Drift of Limnoperna fortunei bivalve in the Middle Paraná River (Argentine)

MONTALTO LUCIANA; ROJAS MOLINA FLORENCIA; VASCHETTO PABLO

Buenos Aires

Conferencia; Marine & Freshwater Invasive Species: Ecology, Impacts, and Management.; 2016

MACN-CONICET y Aquatic Ecosystem Health and Management Society

This research evaluated the Limnoperna fortunei drift in the Middle Paraná River floodplain in relation to caudal and vertical, lateral and daily rhythm distribution in the water column. Limnoperna fortunei drift samples were collected during spring-autumn 2012-2013, at four lotic habitats with different caudal (main channel and different secondary channels); in four sites in a transect perpendicular to the banks in the Colastiné secondary channel); and during 24 h at 3-h intervals in Paraná River main channel. In each site/hour, samples were simultaneously collected in the surface and at the bottom during 10 minutes, using conical nets (1-m long, 250-µm mesh size). Three replicates of each sample were taken. Several physical and chemical parameters were measured. Drift rate was higher in the center than in the banks of Colastiné River. Daily distribution shows the highest drift rate during the 3 am ? 9 am period, but from then drift rate decreased gradually until 18 pm when an increase occurs. In relation to the caudal of rivers, the drift rate decreased from the main channel to the secondary channels. In all sites the drift rates were similar between surface and bottom and the individuals were similar in size in both depths. More than 80% of individuals collected in the environments were < 1 mm in length. In addition, the individuals of nocturnal periods were larger than those of diurnal period. The present study provides new information about L. fortunei drift in the Paraná River floodplain. Results showed that the specimens of L. fortunei founded in drift are principally represented by prereproductive individuals and the drift rates founded were principally related to river caudal, suggesting that the Paraná River main channel and the large secondary channels are important corridors for the dispersal and recruitment of L. fortunei population.