Can free-floating and emerged macrophytes influence the density and diversity of phytoplankton in subtropical reservoirs?

Autor(es)

Fernandes Cunha, Davi Gasparini ^[1] ; Bottino, Flavia ^[1] ; Calijuri, Maria do Carmo ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo EESC USP, Sch Engn, BR-13566590 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: LAKE AND RESERVOIR MANAGEMENT; v. 28, n. 4, p. 255-264, 2012.
• Citações Web of Science: 3

Resumo

Aquatic macrophytes and phytoplankton are important for primary production and metabolism in lentic systems. We investigated the influence of the macrophytes on the phytoplankton in a subtropical reservoir on a seasonal scale (20092010). Our study was one of the first to investigate the effects of free-floating and emerged macrophytes on phytoplankton assemblages in a subtropical reservoir. The concentrations of total phosphorus (2592 mu g/L) and the inflow discharge to the reservoir (6.454.3 m3/s) varied seasonally (p < 0.05, multivariate analysis of variance {[}MANOVA]) and were positively and negatively related with the macrophyte biomass, respectively (principal components analysis {[}PCA]). Light availability was significantly different within the sampling periods (p < 0.05) and influenced phytoplankton densities (0.6 X 103 to 21.0X103 ind/mL) and chlorophyll a (<0.551.3 mu g/L). Abiotic environmental factors and macrophytes influenced the phytoplankton dynamics, and it was difficult to clearly separate these effects. Although the MANOVA did not show seasonal variation of the macrophyte biomass (p > 0.405), the PCA suggested that phytoplankton densities were inversely correlated with the biomass of most of the macrophyte species. Higher phytoplankton diversity and flagellate species were associated with greater plant biomass. Our study has management implications because (1) although not presenting significant seasonal variation, the macrophyte biomass was inversely correlated with phytoplankton densities, and (2) the presence of free-floating and emerged plants induced qualitative shifts in the phytoplankton, increasing the diversity of species. The removal of the macrophytes by management actions (e.g., mechanical removal) or natural forces (e.g., wind effect) might influence the phytoplankton community and the trophic state of subtropical reservoirs. (AU)

• Processo FAPESP: 08/55636-9 - Contribuição ao conhecimento do ciclo do carbono no reservatório de Itupararanga como subsídio para a sustentabilidade da Bacia Hidrográfica do Rio Sorocaba (SP)
• Beneficiário: Maria do Carmo Calijuri
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 09/50842-2 - Heterogeneidade espacial e variabilidade temporal do reservatório de Itupararanga: uma contribuição ao manejo sustentável dos recursos hídricos da Bacia do Rio Sorocaba (SP)
• Beneficiário: Davi Gasparini Fernandes Cunha
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto