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Several studies have indicated the presence of contaminants in Alpine aquatic ecosystems. Even if measured concentrations are far below those that cause acute effects, continuous exposure to sub-lethal concentrations may have detrimental effects on the aquatic species present in these remote environments. This may lead to a cascade of indirect effects at higher levels of the ecological hierarchy (i.e., the community). To improve the determination of ecologically relevant risk endpoints, behavioural alterations in organisms due to pollutants are increasingly studied in ecotoxicology. In fact, behaviour links physiological function with ecological processes, and can be very sensitive to environmental stimuli and chemical exposure. This is the first study on behavioural alteration in a wild population of an Alpine species. In the present study, a video tracking system was standardized and subsequently used to identify contaminant-induced behavioural alterations in Diamesa zernyi larvae (Diptera, Chironomidae). Diamesa zernyi larvae, collected in an Italian Alpine stream (Rio Presena, Trentino Region), were acclimated for 24 h and successively exposed to several aquatic contaminants (pesticides: chlorpyrifos, metolachlor, boscalid, captan; pharmaceuticals: ibuprofen, furosemide, trimethoprim) at concentrations corresponding to their Lowest Observed Effect Concentration (LOEC). After 24, 48, 72, and 96 h of exposure, changes in the distance moved, the average speed, and the frequency of body bends were taken to reflect contaminant- and time-dependent effects on larval behaviour. In general, metolachlor, captan, and trimethoprim tended to reduce all the endpoints under consideration, whereas chlorpyrifos, boscalid, ibuprofen, and furosemide seemed to increase the distances moved by the larvae. This could be related to the different mechanisms of action of the investigated chemicals. Independently of the contaminant, after 72 h a general slowing down of all the behavioural activities occurred. Finally, we propose a behavioural stress indicator to compare the overall behavioural effects induced by the various contaminants. [ABSTRACT FROM AUTHOR]

• Chironomid local species richness (LSR) in European rivers is strongly impacted. • Depth, substrate index and velocity are primary environmental factors of the impact. • Habitat species richness (HSR) is stronger than each of the factors. • Correlations between α, β, and γ diversity assess seasonal assemblage stability. • Biotic mechanisms confer a greater stability in autumn than in any other season. Multiscale determinants of riverine chironomid species richness were assessed in seven rivers in Central Poland, an area representative of the European temperate climatic zone. The impact of environmental factors, seasonality, as well as the concepts of gamma diversity, i.e. habitat species richness (HSR), alpha diversity, i.e. local species richness (LSR), and the relationships between these, i.e. beta diversity, were studied. One site in each river was defined as a habitat and monthly LSR time series data were obtained at each site over a full annual cycle for analysis. No strong trend in the time series was detected. The autocorrelation function (ACF) indicated that the time series were uncorrelated white noise. A stepwise forward regression model with no HSR indicated that depth, Substrate Index (SI), velocity and dissolved oxygen were significant factors of LSR values in the studied area, explaining together with summer (as a dummy variable) 67.01% of LSR variance (R2 adj = 0.66). Seasonality was noticeable in the impact of summer on increase in species richness. When HSR was included in a similar model then it explained, together with benthic particulate organic matter (BPOM), SI, depth, and velocity, 70.90% of variability in LSR variance (R2 adj = 0.69), HSR alone accounting for 58.95% in LSR variance (R2 adj = 0.59). In both the annual cycle and in given seasons, HSR strongly positively correlated with the minimum, maximum, and mean LSR values, and there was no saturation of the rivers by chironomid species, i.e. other chironomid species were still able to inhabit the rivers beside the present ones. HSR did not correlate with beta diversity when measured by two widely used setwise beta diversity indices, or by three pairwise beta diversity indices. The exception was in autumn, where one setwise and two pairwise beta diversity measures correlated with both alpha and gamma diversity measures, which suggests a greater stability of larval chironomid assemblages in that season. This larval stability was not associated with greater stability of environmental factors in autumn, hence the stability seems to be related to undisclosed biotic mechanisms. Seasonality was also a strong factor in predicting the exchange of species. Turnover index between seasons ranged from 0.133 (spring vs summer) to 0.261 (autumn vs winter) and UPGMA clustering determined least chironomid similarity between winter and other seasons. [ABSTRACT FROM AUTHOR]

Abstract: Members of the families Chironomidae (chironomids or non-biting midges), Ceratopogonidae (ceratopogonids or biting midges) and Simuliidae (simulids or blackflies) are ubiquitous dipterans of the infraorder Culicomorpha. They are extremely diversified in ecological strategies. Their larvae play major roles in aquatic food webs as detritivores or predators, whereas their adults can be general predators (Chironomidae), hemolymphagous or hematophagous predators (Ceratopogonidae and Simuliidae) or pollinators. Both larval and adult stages are commonly infected by bacteria, viruses, protists, nematodes, true fungi and oomycetes. These phylogenetically diverse assemblages of microorganisms can simultaneously infect multiple species of chironomids, ceratopogonids and simulids, and each host may become trophically interrelated with other hosts by sharing their parasites. Here, we review the information on fungal and oomycete parasites of these dipteran groups with special reference to the natural regulation of host populations, the impact of parasitism in food webs, and the potential of these parasites as biocontrol agents. [Copyright &y& Elsevier]

Abstract: Non-biting midges (Chironomidae, Diptera) are widely distributed aquatic insects. The short-living chironomid adults swarm in large numbers above water surfaces, and are sometimes considered a nuisance. They are vectors of certain bacteria, and have a key-role in benthic ecosystems. Optical cues, involving reflection-polarization from water, were found to be important in the habitat selection by three Mediterranean freshwater chironomid species. In this work we report on our multiple-choice experiments performed in the field with several other European freshwater chironomid species. We show that the investigated non-biting midges are positively polarotactic and like many other aquatic insects their females are attracted to horizontally polarized light. Our finding is important in the visual ecology of chironomids and useful in the design of traps for these insects. [Copyright &y& Elsevier]

This paper presents a late Holocene chironomid-inferred record of July air temperature from a core obtained from Lake Uddelermeer in the Netherlands. The core interval, which dates from 2500 to 400 cal. yr. BP, was analysed at multi-decadal resolution for organic content, pollen, spores and NPPs (Non Pollen Palynomorphs), and chironomid head capsules. These proxies indicate that, from 2500 to 1140 cal. yr. BP, the lake was mesotrophic and sustained a Littorellion community, while the chironomid assemblage was dominated by littoral species associated with macrophytes. At 1140 cal. yr. BP, a shift in the lake ecology occurred from low-nutrient to high-nutrient conditions dominated by algae. This shift might be linked to a concurrent increase in human impact and is reflected in the chironomid assemblage by increases in eurytopic taxa, which are resistant to disturbances. Shifts in the chironomid record between 2500 and 1140 cal. yr. BP do not coincide with changes in lake ecology and are presumably driven by climate change. Using a Norwegian-Swiss calibration dataset as a modern analogue, we produced a chironomid-inferred temperature (C-IT) reconstruction. This reconstruction compares well to other regional temperature reconstructions in timing and duration showing a Roman Warm Period between 2240 and 1760 cal. yr. BP, a Dark Age Cold Period starting at 1760 cal. yr. BP and the Medieval Climate Anomaly beginning at 1280 cal. yr. BP. The C-IT record indicates a temperature drop of 1.5 °C from the Roman Warm Period to the Dark Age Cold Period. Findings improve knowledge of the first millennium AD in NW Europe, which was characterised by changes in landscape, vegetation, society and climate. • We present a late Holocene multi-proxy, multi-decadal reconstruction of lake ecology from lake Uddelermeer, the Netherlands • Proxies show a change from mesotrophic to eutrophic conditions at 1140 cal. yr. BP. • Minor shifts in chironomids, between 2500 to 1140 cal. yr. BP, coincide with climatic phases. • A 1.5°C fall in temperature from the Roman Warm Period to the Dark Age Cold Period is recorded. [ABSTRACT FROM AUTHOR]

Propsilocerus akamusi (Diptera: Chironomidae) is a dominant macroinvertebrate species in many eutrophic lakes in subtropical and temperate zones. P. akamusi larvae can migrate deep into the sediment (>30 cm) during summer where is no oxygen. However, to our knowledge, the specific adaptive tactics of its tube-dwelling life (>30 cm) and underlying mechanisms why this species is favored by nutrient-rich lakes remain limited. With the understanding above-mentioned issues, we can provide important information for the development of sensitive biomonitoring. We examined monthly morphological dynamics and physiological adaptations of P. akamusi to anoxic conditions, and environmental relationships of the species abundance in a subtropical eutrophic lake. Results of our experiments indicated that this species presented extremely low fuel consumption at a state of estivation when the larvae dwelt in deep sediment, and conducted anaerobic respiration, with ethanol as a major metabolite, to withstand long term anoxic conditions. Additionally, in our field study, the abundance of P. akamusi correlated positively with most nutrient-related variables, indicating that this species can serve as sentinel organisms of nutrient enrichment. We suggest that the high tolerance to anoxia and detritivorous diet of P. akamusi larvae may allow the species to benefit from nutrient enrichment. The vertical niche differentiation and the avoidance of benthivorous predator by vertical sediment migration behavior may also contribute to its high dominance in eutrophic freshwaters. [ABSTRACT FROM AUTHOR]