Talanta, v. 62, n. 1, p. 81-85, . (99/07766-0)
CHOUERI, RODRIGO B.; MELÃO, MARIA DA GRAÇA G.; LOMBARDI, ANA T.; VIEIRA, ARMANDO A. H.. Effects of cyanobacterium exopolysaccharides on life-history of Ceriodaphnia cornuta SARS. Journal of Plankton Research, v. 29, n. 4, p. 339–345, . (99/07766-0)
LOMBARDI‚ AT; HIDALGO‚ TMR; VIEIRA‚ AAH. Copper complexing properties of dissolved organic materials exuded by the freshwater microalgae Scenedesmus acuminatus(Chlorophyceae). Chemosphere, v. 60, n. 4, p. 453-459, . (99/07766-0)

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