Nauka Przyroda Technologie

2007 volume 1 issue 2 #16

Małgorzata Dukowska, Maria Grzybkowska

The response of the benthofauna to river impoundment

Summary. Macroinvertebrates’ responses to environmental changes arising from flow regulations in the large lowland Warta River, central Poland, are presented. Two sites were studied: one below (WAB) and the other, control one, above (WAA) of the man-made Jeziorsko Reservoir. The investigations began in 1988/1989 and were repeated in annual cycles 1991/1992, 1992/1993 and 1995/1996. Upstream, flow was mostly natural and the highest macroinvertebrate abundance was recorded close to the riverbank and decreased sharply toward the mid-river. At WAB the same pattern of benthofauna distribution was only recorded in the first investigated cycle. Later on, the dam’s sluice operations resulted in periodic flow alternations, mostly reductions below natural flow level: the shoreline region (bank habitat) enlarged and contracted in response to dam operations and the bottom was frequently exposed to air. As a result, in this downstream habitat only organisms with high hemoglobin contents, like Chironomidae and Oligochaeta were able to exist. Submersed macrophytes, such as Potamogeton pectinatus and P. lucens appeared during the summer of 1992; they developed in a habitat located several meters from the banks (macrophyte habitat). They were responsible for a substantial increase of macroinvertebrate abundance, especially of epiphytic Chironomidae. Additionally, the retention of FPOM due to a dense bed of macrophytes created favourable conditions for large pelophilous taxa of Chironomidae and Oligochaeta. Downstream of the dam (WAB) at the macrophyte and bank habitats a high concentration of chlorophyll a (periphyton) was also recorded; this finding confirmed that the trophy of this site of the Warta River gradually increased.

Key words: macroinvertebrates, lowland river, dicharge fluctuations, dam reservoir

Full text available in Polish in Adobe Acrobat format:
https://www.npt.up-poznan.net/pub/art_1_16.pdf

Streszczenie w języku polskim:
https://www.npt.up-poznan.net/tom1/zeszyt2/streszczenie-16.html

Corresponding address:
Małgorzata Dukowska
Małgorzata Dukowska
Katedra Ekologii i Zoologii Kręgowców
Uniwersytet Łódzki
ul. S. Banacha 12/16
90-237 Łódź, Poland,
e-mail: mdukow@biol.uni.lodz.pl

Accepted for print: 10.05.2007