engleski

Post-disturbance changes of macroinvertebrate assemblages downstream of a large dam in the Dinaric karst river Dobra (Croatia)

Dinaric Mountains’ rivers represent one of the most important hotspots of the European freshwater biodiversity. However, large dams continue to be built and many more are planned on these rivers, despite the scarce knowledge about the dam impact on aquatic biodiversity in this area. In 2010 a new large dam (52.5 m high) on the karst river Dobra (Croatia) was finished and closed. Temporal changes of macroinvertebrate assemblages were examined at the site located 460 m downstream of the dam in the period before (2007- 2008) and after the dam closure (2010-2015). Replicate samples of macroinvertebrates were collected in mosses and on stony substrate using hand net. The new dam caused drastic short term changes in water quality, and permanent changes of temperature and flow regime. Mosses and stony substrate significantly differed in macroinvertebrate assemblages in both, pre- and post-disturbance periods. Dam closure represented the most intensive disturbance event, which caused drastic change of macroinvertebrate assemblage structure in both microhabitat types during the first two post-disturbance years: reduction of density of dominant groups such as Amphipoda, Gastropoda and dominant insects groups (Coleoptera, Ephemeroptera and Trichoptera) as well as the drastic increase of Chironomidae density, followed by density recovery of all previous groups in the second year. Samples from 2015 had the highest similarity with pre-disturbance assemblages for both microhabitat types implying partly recovered macroinvertebrate assemblages five years after dam closure. By comparing pre- and post-disturbance data, this study increases our understanding of basic ecological response to damming.

macroinvertebrates, large dam impact, Dobra River, Croatia

nije evidentirano