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Chironomus riparius Meigen were exposed to three different insecticides, the organophosphorous fenitrothion and the carbamates carbaryl and carbofuran (0, 1, 10, and 100 mg/L) for 24 h as fourth-instar larvae. Acetylcholinesterase (AChE), naphtylacetate esterase (NAE), p-nitrophenylacetate esterase (PNPAE), glutathione-S-transferase (GST), and a number of metabolites (alanine, pyruvate, lactate, trehalose, aspartate, oxalacetate) were measured to determine which was the most valuable biochemical biomarker of exposure. AChE activity was significantly reduced by all three insecticides, PNPAE by fenitrothion, carbofuran and carbaryl, whereas NAE activity was stimulated by carbaryl and unaffected by fenitrothion and carbofuran. Metabolites analysis revealed a strong accumulation of alanine in larvae exposed to fenitrothion, but not in larvae exposed to carbamates. This accumulation was accompanied by a significant increase of lactate and a significant decrease of pyruvate and trehalose. No variations were observed with carbofuran and carbaryl. No change of aspartate concentration was detected. We conclude that the association of alanine accumulation with a significant inhibition of AChE activity can be used as a valuable biochemical biomarker of exposure.

Semiaquatic organisms depend on the features of both water bodies and landscapes; the interplay between terrestrial and aquatic systems might influence the semiaquatic communities, determining the scale at which management would be more effective. However, the consequences of such interplay are not frequently quantified, particularly at the community level. We analyzed the distribution of amphibians to evaluate whether the influence of landscape features on freshwater ecosystems can have indirect consequences at both the species and community level. We surveyed 74 streams in northern Italy to obtain data on breeding amphibians, water, and microhabitat features; we also measured features of surrounding landscapes. We used an information-theoretic approach and structural equation models to compare hypotheses on causal relationships between species distribution and variables measured at multiple levels. We also used a constrained redundancy analyses to evaluate causal relationships between multivariate descriptors of habitat features and community composition. Distribution of Salamandra salamandra was related to landscape, hydrological, and water characteristics: salamanders were more frequent in permanent streams with low phosphate concentration within natural landscapes. Water characteristics were dependent on landscape: streams in natural landscapes had less phosphates. Landscape influenced the salamander both directly and indirectly through its influence on phosphates. Community structure was determined by both landscape and water characteristics. Several species were associated with natural landscapes, and with particular water characteristics. Landscape explained a significant proportion of variability of water characteristics; therefore it probably had indirect effects on community. Upland environments play key roles for amphibians, for example, as the habitat of adults, but upland environments also have indirect effects on the aquatic life stages, mediated thro

Macroinvertebrates are one of the key components of lake ecosystems and are required to be monitored alongside other biological groups to define ecological status according to European Union legislation. Macroinvertebrate communities are highly variable and complex and respond to a diverse

The aim of this study was to analyze the relationship between the surface development of pupal thoracic horn and adaptation to low oxygen concentration in different species of chironomids. A total of 773 samples of larvae were collected in lakes and streams together with measurements of dissolved oxygen and collection of pupal exuviae. The area of the base of the thoracic horn (ring organ, RO) and abdomen length (ABD) of pupae were measured in forty-eight species of Chironomini. RO was significantly correlated with ABD, therefore, the ratio of ring organ/abdomen length (ROA) was calculated to provide a measure less dependent on body size. Chironomus plumosus Linnwus, Chironomus riparius Meigen and Glyptotendipes pallens (Meigen) had the highest ROA, Microtendipes britteni (Edwards), Paralauterbomiella nigrohalteralis (Malloch) and Pseudochironomus prasinatus (Stxger) had the lowest ROA. ROA was still correlated with ABD, so residuals from the regression line (RROA) between RO and ABD were also calculated. An examination of the residuals revealed that some species (C riparius, Cladopelma virescens (Meigen) and Einfeldia pagana (Meigen)) had a RO larger, whereas other species (M. britteni, P. prasinatus and Stenochironomus gibbus (Fabricius)) had a RO smaller than predicted by regression with ABD. RO was significantly correlated with the 25(th) percentile of dissolved oxygen (PCTL) measured in conjunction with benthic macroinvertebrates samples. Hemoglobin concentrations measured in six species were not correlated with ABD and RO, a high hemoglobin content was measured both in small species with a small RO (Polypedilum nubeculosum (Meigen)) and in large species with a large RO (G. pallens). The ring organ is proposed as a morphological trait useful to indicate oxygen concentration in the environment, while other factors such as hemoglobin content are also likely to affect the species ability to respond to oxygen shortage.

The relationship between benthic macroinvertebrates and environmental variables from 42 Italian lakes were analysed with the aim of developing a biotic index. In the investigated lakes, 570 species were found of which 373 belonged to the family of Chironomidae and 85 to the class of oligochaeta. Rare species, those present in less than 10 samples, were excluded from the analysis, leaving 57 species for data analysis. Multivariate analysis: canonical correlation analysis (CANON) and multivariate analysis of variance and covariance (MANCOVA) were carried Out OD a large database of 1060 sampling points, for which both environmental data (16 chemical and morphometric variables) and 57 species counts from soft bottom samples were available. In addition, a second dataset of 94 sites from small lakes sampled in 2005 in Northern Italy (Lombardy), was analysed for comparison. The data analysis (CANON) from the large database gave the following results: (1) the first canonical variate was related to conductivity, pH and alkalinity and accounted for 17% of the total variation; (2) the second canonical variate was related to total phosphorus, N-NH4 and dissolved oxygen, and accounted for 15% of the total variation; (3) lake maximum depth, volume and water temperature were related to the third canonical variate, which accounted for 14% of the source of variation. The analysis of the database from small lakes revealed that in the plane of the first two canonical variates dissolved oxygen was inversely correlated with the depth of sampling and that the second canonical variate showed an inverse relationship between transparency and nutrients. MANCOVA found evidence for differences between lake types and sampling years, confirmed the CANON results and allowed the quantification of the contribution of different target variables on species composition. A trophic status index was calculated ranking percentage oxygen saturation (O-2 %sat), transparency (transp) and total phosphorus (TP

Benthic macroinvertebrates are an essential component of freshwater environments. The ecotoxicological risk of benthic communities, estimated through the assay of biochemical markers, can be used as an early warning signal for environment alterations. In this work the activities of a number of enzymes, regarded as potential biomarker of exposure to pollutants (catalase, acetylcholinesterase, glutathione-S-transferase) was determined in homogenates of whole organisms. Specimens were collected in the rivers Taro and Ticino, northern Italy, in stony bottom reaches in five and three stations respectively. The orders of aquatic Insects Diptera, Plecoptera, Odonata, Ephemeroptera and Trichoptera, the Crustacea Amphipoda, and Annelida Oligochaeta were examined. Additional enzymes, such as NADP-dependent malate dehydrogenase, isocitric dehydrogenase, glucose-6-phosphate dehydrogenase, alcohol dehydrogenase, and lactate dehydrogenase were considered in the study. Results emphasize significant differences among taxa concerning the specific activity of most enzymes.

Leucine uptake into membrane vesicles from larvae of the midge Chironomus riparius was studied. The membrane preparation was highly enriched in typical brush border membrane enzymes and depleted of other membrane contaminants. In the absence of cations, there was a stereospecific uptake of L-leucine, which exhibited saturation kinetics. Parameters were determined both at neutral (Km 33 ± 5 mM and Vmax 22.6 ± 6.8 pmol/ 7s/mg protein) and alkaline (Km 46 ± 5 mM and Vmax 15.5 ± 2.5 pmol/7s/mg protein) pH values. At alkaline pH, external sodium increased the affinity for leucine (Km 17 ± 1 mM) and the maximal uptake rate (Vmax 74.0 ± 12.5 pmol/7s/mg protein). Stimulation of leucine uptake by external alkaline pH agreed with lumen pH measurements in vivo. Competition experiments indicated that at alkaline pH, the transport system readily accepts most L-amino acids, including branched, unbranched, and a-methylated amino acids, histidine and lysine, but has a low affinity for phenylalanine, b-amino acids, and N-methylated amino acids. At neutral pH, the transport has a decreased affinity for lysine, glycine, and a-methylleucine. Taken together, these data are consistent with the presence in midges of two distinct leucine transport systems, which combine characters of the lepidopteran amino acid transport system and of the sodium-dependent system from lower neopterans.