Ricardo Barbieri

The chemical composition of some aquatic macrophyte species and implications for the metabolism of a tropical lacustrine ecosystem — Lobo Reservoir, São Paulo, Brazil

The concentration of nutrients in Nymphoides indica (L.) O. Kuntze, Pontederia cordata L., Andropogon bicornis L. and Utricularia breviscapa Griseb was analyzed at monthly intervals from January 1980 through February 1981. The macrophytes strongly influenced the organic nitrogen and phosphorus concentration of the water, mainly in those months of intense plant decomposition after a dry period. The monthly changes in chemical composition of the macrophytes and in water are discussed.

Limnological characteristics of three aquatic systems of the pre-amazonian floodplain, Baixada Maranhense (Maranhão, Brazil)

Preliminary information is provided on physical and chemical characteristics of three aquatic systems in the pre-amazonian floodplain, Baixada Maranhense: Pindare (Viana Lake) and the Pericuma and Turiacu rivers. Emphasis is given to the nutrients analyzed spectrophotometrically from the bottom sediments of Viana Lake. The water bodies differ from each other with respect to conductivity, total suspended solids and nutrient contents in the water, with higher values (except for total nitrogen) in the dry season. The main factors responsible for such differences, besides the annual flood, are the presence of macrophytes on Pericuma, riparian vegetation on Turiacu (both systems with lotic characteristics) and water buffalo at Viana Lake. Bottom sediments with low nutrient concentrations at Viana Lake may be due to the rapid mineralization of organic matter in this lentic environment.

Grain size distribution of particulate matter and sediment in extensive freshwater bodies in pre-Amazonian floodplain, Baixada Maranhense, Brazil

The limnology of the Amazon River and its floodplain ecosystems has been vigorously studied (FISHER & PARSLEY 1979, SIOLI 1984, FoRSBERG et al. 1988, MELACK & FISHER 1990, RICHEY et al. 1990, DEVOL et al. 1995, JUNK & WEBER 1996, IBANEZ 1997, JUNK 1997, BOZELLI & GARRIDO 2000, CARNEIRO et al. 2002, FARJALLA et al. 2002, ROLAND et al. 2002, GUENTHER & BOZULL 2004). The freshwater bodies in floodp1ains provide high productivity and biodiversity, which are sustained with various biogeochemica1 cycling. We a1so have some data from rivers and 1akes in the pre-Amazonian floodplain (REm & TuRNER 1988, BARBIERI et al. 1989, IBANEZ et al. 2000). The limnological knowledge of this aquatic system, especially the grain-size configuration of particulate matter and bottom sediment, however, has been limited. The aim of this study was to clarify the characteristics of fine size distribution o f particulate matters and bottom sediments in the Turiacu, Pericuma, and Pindare aquatic systems, in a typica1 pre-Amazonian floodplain ecosystem, Baixada Maranhense, Maranhao, Brazíl, which 1ies in the southem part of the Amazon River estuary.