Macrozoobenthos and submerged macrophytes interact closely. However, studies in China have focused on the middle and lower reaches of the Yangtze River, where shallow lakes are concentrated, rather than on temperate lakes. To clarify the responses of taxonomic and functional groups of macrozoobenthos in temperate lakes to changes in submerged macrophyte biomass (BMₐc) on a large scale, 19 temperate lakes within Baiyangdian Lake were investigated in this study. The BMₐc differed greatly across the 19 lakes, and Potamogeton crispus was the dominant species. According to the BMₐc, the 19 lakes were divided into 4 groups. One-way analysis of variance and Pearson correlation analysis showed that the water environmental parameters were different among the 4 groups, and the BMₐc was significant correlated with all the physical and chemical parameters of water bodies (except for water depth). Forty-one taxa of macrozoobenthos were identified in the 19 lakes, with oligochaetes, Hirudinea, gastropods, crustaceans, chironomid larvae, and aquatic insects (excluding chironomid larvae) represented by 9, 1, 4, 2, 19, and 6 species, respectively. Chironomid larvae and oligochaetes dominated by density, and gastropods and chironomid larvae dominated by biomass. Canonical correspondence analysis showed that the BMₐc was the most important factor affecting the macrozoobenthos community structure in group 1 to group 4. Macrozoobenthos with low pollution tolerance values were mainly found in areas with high BMₐc, while species with high pollution tolerance values were mainly distributed in areas with low BMₐc and high nutrient contents. Different taxonomic and functional groups of macrozoobenthos responded differently to changes in BMₐc. As BMₐc increased, density and biomass of oligochaetes and chironomid larvae tended to decrease, while those of gastropods and aquatic insects tended to first decrease and then increase. Collectors had more species than any other functional group in group 1 to group 4. As BMₐc increased, density and biomass of collectors gradually decreased, while density of predators, shredders, and scrapers tended to first decrease and then increase.

There are multiple stressors derived from urbanizations that result in frequent disturbances on streams and rivers reducing water quality and threatens aquatic biota. P-glycoprotein (P-gp)-mediated multixenobiotic resistance (MXR) is a defence mechanism analogous to multidrug resistance (MDR), which has been demonstrated in several aquatic organisms. This system protects cells against the entry and the accumulation of xenobiotics and has been proposed as a biomarker for pollution assessment. We conducted a study in a post-urban reach of Esquel stream (Chubut Province) downstream a wastewater treatment plant, in order to assess the presence and activity of MXR in five freshwater macroinvertebrate species (Helobdella michaelseni, Helobdella simplex, Patagoniobdella variabilis, Hyalella curvispina and Chironomus riparius). We measured the accumulation of the model P-gp substrate rhodamine B (RB) in organisms previously exposed to pollution. Our results described the activity of the MXR system in the three species of leeches suggesting their suitability as the in vivo biomonitoring. We also identified a dependence of the transporter activity with the development stage in H. simplex, highlighting the importance of using organisms of similar size classes since it may affect observed results. Finally, we concluded that benthic freshwater macroinvertebrates possess different species-specific levels of MXR activity possibly influencing their natural distribution as well as their survival.

A 6-year laboratory study was conducted to explore the performance of the vermifilter (VF) on reducing sewage sludge. Sewage sludge was found to be reduced significantly in the VF and exhibited a better performance of sludge reduction as compared with the conventional biofilter (BF), which could be traced through the nitrogen-rich organic matter. The nitrogen stable isotope technology was applied to study the matter flow of sewage sludge in the VF process and the influence of earthworms Eisenia fetida on sewage sludge reduction. Results showed that (1) the protein material could be consumed more than the polysaccharide and lipid materials, respectively, in the VF; (2) the presence of earthworms could enhance the consumption capacity of the VF on the protein-rich material of the sewage sludge; (3) earthworms played a leading role on the nitrogen lifting of the sewage sludge, leading to the performance difference of the effluent sludge or biofilm sludge between the VF and BF; (4) in the VF, nitrogen-isotope accumulation in either biofilms or earthworms happened more significantly in the lower layer than in the upper one, while nitrogen transfer of sewage sludge happened more significantly in the upper layer than in the lower one; (5) earthworms improved the feeding environment of organisms (microorganisms in biofilms, moth fly larvae, Limacidaes, and Lymnaeidaes); (6) biofilms, Limacidaes, and moth fly larvae performed better than leeches, Lymnaeidaes, and moth fly adults at nitrogen transfer of sewage sludge.

Alpine lakes are extreme ecosystems located in remote areas and populated by few but well-adapted species. Because of their remote location, they are often considered pristine, unpolluted ecosystems. Since the 1980s, however, they have been affected by global anthropogenic impacts. Macrobenthic invertebrates play a pivotal role in these ecosystems and can be used as bioindicators also for monitoring the accumulation of trace elements. We characterized the macrobenthic invertebrates community of Balma Lake (Cottian Alps, Northwest Italy) and Dimon Lake (Carnic Alps, Northeast Italy) in summer and autumn and measured the levels of nine trace elements (As, Cd, Cr, Cu, Fe, Ni, Pb, Se, Zn) in the most abundant taxa (Chironomidae and Oligochaeta in both lakes and Hirudinea in Dimon Lake) in both seasons. The highest levels of trace elements were recorded for Fe, Cu, and Zn according to their environmental availability and their function as essential elements. The total amount of trace elements was highest for the Chironomidae from both lakes compared to the other two taxa. As, Cd, Pb, and Zn were measured in sediment to calculate bioaccumulation factor (BAF) values. The amount of elements in sediment and macrobenthic invertebrates was higher for Dimon Lake, suggesting a greater flux via precipitation of contaminants from the lowland. The BAF values were decreased with increasing trace elements concentration in sediment, indicating mechanisms of elements excretion in biota where the environment is contaminated. This study is the first to report on the use of macrobenthic invertebrates to monitor trace elements in Alpine lakes.