Fish diversity and community structure in two small tributaries of the Paran� River, Paran� State, Brazil

Abstract

In eleven sites on two small tributaries of the Parand River (North-West Parand State)| 6 .8 and 4 .0 km in length| 1263 fish specimens of 28 taxons and 14 families were collected using electrofishing . Up to twelve years ago the catchments of the two rivers were covered by tropical jungle ; this has now been replaced by pasture and arable fields . Mean diversity indices of Simpson and Shannon indices were close to 0 .6| which would indicate that human impact affected fish populations although the river beds have retained their original shape| except cleared of riparian trees . Despite their close location (about 18 km)| the two streams differed from each other in their fish faunal composition . The distinctive nature of the fish communities in the two streams was a result of: conductivity| pH| also hiding places| riparian vegetation| submerged macrophytes and depth and width of the rivers .

Temporal and spatial distribution of the ichthyofauna in two streams of the upper Rio Paraná basin

“…Thus the results allowed us to infer that the Caracu had higher availability of microhabitats for small fishes at its mouth than the São Pedro. Penczak et al (1994), working in the Caracu and another stream of the same region, used other fishing gears (basically electrofishing), and different data analysis. Their results are not comparable because of the selectivity of the fishing gear employed.…”

Influência da urbanização sobre as assembléias de peixes em três córregos de Maringá, Paraná

“…Mesmo a família Characidae não sendo exclusiva de riachos, seus membros geralmente formam o principal conjunto de espécies de meia água nestes ambientes (BUCKUP 1999). PENCZAK et al (1994), PAVANELLI & CARAMASCHI (1997) e CAS- TRO & CASATTI (1997) verificaram em seus estudos em riachos na bacia do alto Rio Paraná, a presença de espécies constituintes desta família (Astyanax spp.) entre as mais abundantes nos locais estudados.…”

Variation of the ichthyofauna along the Goioerê River: an important tributary of the Piquiri-Paraná basin

“…The causes of the low richness and abundance are varied, but they are commonly reported in the literature. Near headwaters, most organisms rely on allocthonous food sources (VAnnote et al, 1980;PenczAck et al, 1994;MAtthews, 1998;Abes & Agostinho, 2001). However, in the specific case of Gurucaia, the site is located in a mosaic of rotational mechanized plantations of soybeans, wheat and corn, whose management brings impacts caused by the carrying of soil particles and agricultural inputs connected to these sediments by the rains.…”