Diversity patterns and freshwater molluscs similarities in small water reservoirs

Tomáš Čejka

doi:10.5817/mab2011-10-5

Abstract

The survey presents the molluscan fauna from six impoundment systems of two sides (NW and SE) of the Small Carpathians. Altogether 25 species (15 gastropod and 10 bivalve) species were identified in reservoirs and their subsystems (inflows and outlets). The number of species per site ranged from 2 to 12, the mean number of species per site was 7. The mean number of individuals per site ranged from 15 to 905 (mean 174) ind/m². Radix auricularia, R. ovata, Gyraulus albus, Gyraulus parvus/laevis, Hippeutis complanatus and Pisidium casertanum were present in more than 50% of reservoirs. The most abundant and frequent species in the entire area and all subsystems were Pisidium casertanum, Pisidium subtruncatum and Gyraulus parvus/laevis. Faunistic similarity indices indicate moderate degree of beta diversity i.e., differentiation among the sites; good separation of sites by cluster analysis indicates a different composition among inflows/outlets and littoral molluscan faunas of reservoirs.

Highlights

Impoundments are features that significantly slow the rates of transport of water; elevate water loss to evaporation; alter rates, pathways and locations of chemical reactions in freshwater and disrupt freshwater aquatic habitats by fragmenting water flow to the lower part of the watershed (Smith et al 2002)
The study was located around the Small Carpathian Mts., SW Slovakia (48°24' N, 17°15' E)
Two types of sampling devices were used to collect benthic macroinvertebrates: for quantitative sampling in dex (Iw = total no. of species divided by the mean number of species; Whittaker 1972), and its variant (Imax = total no. of species divided by the number of species in the richest site recorded), as indicators of faunal differentiation between sites in the same region (Cameron & Pokryszko, 2005)

Summary

Introduction

Impoundments are features that significantly slow the rates of transport of water; elevate water loss to evaporation; alter rates, pathways and locations of chemical reactions in freshwater and disrupt freshwater aquatic habitats by fragmenting water flow to the lower part of the watershed (Smith et al 2002). The damming system consists of three main subsystems – inflow, reservoir and outlet. Molluscan surveys absent from the small water reservoir systems in the area around and in the Small Carpathians. The study was located around the Small Carpathian Mts., SW Slovakia (48°24' N, 17°15' E). Six impoundment subsystems (inflows, littoral of the reservoirs and their outlets, see Figs 1–6) belong to two watershed were chosen (Váh and Morava Rivers, see below). The reservoirs are used for water supply and fish stocking; reservoirs belonging to the Morava River watershed were Kuchyňa, Lozorno, and Vývrat are situated on the west side of the Small Carpathiabns up to 260 m a.s.l. The inflows flow through the protected landscape area “Small Carpathians”; the reservoirs Kuchyňa and Lozorno are part of the Ramsar Convention on wetlands (Klementová & Juráková 2003). The outlets of all six reservoirs are altered by channel regulation and high water fluctuation depending on discharge manipulation, together with organic pollution from agriculture and urban waste

Mollusca sampling

Sphaerium corneum sensu lato

Similarity of communities

Speciess richness

Characteristic species