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Nitrogen biological fixation and uptake by phytoplankton in subtropical reservoirs with different trophic status

Grant number: 14/02088-5
Support type:Regular Research Grants
Duration: June 01, 2014 - May 31, 2016
Field of knowledge:Engineering - Sanitary Engineering - Water Resources
Principal Investigator:Davi Gasparini Fernandes Cunha
Grantee:Davi Gasparini Fernandes Cunha
Home Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
Assoc. researchers:Igor Renato Bertoni Olivares ; José Albertino Bendassolli ; Maria Do Carmo Calijuri

Abstract

Reservoirs artificial eutrophication affects ecosystem services and may lead to proliferation of Cyanobacteria, some of which are toxic and have a negative influence on the water uses. Nutrient availability, mainly phosphorus and nitrogen, among other factors, regulates phytoplankton development. Biological nitrogen fixation is an important step in the biogeochemical cycle of this nutrient. Some Cyanobacteria are able to convert atmospheric nitrogen (N2) to ammonium, which is then incorporated to amino acids that are essential for cell metabolism. However, biological fixation is energetically expensive, making direct uptake of dissolved nitrogen species preferred by phytoplankton. This research will investigate N2 biological fixation and nitrogen uptake in three reservoirs with different trophic status in the São Paulo State, Brazil. To our knowledge, this will be one of the first studies examining these steps of the nitrogen cycle in subtropical water bodies. The reservoirs will be sampled in the four seasons (summer, autumn, winter and spring) of the years 2014 and 2015 (altogether eight sampling periods). In addition to biotic and abiotic variables of the water, including a qualitative (species and functional groups) and quantitative (density and biovolume) assessment of phytoplankton, nitrogen biological fixation will be measured in situ through an indirect method (acetylene reduction) and a direct one (isotope 15N2). The uptake of nitrate, ammonium and urea will be estimated through laboratory incubations with 15N tracer. Hypotheses regarding the temporal factors and trophic status of the reservoirs will be tested. Statistical analyzes will contribute to the interpretation of the data. The schedule for 24 months will meet the objectives and allow the information dissemination for helping the sustainable management of the subtropical reservoirs. (AU)

Scientific publications (5)
(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)
FERNANDES CUNHA, DAVI GASPARINI; DODDS, WALTER KENNEDY; LOISELLEC, STEVEN ARTHUR. Factors related to water quality and thresholds for microcystin concentrations in subtropical Brazilian reservoirs. INLAND WATERS, v. 8, n. 3, p. 368-380, 2018. Web of Science Citations: 0.
FERNANDES CUNHA, DAVI GASPARINI; DE MELO LIMA, VITORIA FERNANDES; NERI, AMANDA MENEGANTE; MARAFAO, GABRIELA ALBINO; POLI MIWA, ADRIANA CRISTINA; CALIJURI, MARIA DO CARMO; BENDASSOLI, JOSE ALBERTINO; TROMBONI, FLAVIA; MARANGER, ROXANE. Uptake rates of ammonium and nitrate by phytoplankton communities in two eutrophic tropical reservoirs. INTERNATIONAL REVIEW OF HYDROBIOLOGY, v. 102, n. 5-6, p. 125-134, DEC 2017. Web of Science Citations: 4.
DODDS, WALTER K.; TROMBONI, FLAVIA; SALTARELLI, WESLEY APARECIDO; FERNANDES CUNHA, DAVI GASPARINI. The root of the problem: Direct influence of riparian vegetation on estimation of stream ecosystem metabolic rates. LIMNOLOGY AND OCEANOGRAPHY LETTERS, v. 2, n. 1, p. 9-17, FEB 2017. Web of Science Citations: 7.
FERNANDES CUNHA, DAVI GASPARINI; SABOGAL-PAZ, LYDA PATRICIA; DODDS, WALTER KENNEDY. Land use influence on raw surface water quality and treatment costs for drinking supply in Sao Paulo State (Brazil). ECOLOGICAL ENGINEERING, v. 94, p. 516-524, SEP 2016. Web of Science Citations: 17.
FERNANDES CUNHA, DAVI GASPARINI; BENASSI, SIMONE FREDERIGI; DE FALCO, PATRICIA BORTOLETTO; CALIJURI, MARIA DO CARMO. Trophic State Evolution and Nutrient Trapping Capacity in a Transboundary Subtropical Reservoir: A 25-Year Study. Environmental Management, v. 57, n. 3, p. 649-659, MAR 2016. Web of Science Citations: 2.

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