How the fluctuations of water levels affect populations of invasive bivalve Corbicula fluminea (Müller, 1774) in a Neotropical reservoir?

Lrp Paschoal,Dp Andrade,G Darrigran

doi:10.1590/1519-6984.09113

Lrp Paschoal, Dp Andrade + Show 1 more

Open Access

https://doi.org/10.1590/1519-6984.09113

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Abstract

Corbicula fluminea is an invasive bivalve responsible for several environmental and financial problems around the globe. Despite the invasive potential of this species, it suffers certain restrictions in lentic environments due to natural phenomena that significantly affect its population structure (e.g. water column fluctuation and sunlight exposure). The present study addresses how temporal decline of the water level in a Neotropical reservoir and exposure to sunlight affect the population structure of C. fluminea. Samplings were carried out twice in the reservoir of Furnas Hydroelectric Power Station (HPS) (Minas Gerais, Brazil), in 2011 and 2012. Population density, spatial distribution and mean shell length of C. fluminea were estimated for each year after sampling in 51 quadrats (0.0625m2) placed on three transects at different distances along the reservoir margins (0, 10 and 20 m from a fixed-point). We observed a predominance of C. fluminea in both years, with a simultaneous gradual decrease in density and richness of native species in the sampling area. Significant differences in density of C. fluminea were registered at different distances from the margin, and are related to the temporal variability of physical conditions of the sediment and water in these environments. We also registered a trend toward an increase in the density and aggregation of C. fluminea as we moved away from the margin, due to the greater stability of these areas (>10 m). The mean shell length of C. fluminea showed significant difference between the distinct distances from the margin and during the years, as well as the interaction of these factors (Distances vs.Years). These results were associated with the reproductive and invasive capacity of this species. This study reveals that these temporal events (especially water column fluctuation) may cause alterations in density, spatial distribution and mean shell length of C. fluminea and the composition of the native malacofauna in Neotropical lentic environments.

Highlights

Reservoirs are artificial man-made environments and are considered intermediary water bodies because they depend on water detention time and variation between storage and discharge of water (Tundisi et al, 2008)
Four mollusc species were recorded, with a predominance of Corbicula fluminea in both years (N: 1,122 [2011] and 1,118 [2012])
It is extremely important to evaluate the effects of density and biomass changes in bivalve populations in these ecosystems when they are exposed to different environmental effects, such as desiccation, flooding, drought, etc

Summary

Introduction

Reservoirs are artificial man-made environments and are considered intermediary water bodies because they depend on water detention time and variation between storage and discharge of water (Tundisi et al, 2008). Mollusc populations present high densities and significant biomass (Mansur et al, 2003; Santos et al, 2012). They are frequently used as biomonitors, because in addition to being sensitive to pollution and eutrophication, they are capable of accumulating several pollutants found in aquatic environments (Darrigran, 1999; Furley and Oliveira Filho, 2000). Molluscs play an important role in organic matter cycling in aquatic ecosystems (Darrigran and Lagreca, 2005; Vaughn, 2010)

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