Lethal and Sublethal Responses of Hydropsyche pellucidula (Insecta, Trichoptera) to Commercial Polypropylene Microplastics after Different Preconditioning Treatments

Microplastics (MPs) pose biological and chemical hazards in aquatic and terrestrial food webs across the globe. Research on microplastic contamination has long focused on marine ecosystems, whereas the toxicological impact on freshwater organisms is still little explored. In this study, the lethal and sublethal response of the freshwater macroinvertebrate Hydropsyche pellucidula exposed to polypropylene MPs after different pre-conditioning treatments was assessed. Field samples were collected in a riverine system (Vipacco river; northeast Italy) to assess the characteristics of the MPs in the aquatic environment Both water and sediment were contaminated by MPs (3.73 ± 2.11 items m−3 per min and 3.33 ± 4.16 items dm−3, respectively). The chemical MPs composition included polystyrene, polyethylene terephthalate, polyurethane, polyamide, polypropylene, and polyethylene. Polypropylene (PP), although not the most abundant polymer recorded in the study area, was preferred over the other types according to its abundance in freshwater and H. pellucidula feeding behavior. A housing test was performed to recreate the natural conditions of larvae sampled for a reliable response to the ecotoxicological tests. The microplastics underwent either preconditioning with Vipacco River water (PP-river) and surfactant Triton X-100 (PP-sf) or no pre-treatment (PP). Submersion of microplastics in 10 µg L−1 of surfactant solution for 24 h was sufficient to induce consistent spectral changes and modify the chemical profile of the plastic surface. Mortality rate differed according to treatment: PP and PP-river > positive control > PP-sf > negative control. Integrated biomarker response (IBRv2) and analysis of oxidative stress biomarker levels showed a greater response of superoxide dismutase and lipid peroxidation (malondialdehyde) in larvae treated with PP conditioned in surfactant. Our findings enhance knowledge on the toxicity of PP and conditioning phases on H. pellucidula larvae.This research received no external funding.Peer reviewe

Biodiversity and Litter Breakdown in a Karstic Freshwater System (Doberdò Lake, Northeast Italy) in Relation to Water Level Fluctuations and Environmental Features

6The present study reports seasonal data about chemico-physical trends, macrobenthic invertebrates, and Phragmites australis decomposition rates within a karstic freshwater system in the western classic Karst. Results presented herein were compared with those obtained from the same system five years ago. Chemico-physical data showed higher temperatures and lower levels of pH and conductivity than in the past. The macrobenthic invertebrate community varied through the seasons and through the years, though they are dominated by few taxa, such as Asellus and Gammarus. These shredders were the most abundant functional feeding guild, playing a pivotal role in the decomposition of the vegetal organic matter. Decomposition rates k ranged between 0.009 and 0.016 days−1 and varied seasonally. k values were different from those previously reported for the investigated system. Differences are mainly due to changes in water supply, depending on decreasing rainfall regimes and hydrometric levels of the Soˇca River, which showed lower levels than in the previous study. Changes in water supply altered the fluctuating pulse that is typical of ephemeral karstic lakes, changing the system dynamics. Potential effects of climate change on local scale are also discussed.noneopenMarco Bertoli, Davide Lesa, Alessia Merson, Paolo Pastorino, Marino Prearo, Elisabetta PizzulBertoli, Marco; Lesa, Davide; Merson, Alessia; Pastorino, Paolo; Prearo, Marino; Pizzul, Elisabett

PRESENZA DI MICROPLASTICHE E ALTRI INQUINANTI NELLA COMUNITA’ ITTICA DEL FIUME VIPACCO (FRIULI VENEZIA GIULIA, NORDEST ITALIA)

L’inquinamento da microplastiche rappresenta una tra le più dannose forme di impatto che caratterizzano l’Antropocene ed esse vengono ormai rinvenute in tutti gli ecosistemi acquatici, dai laghi alpini alle profondità marine. In virtù delle loro ridotte dimensioni, esse possono essere ingerite da organismi quali macroinvertebrati e pesci, con effetti negativi che possono riguardare il sistema digerente, la riproduzione, l’induzione di stress ossidativo, fino alla morte. Inoltre, l’ingestione di microplastiche da parte degli organismi è legata a fenomeni di bioaccumulo ed esse possono aumentare l’impatto dovuto ad altre sostanze inquinanti, quali ad esempio i contaminanti organici. In questo contesto è stato ritenuto d’interesse indagare il contenuto in microplastiche a carico della comunità ittica in un fiume del Nordest Italia (Fiume Vipacco, Friuli Venezia Giulia). Cinque esemplari appartenenti a specie afferenti a diversi ruoli trofici sono stati sacrificati per analizzare la presenza di microplastiche nelle diverse trophic guilds. Le analisi si sono poi concentrate sulla specie aliena invasiva Silurus glanis, che rappresenta uno dei principali top predators per l’ambiente indagato e riveste particolare interesse per lo studio del bioaccumulo di questo ed altri inquinanti. A tale proposito è stata indagata la presenza di contaminanti organici (PCB) e idrocarburi policiclici aromatici (PAH) nei tessuti della specie ed è stato investigato lo stato sanitario. Il presente lavoro si inserisce in un progetto più ampio, che si prefigge di analizzare la presenza delle microplastiche ed altri inquinanti nelle componenti biotiche degli ecosistemi lotici

Microplastics and leaf litter decomposition dynamics: New insights from a lotic ecosystem (Northeastern Italy)

Microplastics represent one of the main environmental concerns of our time and their presence is well known in all freshwater ecosystems. However, there is still a lack of knowledge about the interference with some environmental dynamics, such as the leaf litter decomposition, which represents a key process in freshwater ecosystems. The work presented herein analyzed the leaf litter decomposition in a lotic ecosystem, in relation to water physicochemical parameters, macrobenthic invertebrate functional feeding guilds (FFG) and, as a novelty, the microplastics as additional factor. Physicochemical features were monitored every 15 days for one year. Phragmites australis decomposition rates were investigated during four seasons (summer, autumn, winter, and spring) using the leaf bag technique. Microplastic items were also collected within the leaf bags (used as retaining tool) and within macrobenthic invertebrate colonizers. Shredders were the most contaminated FFG in summer and autumn, while scrapers showed high microplastics levels in autumn and winter. Decomposition rates significantly differed among seasons (0.007 < k < 0.022) and water temperature was the main driver of the decomposition dynamics (relative importance = 70.3 %), positively affecting the decay rates, followed by pH (9.7 %), which showed a negative contribution. Microplastics showed a negative effect (3.1 %), with a relative importance similar and opposite to that observed for the shredders (3.9 %), which value was similar to those recorded for scarpers (2.7 %). This study represents a field investigation regarding the microplastic effects on the organic matter decomposition rates in freshwater environments carried out directly on field. Our results provide new insights about the microplastic interference on environmental dynamics and could represent a starting point for further studies

Microplastic patterns in riverine waters and leaf litter: Leaf bag technique to investigate the microplastic accumulation trends in lotic ecosystems

Microplastics (MPs) are one of the major ecological concerns of the last years and despite the increasing interest and the rise of many studies regarding freshwater habitats, many aspects about distribution patterns, transport pathways and impacts of MPs in those systems need to be investigated. The present study characterizes the temporal trends of MP concentrations in waters of a riverine stretch of the northeastern Italy, subject to flow rate variations and investigates the MP accumulations patterns in the leaf litter, simulated in situ via leaf bag technique. MP concentrations in the water were significantly and negatively correlated to the flow rate regimes, with higher concentrations observed during low discharge periods. MPs accumulation in leaf bags agreed with trends observed in the water and the presence of wastewater discharge points positively affects the levels of MP contaminations within the leaf bags. These findings seem to suggest that the maintenance of a hydrological regime at relatively high levels in the investigated system could allow to maintain the self-purifying riverine processes and the disposal of microplastics like any other polluting substance. The use of leaf bag technique for the purpose to investigate MP accumulation trends on field provided useful information, is easy to modulate in terms of time periods and allow to record the evolution of the MP patterns also in relation to high flow rate episodes. Our results suggest that the method can be employed in new a perspective, to improve the knowledge about one of the major threats of the Anthropocene.Peer reviewe

Ecological preferences of the south european nase lasca (Protochondrostoma genei, Bonaparte 1939) in the Chiarò di Cialla Creek (Northeast Italy): new insights and conservation perspectives

Freshwater ecosystems are among the most threatened environments, and inhabiting native fish fauna is very sensitive to anthropogenic impacts. Among the most vulnerable species, the south European nase (or lasca) Protochondrostoma genei is an endemic fish of the Poplain area, distributed also in the Adriatic basins and the southwestern districts of Slovenia (Kottelat & Freyhof, 2007; Carosi et al., 2022). It is included in the Annex II of the European Habitat Directive 92/43/EEC and is listed among the endangered species in the Red List of Italian Vertebrates (Rondinini et al., 2022). In the last years, populations showed fragmented condition and the distribution area significantly decreased, while the species became rare and sporadic in the marginal zones (Puzzi, 2022). This decline is mainly due to synergic effect of habitat degradation, loss and fragmentation (Carosi et al., 2022). Moreover, in the Isonzo River Basin the species is damaged by the allochthonous Chondrostoma nasus, which shares the same habitats. Recently, an abundant and well-structured P. genei population was observed in the Chiarò Creek (Northeast Italy, Isonzo River Basin), which was included in a Site of Community Importance (PSIC - IT3320041). Here, we analyzed ecological preferences for P. genei, as the information are still scarce in literature, despite recent projects for conservation purposes carried out in Slovenia (LIFE for LASCA). Fish samplings were performed from September 2021 to May 2022 and between March – May 2023. Main mesohabitats and main substrate types were recorded, while values of main chemico-physical parameters were measured. Fishes were sampled via electrofishing and the composition of the whole community was investigated, while the lasca specimens were measured to obtain size data and analyze population structure. Ecological preferences were investigated via Redundancy Analysis and highlighted that P. genei juveniles prefer pools and glides with moderate current velocity and require a discrete variability of refuge areas. Organic matter was also associated to the presence of juveniles, in relation to trophic requirements. Few specimens of C. nasus were collected, but they did not show a clear habitat preference in the investigated watercourse. The present work provides new information regarding P. genei, that could be helpful to prepare adequate management actions in the area and in other watercourses. As C. nasus was observed, an eradication project began in 2022, to perform population control and trying to limit damages to the lasca population