Influence of hydropower dams on the state of macroinvertebrates assemblages in the Virvyte river, Lithuania

Abstract

Macroinvertebrate organization along the Virvyte ˙River was examined to relate biological response in environmental changes. Benthic macroinvertebrates and a range of environmental variables were sampled from three study sections: control, HPP dams and below HPP dams. Total macroinvertebrate taxon number (NT 28), EPT taxon number (NT 13) and Shannon-Wiener diversity index (H´3.85) were the highest in control sites of the river and the smallest in HPP dams (17, 5, 2.75, respectively). Taxon number and total abundance of macroinvertebrates declined significantly both in HPP dams and below them in comparison with the control sites. Total macroinvertebrate abundance in the control sites (698±41 ind.m 2 ) was significantly higher than in HPP dams and below them (430± 21 ind.m 2 and 425±22 ind.m 2 , respectively). The obtained data show that the investigated sections differed in terms of composition and relative abundance of different taxa of macroinvertebrates. Compared to reference conditions (control sites), macroinvertebrate samples from the sites below the dams and in them had relatively more Chironomidae larvae, Oligochaeta and Mollusca and fewer of the more sensitive taxa Plecoptera, Ephemeroptera and Trichoptera. According to Danish Stream Fauna Index and Hilsenhoff biotic index, water quality in the Virvyte Ṙiver control sites was higher in comparison with water quality in HPP dams and below-dam sites.

Basic tools for setting environmental flows at the regional scale: application of the ELOHA framework in a Mediterranean river basin

“…Vaikasas et al . () also found significant higher proportions of Plecoptera taxa in the control sites than in sites below hydropower dams. Reductions of Plecop_a in I A1 , I A2 , I A3 and I A4 do not seem to be related to organic pollution indeed.…”

“…For example, Jones (2013) found ten times more Plecoptera in the natural rivers compared with Magpie River affected by a hydropower dam. Vaikasas et al (2013) also found significant higher proportions of Plecoptera taxa in the control sites than in sites below hydropower dams. Reductions of Plecop_a in I A1 , I A2 , I A3 and I A4 do not seem to be related to organic pollution indeed.…”

“…In particular, frequent high‐magnitude flood pulses of prolonged duration, especially during spring, supported a higher abundance of Coleoptera and Heteroptera specimens and species richness compared with short and low‐magnitude flooding, suggesting that the occurrence of species of Coleoptera and Heteroptera may depend on the duration and intensity of flood pulses. The results of the present study are also consistent with other studies that found significant higher taxonomic diversity in control sites than in sites in and below reservoirs or downstream water diversions (Rader and Belish, ; Céréghino et al ., ; Camargo et al ., ; Vaikasas et al ., ).…”

“…They assume that the increment of habitat generalists in altered ecosystems that some researchers have suggested (Poddubny and Galat, ; Stanford and Ward, ; Aadland et al ., ) is a result of the decline of fluvial specialists with no change in overall abundance. Some works have associated also such increments in the Chironomidae and Oligochaeta taxa with the effects of hydropower dams (Munn and Brusven, ; Jones, ; Vaikasas et al ., ) and it is consistent with I D3 because it is located just below a hydropower dam.…”

Flow Regime Changes: From Impounding a Temperate Lowland River to Small Hydropower Operations

“…The findings from these studies indicate that no comprehensive research on the quantification of environmental issues due to rapid HP flow fluctuations on biotic systems in Lithuanian rivers was carried out. One exception was for macro invertebrate composition [53].…”