Advanced search
Start date
Betweenand

Biodiversity and distribution of planktonic diatoms and present in the surface sediments in an deep and oligotrophic reservoir (Cantareira syatem, Jaguari-Jacareí reservoir)

Grant number: 09/11731-0
Support type:Scholarships in Brazil - Master
Effective date (Start): March 01, 2010
Effective date (End): February 29, 2012
Field of knowledge:Biological Sciences - Ecology
Principal Investigator:Denise de Campos Bicudo
Grantee:Majoi de Novaes Nascimento
Home Institution: Instituto de Botânica. Secretaria do Meio Ambiente (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

This study aimed to evaluate the biodiversity and temporal and spatial distribution of planktonic diatoms as well as of diatom present in the surface sediments of the Reservoir Jaguari-Jacareí (Cantareira System), to contribuite with characterization of the ecological quality of the largest source supplier of the MRSP. Also aimed to increase the ecological knowledge of diatoms from tropical reservoirs. Samples were taken in nine locations close to the monitoring SABESP locations. The water sampling was performed over vertical profile during winter and summer seasons, and the sediment surface in winter. The analysis included physical, chemical and diatom of water and sediment. A total of 62 specific infraspecific plankton taxa and 65 sediment taxa were found. The structural organization of planktonic diatoms was influenced by the seasonal, followed by spatial scale. During the winter, the water circulation favored Aulacoseira species (A. granulata, A. granulata var. angustissima and A. ambigua). In the summer period, small planktonic species centric (Thalassiosira rudis, Discostella pseudostelligera and Cyclotella meneghinana) were favored by the regime of stratification and the high water temperatures. There was influence of rivers on community organization due to physical factors (turbulence and turbidity), favoring centric species (A. granulata var. granulata, A. granulata var. angustissima, A. ambigua and T. rudis). The distribution of species in the sediment was particularly sensitive to the rivers and the depth of the reservoir. At the riverine stations benthic diatoms dominated (Diadesmis contenta, Encyonema silesiacum, Gomphonema parvulum, Navicula cryptocephala and Luticola acidoclinata), and in the deeper stations, the mos abundant were planktonic species (Aulacoseira tenella, A. ambigua, A. granulata var. granulata, A. granulata var. angustissima, Cyclotella meneghiniana, Discostella pseudostelligera and Thalassiosira rudis). It confirmed the integrative function of sediments, demonstrating the dominance of pelagic habitat in the reservoir and benthic representatives only in the most shallow and close to the rivers. The comparison between planktonic communities and those present in the sediments revealed that the sediment incorporate information from both periods. This study expands the ecological knowledge of two known species: Achnanthidium catenatum and Aulacoseira tenella, respectively indicator of environmental changes not associated with eutrophication and non-degraded environments. The Reservoir Jaguari-Jacareí was classified as ultra-oligotrophic to oligotrophic, except on sites that are influenced by rivers Jaguari and Jacarei, classified as mesotrophic, and seems to show an eutrophication process. We emphasize the need for urgent action to control the supply of nutrients from the cities that are part of river basins Jaguari and Jacareí (mostly the latter) that can put at risk the largest source of RMSP.