Az amurgéb (Perccottus glenii Dybowski, 1877) egy álló- és egy folyóvízi populációjának táplálkozásökológiai vizsgálata

Az utóbbi két évtizedben a Távol‐Keletről származó amurgéb (Perccottus glenii) inváziója figyelhető meg Kelet‐ és Közép‐Európában. Munkánk során az amurgéb évszakonkénti részletes táplálkozásökológiai elemzését tűztük ki célul egy állóvízben (a Rakamaz-Tiszanagyfalui‐Nagy‐morotvában) és egy vízfolyásban (a Lónyay‐főcsatornában). A legjelentősebb táplálékszervezeteknek az árvaszúnyogok (Chironomidae), szitakötők (Odonata), rákok (Crustacea) és kérészek (Ephemeroptera) bizonyultak. A faj táplálkozásának intenzitásában nem tapasztalható méret, évszak és hely által befolyásolt változás. Táplálékának összetételét legfőképp a halak mérete befolyásolja, amelynek hatása erősebbnek bizonyult az élőhelyi és évszakos hatásoknál is. Kutatásaink igazolják, hogy az amurgé a vízi táplálékhálózat számos szintjét (kompartmentjét) befolyásolhatja, elsősorban azonban a makroszkopikus gerinctelen szervezetek hatékony predátora

Habitat filtering determines spatial variation of macroinvertebrate community traits in northern headwater streams

Although our knowledge of the spatial distribution of stream organisms has been increasing rapidly in the last decades, there is still little consensus about trait-based variability of macroinvertebrate communities within and between catchments in near-pristine systems. Our aim was to examine the taxonomic and trait based stability vs. variability of stream macroinvertebrates in three high-latitude catchments in Finland. The collected taxa were assigned to unique trait combinations (UTCs) using biological traits. We found that only a single or a highly limited number of taxa formed a single UTC, suggesting a low degree of redundancy. Our analyses revealed significant differences in the environmental conditions of the streams among the three catchments. Linear models, rarefaction curves and beta-diversity measures showed that the catchments differed in both alpha and beta diversity. Taxon- and trait-based multivariate analyses also indicated that the three catchments were significantly different in terms of macroinvertebrate communities. All these findings suggest that habitat filtering, i.e., environmental differences among catchments, determines the variability of macroinvertebrate communities, thereby contributing to the significant biological differences among the catchments. The main implications of our study is that the sensitivity of trait-based analyses to natural environmental variation should be carefully incorporated in the assessment of environmental degradation, and that further studies are needed for a deeper understanding of trait-based community patterns across near-pristine streams

Integrating dispersal proxies in ecological and environmental research in the freshwater realm

Dispersal is one of the key mechanisms affecting the distribution of individuals, populations, and communities in nature. Despite advances in the study of single species, it has been notoriously difficult to account for dispersal in multispecies metacommunities, where it potentially has strong effects on community structure beyond those of local environmental conditions. Dispersal should thus be directly integrated in both basic and applied research by using proxies. Here, we review the use of proxies in the current metacommunity research, suggest new proxies, and discuss how proxies could be used in community modelling, particularly in freshwater systems. We suggest that while traditional proxies may still be useful, proxies formerly utilized in transport geography may provide useful novel insights into the structuring of biological communities in freshwater systems. We also suggest that understanding the utility of such proxies for dispersal in metacommunities is highly important for many applied fields such as freshwater bioassessment, conservation planning, and recolonization research in the context of restoration ecology. These research fields have often ignored spatial dynamics and focused mostly on local environmental conditions and changes therein. Yet, the conclusions of these applied studies may change considerably if dispersal is taken into account

Effects of nonnative species on the stability of riverine fish communities

ResearchDespite the increasing ubiquity of biological invasions worldwide, little is known about the scale-dependent effects of nonnative species on real-world ecological dynamics. Here, using an extensive time series dataset of riverine fish communities across different biogeographic regions of the world, we assessed the effects of nonnative species on the temporal variability and synchrony in abundance at different organizational levels (population, metapopulation, community and metacommunity) and spatial scales (stream reach and river basin). At the reach scale, we found that populations of nonnative species were more variable over time than native species, and that this effect scaled up to the community level – significantly destabilizing the dynamics of riverine fish communities. Nonnative species not only contributed to reduced community stability, but also increased variability of native populations. By contrast, we found no effect of nonnative species dominance on local interspecific synchrony among native species. At the basin scale, nonnative metapopulations were again more variable than the native ones. However, neither native metapopulations nor metacommunities showed differences in temporal variability or synchrony as nonnative species dominance increased basin-wide. This suggests a ‘dilution effect’ where the contribution to regional stability of local native populations from sites displaying low levels of invasion reduced the destabilizing effects of nonnative species. Overall, our results indicate that accounting for the destabilizing effect of nonnative species is critical to understanding native species persistence and community stabilityinfo:eu-repo/semantics/publishedVersio

Effects of a Nuclear Power Plant Warmwater Outflow on Environmental Conditions and Fish Assemblages in a Very Large River (the Danube, Hungary)

Direct or indirect effects of nuclear power plants' (NPPs) warmwater effluents on the structure of biotic assemblages are poorly known in very large rivers. We examined changes in physical habitat structure, temperature condition and their possible effects on the structure of Danubian fish assemblages due to the outflow of the Paks NPP's warmwater channel, in Hungary. Seasonal surveys conducted both upstream and downstream from the outfall showed that its hydromorphological effects were generally local and comparable to natural or other anthropogenic hydromorphological changes. The effect of the returned cooling water was more apparent in the seasonally recorded surface water temperatures and depended highly on the spatial positioning of the sampling sites. However, environmental and spatial variables accounted only for a low amount of variance in case of both shoreline and offshore fish assemblage data. Overall, we found that the outflow exerted only a local scale effect on the structure of Danubian fish assemblages. Rather, fish assemblages varied largely both inshore and offshore, which dynamics overruled any effects of the artificially elevated temperature. Our study highlights the importance of the assessment of hydrogeomorphological variability of rivers and their influence on fish assemblage variability when examining spatial effects of thermal pollution

Restricted by borders: trade-offs in transboundary conservation planning for large river systems

Effective conservation of freshwater biodiversity requires accounting for connectivity and the propagation of threats along river networks. With this in mind, the selection of areas to conserve freshwater biodiversity is challenging when rivers cross multiple jurisdictional boundaries. We used systematic conservation planning to identify priority conservation areas for freshwater fish conservation in Hungary (Central Europe). We evaluated the importance of transboundary rivers to achieve conservation goals by systematically deleting some rivers from the prioritization procedure in Marxan and assessing the trade-offs between complexity of conservation recommendations (e.g., conservation areas located exclusively within Hungary vs. transboundary) and cost (area required). We found that including the segments of the largest transboundary rivers (i.e. Danube, Tisza) in the area selection procedure yielded smaller total area compared with the scenarios which considered only smaller national and transboundary rivers. However, analyses which did not consider these large river segments still showed that fish diversity in Hungary can be effectively protected within the country’s borders in a relatively small total area (less than 20 % of the country’s size). Since the protection of large river segments is an unfeasible task, we suggest that transboundary cooperation should focus on the protection of highland riverine habitats (especially Dráva and Ipoly Rivers) and their valuable fish fauna, in addition to the protection of smaller national rivers and streams. Our approach highlights the necessity of examining different options for selecting priority areas for conservation in countries where transboundary river systems form the major part of water resources.Full Tex

Advances in Understanding Environmental Risks of Red Mud After the Ajka Spill, Hungary

In the 5 years since the 2010 Ajka red mud spill (Hungary), there have been 46 scientific studies assessing the key risks and impacts associated with the largest single release of bauxite-processing residue (red mud) to the environment. These studies have provided insight into the main environmental concerns, as well as the effectiveness of remedial efforts that can inform future management of red mud elsewhere. The key immediate risks after the spill were associated with the highly caustic nature of the red mud slurry and fine particle size, which once desiccated, could generate fugitive dust. Studies on affected populations showed no major hazards identified beyond caustic exposure, while red mud dust risks were considered equal to or lesser than those provided by urban dusts of similar particle size distribution. The longer-term environmental risks were related to the saline nature of the spill material (salinization of inundated soils) and the release and the potential cycling of oxyanion-forming metals and metalloids (e.g., Al, As, Cr, Mo, and V) in the soil–water environment. Of these, those that are soluble at high pH, inefficiently removed from solution during dilution and likely to be exchangeable at ambient pH are of chief concern (e.g., Mo and V). Various ecotoxicological studies have identified negative impacts of red mud-amended soils and sediments at high volumes (typically [5 %) on different test organisms, with some evidence of molecularlevel impacts at high dose (e.g., genotoxic effects on plants and mice). These data provide a valuable database to inform future toxicological studies for red mud. However, extensive management efforts in the aftermath of the spill greatly limited these exposure risks through leachate neutralization and red mud recovery from the affected land. Monitoring of affected soils, stream sediments, waters and aquatic biota (fungi, invertebrates and fish) have all shown a very rapid recovery toward prespill conditions. The accident also prompted research that has also highlighted potential benefits of red mud use for critical raw material recovery (e.g., Ga, Co, V, rare earths, inform), carbon sequestration, biofuel crop production, and use as a soil ameliorant

How natural capital delivers ecosystem services: a typology derived from a systematic review

There is no unified evidence base to help decision-makers understand how the multiple components of natural capital interact to deliver ecosystem services. We systematically reviewed 780 papers, recording how natural capital attributes (29 biotic attributes and 11 abiotic factors) affect the delivery of 13 ecosystem services. We develop a simple typology based on the observation that five main attribute groups influence the capacity of natural capital to provide ecosystem services, related to: A) the physical amount of vegetation cover; B) presence of suitable habitat to support species or functional groups that provide a service; C) characteristics of particular species or functional groups; D) physical and biological diversity; and E) abiotic factors that interact with the biotic factors in groups A–D. ‘Bundles’ of services can be identified that are governed by different attribute groups. Management aimed at maximising only one service often has negative impacts on other services and on biological and physical diversity. Sustainable ecosystem management should aim to maintain healthy, diverse and resilient ecosystems that can deliver a wide range of ecosystem services in the long term. This can maximise the synergies and minimise the trade-offs between ecosystem services and is also compatible with the aim of conserving biodiversity