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Does restoration of structural heterogeneity enhance habitat availability for the bullhead (Cottus gobio) in the Glan River, Austria?

2012Does restoration of structural heterogeneity enhance habitat availability for the bullhead (Cottus gobio) in the Glan River, Austria?BASIC Tea (Croatia)
Organisation:Christian Albrechts University, Kiel (DE)Supervisor :Martin Zimmer & Josef Wanzenböck
Summary: Habitat availability is often regarded as the primary factor that limits population and community recovery in degraded ecosystems. Therefore restoration measures have been emphasized as an important ecological tool for the improvement of the physical and hydraulic environment. However, often they are not designed properly regarding the goals and the measures necessary to improve habitat availability for the target species. Evaluation of such actions is necessary to improve our understanding of the relationship between habitat enhancement and species response. This study was conducted in the heavily modified Glan River in Austria, in order to determine the success of restored river features that have been implemented in 2008 and 2011. The research focused on a small sedentary species with limited mobility, the bullhead (Cottus gobio), which represents a good indicator of structural changes, due to its strong connection with the microhabitat features. The bullhead predominately occurs in stony streams and rivers where the flow is moderate and the water is cool and oxygen-rich. However, they may also be found in lakes, not only in the stony margins, but also in the profundal zone in depths above twenty meters. To assess the habitat availability as well as the real habitat use by the species, intensive field work was organized in the summer of 2012. Two restored meanders and two channelized parts were sampled in order to determine the focal position of the individual species and to measure habitat parameters (velocity, depth, substrate, cover). In order to assess the habitat suitability at a larger spatial scale, additional sampling of the habitat availability was conducted during the summer of 2012, covering the whole restored part plus channelized reaches in between. The expected outcome would give an overview of the restoration success regarding the investigated species, in terms of habitat suitability, as well as a rough estimate of population size.