István Czeglédi

Non-native fish species in Hungarian waters: historical overview, potential sources and recent trends in their distribution

Due to its central position in the Danube basin and its considerable fishery sector, Hungary plays a key role in the spread of non-native fish species in Europe. Nevertheless, the status of non-native fish has not yet been reviewed for Hungary. Therefore, our aims were (1) to give a comprehensive historical overview regarding the occurrence of non-native fish species of Hungary, (2) to show their recent distribution patterns using GIS, and (3) to evaluate the importance of the possible drivers in their spread. Literature data show 59 non-native fish species from Hungary. The appearance of new species—mostly due to aquarium fish releases—shows an accelerating trend nowadays. Although non-native fish have appeared at 78.7% of the studied 767 sites during our recent countrywide survey, their distribution was uneven. Lowland streams, lowland rivers, and the River Danube were the most affected by non-native fish, particularly the gibel carp, topmouth gudgeon and pumpkinseed escaped from fish/angling ponds, and the recent invasion of Ponto-Caspian gobies. Our results indicated that in order to reduce the effects and intensity of further invasions, more rigorous control of aquarium trade, angling pond stockings, and inter-watershed fish transports are necessary.

Phylogenetic evidence for a new species of Barbus in the Danube River basin.

Three species of small-sized rheophilic Barbus fishes are endemic to and widely distributed throughout the mountain regions in the Danube River basin. In Hungary, barbels referred to as B. petenyi occur in streams in the foothills of the Carpathians near the borders with Slovakia, Ukraine and Romania. However, up to now, no genetic investigations were carried out on rheophilic barbels in this region. This study aims to clarify the taxonomic identity and distribution of the rheophilic barbels in the Hungarian plain based on molecular and morphological analyses. Two mitochondrial genes (cytochrome b, ATPase 6/8) and one nuclear gene (beta-actin intron 2) were sequenced and several morphometric and meristic characters were recorded. Phylogenetic and morphological analyses revealed that there are four genetically distinct lineages among the rheophilic barbels in the Carpathian Basin. The results demonstrated that North-Hungarian Barbus populations belong to B. carpathicus and that B. petenyi presumably does not occur in Hungary. As expected, B. balcanicus was only recorded in samples from the Balkans analyzed for reference. A distinct species, new to science, was discovered to be present in Sebes-Körös River (Crişul Repede) in eastern Hungary and western Romania and is formally described here as B. biharicus Antal, László, Kotlík - sp. nov.

The scales of variability of stream fish assemblages at tributary confluences

Tributary confluences play an important role in the dispersal of organisms, and consequently, in shaping regional scale diversity in stream networks. Despite their importance in dispersal processes, little is known about how ecological assemblages are organized in these habitats. We studied the scales of variability of stream fish assemblages over three seasons using a hierarchical sampling design, which incorporated three tributaries, three sites at the mouth of each tributary and using four sampling units at each site. We found strong scale dependent variability in species richness, composition and relative abundance. Most of the variation was accounted for by the interactive effect of season, between stream and between site effects, while habitat structure of the sampling units had a relatively minor role. Species richness showed a continuous decrease from the mainstem river in most cases, while species composition and relative abundance changed less consistently along the longitudinal profile. Consequently, we found that not only the junctions presented a strong filter on the species pool, but some species were filtered out if they passed this critical habitat bottleneck. In addition, spatial position of the tributaries along the river also contributed to assemblage variability in the confluences. Overall, our results suggest high variability in fish assemblages across multiple scales at tributary confluences. Environmental management should take a more critical care on the filtering role of tributary confluences in species dispersal, for better understanding patterns and processes in the branches of dendritic stream networks.

A unified model for optimizing riverscape conservation

1. Spatial prioritization tools provide a means of finding efficient trade-offs between biodiversity protection and the delivery of ecosystem services. Although a large number of prioritization approaches have been proposed, most are specifically designed for terrestrial systems. When applied to river ecosystems, they often fail to adequately account for the essential role that landscape connectivity plays in maintaining both biodiversity and ecosystem services. This is particularly true of longitudinal connectivity, which in many river catchments is highly altered by the presence of dams, stream-road crossings, and other artificial structures. 2. We propose a novel framework for coordinating river conservation and connectivity restoration. We formulate an optimization model for deciding which subcatchments to designate for ecosystem services and which to include in a river protected area (RPA) network, while also deciding which existing river barriers to remove in order to maximize longitudinal connectivity within the RPA network. In addition to constraints on the size and makeup of the RPA network, the model also considers the suitability of sites for conservation, based on a biological integrity index, and connectivity to multiple habitat types. We demonstrate the usefulness of our approach using a case study involving four managed river catchments located in Hungary. 3. Results show that large increases in connectivity-weighted habitat can be achieved through targeted selection of barrier removals and that the benefits of barrier removal are strongly depend on RPA network size. We find that (i) highly suboptimal solutions are produced if habitat conservation planning and connectivity restoration are done separately and (ii) RPA acquisition provides substantially greater marginal benefits than barrier removal given limited resources. 4. Synthesis and applications. Finding a balance between conservation and ecosystem services provision should give more consideration to connectivity restoration planning, especially in multi-use riverscapes. We present the first modelling framework to directly integrate and optimize river conservation and connectivity restoration planning. This framework can help conservation managers to better account for connectivity, resulting in more effective catchment scale maintenance of biological integrity and ecosystem services delivery.

Habitat mapping of riverine fish by means of hydromorphological tools: Habitat mapping of riverine fish by means of hydromorphological tools

Department of Hydraulic and Water Resources Engineering, Budapest University of Technology and Economics, Budapest, Hungary MTA‐BME Water Management Research Group, Budapest, Hungary MTA Centre for Ecological Research, Danube Research Institute, Budapest, Hungary Duna‐Ipoly National Park Directorate, Budapest, Hungary MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary Correspondence Sándor Baranya, Budapest University of Technology and Economics, Department of Hydraulic and Water Resources Engineering, Műegyetem rkp. 3, Budapest 1111, Hungary. Email: baranya.sandor@epito.bme.hu

Do diel variations in stream fish assemblages depend on spatial positioning of the sampling sites and seasons

The effect of diel period (i.e. day vs night) and its dependence on the spatial position of the sampling site were evaluated on the assessment of fish assemblage attributes in a wadeable lowland stream (Hajagos stream, Hungary). Species richness, composition and abundance data of two 150 m long reaches, one situated directly at the tributary mouth and one 6 km upstream were compared using three pass removal by electrofishing in three seasons (summer, autumn and spring) to test the effect of spatial position on day and night patterns. No differences in any assemblage level variables were found between day and night. Although fish assemblages showed large temporal variations, spatial position of the sampling site had the most influential effect on fish assemblage attributes compared with seasonal and/ or day night patterns. Consequently, the diel period had rather negligible effect in the studied stream. Daytime electrofishing data seems to be highly representative for the accurate assessment of fish assemblages in relatively small (less than 5 m wide) wadeable streams and maybe used reliably for any model of community organization (e.g. food web studies).