摘要：Since 2006 the upper part of the Myjava River has undergone strong changes. Above
the monitoring site Myjava NAD (rkm 72.6) a water reservoir was rebuilt to a dry
polder in 2006 and the stagnant water has changed into realined channel of the Myjava
River. Because of benthic invertebrates has not been monitored at this locality
since 2010 we would like to evaluate changes of macrozoobenthos communities at
the sampling site Myjava NAD in present and compare them with the sampling site
which is relatively undisturbed. This reference site (hypocrenal) is situated in the
beech forest at rkm 82. We assessed physico-chemical parameters, hydromorphology
using River Habitat Survey at both localities in 2014 – 2015. Macrozoobenthos
was sampled by kicking technique in spring and in autumn 2014 – 2015. The aim of
our research was to: 1. Evaluate hydromorphology of selected stream sites; 2. Find
out macrozoobenthos structure at these sampling sites 3. Compare changes in metrics
found out during monitoring in 2003 – 2013 with our data from 2014. The PCA
showed that the structure of macrozoobenthos is influenced first of all by the hydromorphological
features of the Myjava River and the physico-chemicals parameters
had less influence. Metrics calculated from macrozoobenthos abundance of the
site Myjava NAD from the years 2003, 2014, 2015 showed that biological status is
better but the site is hydromorphologicaly disturbed and therefore it belongs to the
HMWB. According to the ecological evaluation we found out that the sampling site
in the beech forest has a character of a reference site therefore it is unique in the
Myjava River basin. Occurrence of the protected species Cordulegaster heros, sensitive
species Ibisia marginata and Ephemera danica was threatened by the clearcutting
in 2015. We suggest to minimalize human impact in the vicinity of the stream
at this valuable part of the Myjava River.
