engleski

Macroinvertebrate community of a sub-Mediterranean temporary karst river in the Western Balkans

Temporary rivers and streams are dynamic ecosystems in which water stops flowing periodically and flows become terrestrial habitats that can contain isolated pools and lakes. Due to great temporal and spatial variability of environmental conditions, they are complex systems, thus they were poorly researched in the past. However, in recent years their importance was recognized and research efforts significantly increased. This research was conducted along a temporary karst river Krčić, situated in the sub- Mediterranean part of Croatia. Krčić is a small river, about 10 km long and it usually dries up during summer and early autumn months. It is minimally influenced by anthropogenic activities and can thus be regarded as a reference site of temporary rivers in this region. The sampling was performed in 2016 during the flowing phase ; in late spring/early summer and winter season, on the upper, middle and lower reaches. At each part of the flow three sampling sites were chosen, where triplicate D-net samples were taken. The sampling encompassed all major microhabitat types. Overall, different size fractions of lithal covered with moss dominated. However, proportion of xylal increased in the lower reaches due to the forest riparian vegetation. Aquatic macroinvertebrate community was highly abundant, however, taxa richness was relatively low and uniform along the whole course of the river. Highest diversity of macroinvertebrates was recorded in the lower reaches, due to increased habitat heterogeneity and availability of various resources. The most abundant taxa were Chironomidae, Ephemeroptera, Plecoptera and Trichoptera, thus their community composition and structure are analysed more in detail. Because of periodically occurring dry seasons, communities were dominated by generalists commonly found in perennial streams and specialists adapted to reduced water capacity or droughts. Since temporary rivers are vulnerable ecosystems, sensitive to water extraction, point and non-point pollution sources and climate change, better knowledge of aquatic and terrestrial communities is important for predicting the changes in these ecosystems and for adequate management and protection.

temporary karst river, Chironomidae, Ephemeroptera, Plecoptera, Trichoptera

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