Long-term evolution of fish communities in European mountainous rivers: past log driving effects, river management and species introduction (Salzach River, Danube)

Aquat Sci (2015) 77:395–410 DOI 10.1007/s00027-015-0398-3 Aquatic Sciences RESEARCH ARTICLE Long-term evolution of fish communities in European mountainous rivers: past log driving effects, river management and species introduction (Salzach River, Danube) Gertrud Haidvogl • Didier Pont • Horst Dolak • Severin Hohensinner Received: 17 April 2014 / Accepted: 21 May 2015 / Published online: 5 June 2015 Ó The Author(s) 2015. This article is published with open access at Springerlink.com Abstract Using historical sources from the turn of the 19th to the 20th century, we investigated the long-term evolution of the fish community in a mountainous river network and the influence of different human uses and management measures. Within the alpine Salzach catchment, historical presence was reconstructed for 26 fish species, abundance classes for 19 species. Due to channelization, flood protection and dam erections, the spatial distribution of fish species was reduced during the 20th century. Many rheophilic and eurytopic fish species historically inhabited river reaches along a wide longitudinal profile and were present in more upstream river reaches than nowadays. The decrease of species diversity in the headwater sections is a consequence of lost lateral connectivity. Strongest effects are reported for sensitive species requiring different habitat types during their life cycles (especially pike, nase, Danube salmon). One of the most important shifts from the historical fish community to the present one reflects the deliberate introduction of fish species for fisheries. Rainbow trout and brook trout, absent from the historical fish assemblage, today represent up to 29 % of the total number of fish occurrences. In contrast, log driving, one of the most common historical pressures in This article is part of the special issue ‘Historical ecology of riverine fish in Europe’. G. Haidvogl (&)
H. Dolak
S. Hohensinner Institute of Hydrobiology and Aquatic Ecosystem Management, University of Natural Resources and Life Sciences Vienna, Max Emanuelstrasse 17, 1180 Vienna, Austria e-mail: D. Pont Research Unit Hydrosystems and Bioprocesses, IRSTEA, Antony, France European mountainous rivers, did not show significant negative effects on the past fish ecological situation. This result strongly differs from the impacts of log driving and deforestation demonstrated for recent times, and could be related to the change in log driving practices during the 20th century and to the high societal value of fish before the industrialization period along with other historical pressures affecting fish in rivers without log driving. In general, our results can be valid for a large number of European mountainous rivers. They highlight the usefulness of such detailed historical studies for our understanding of the long-term evolution of fish communities and their present functioning, and point the way for future river management strategies to restore fish biodiversity. Keywords Salzach catchment
Alpine rivers
Historical ecology
Fish community changes
Log driving Introduction Rivers and their fish communities have been modified by humans for millennia to operate mills, to serve as transport routes and recipients of waste, or to harvest aquatic animals and plants. The societal impact increased since the onset of industrialization in the late 18th century. Technological inventions and a new concept of the human-nature relation went hand in hand with a shift from solar-based to fossil energy sources (Fischer-Kowalski and Haberl 2007). This resulted in an unprecedented, systematic and large-scale exploitation of natural resources along with accelerated exchange of materials and goods, as well as in new technical means to control natural processes. Considering the consequences of this development on rivers, Jakobsson 123 396 (2002) introduced the term ‘‘industrialization of rivers’’. Human uses of rivers intensified in the 19th and 20th century and they were progressively supported by new technical infrastructures and political programs (see e.g. White 1995 for an early study of the Columbia River or Castonguay and Evenden 2012; Mauch and Zeller 2008 for recent compilations about European and North American rivers). On large and medium-sized rivers, systematic channelization measures improved shipping to meet the requirements of steam ships, which started to replace wooden ships after ca. 1810. Artificial shipping channels connected river catchments and enabled biological invasions. Systematic flood protection measures started mainly in the late 19th century as a result of demographic growth and the subsequent spread of settlements and agriculture towards floodplains (Blackbourn 2007; Haidvogl 2008; Haidvogl et al. 2013). Hydropower dams altered fluvial hydromorphology and habitats in particular in the 20th century (e.g. Evenden 2004). Moreover, organic and nonorganic pollution intensified (e.g. Cioc 2002 for the Rhine). These developments were accompanied by the continued use of rivers for floating of timber and fuel wood, which affected aquatic species during the wood transport itself but also because of habitat change due to maintenance work during the year (Gingrich et al. 2012). In pre-industrial times and during the transition phase to the industrial period, fuel wood was the main energy source and local and regional supply was indispensable for private households, local crafts or mining. In the 20th century, log driving and wood floating was mainly done to supply large industries (saw mills, pulp and paper factories). In addition, biological interventions gained new momentum in the second half of the 19th century because improved transport facilities and progress in artificial reproduction technology promoted the introduction of alien fish species (e.g. Halverson 2012 for rainbow trout). The described human interventions altered riverine fish communities. The current estimate is that between 40 and 80 % of species are now imperiled in Europe; in North America the percentage is between 27 and 35 % (Helfman 2007; Kottelat and Freyhof 2007; Tockner et al. 2009). Habitat change including pollution, exploitation and species introductions are considered as important drivers (Helfman 2007). Reconstructing historical fish ecological conditions can highlight biodiversity changes and species decline as well as the associated temporal trends on the catchment or single river scale. Such studies can serve as a reference for ecological assessment, as required in Europe for example by the EU-Water Framework Directive (European Commission 2000), and as a basis for planning river restoration measures. Furthermore, historical reconstructions help investigate the fish ecological impacts of human alterations 123 G. Haidvogl et al. such as habitat change, (over-)exploitation along with intentional species introduction or unintended dislocation of species. Carrel (2002), Wolter et al. (2005) or Winte (...truncated)