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A variety of organisms can colonize microplastic surfaces (or “plastisphere”) through biofouling processes. Heterotrophic bacteria tend to be the focus of plastisphere research, however, the presence of epiplastic microalgae within the biofilm has been repeatedly documented. Despite the importance of biofouling for microplastics in aquatic systems, data about this process are still scarce, especially for freshwater ecosystems. Here, our goal was to evaluate the biomass development of biofilms on plastic substrates and determine whether plastic surfaces exert a strong enough selection to drive species sorting, overcoming other niche defining factors driven by spatial patterns. We added microplastic pellets of high-density polyethylene (HDPE), polyethylene terephthalate (PET) and a mix of the two polymers in 15 mesocosms of 5 different locations of the Iberian Peninsula (totally 45 samples) and after one month we evaluated species composition and biomass of microalgae developed on plastic surfaces. Results show that all the different plastic substrates in all sites were colonized by microalgae with mean biomass of 3.05±0.40 mg cm-2, with PET having the highest value (3.63±0.83 mg cm-2). Microplastics supported the growth of many different species of microalgae (242 species), with some cosmopolite species that were able to colonize all different geographic regions and plastic surfaces. We found several species colonizing only one substrate, but with very low recurrence. Local species pools and different environmental conditions, mainly linked to biogeography, seem to prevail in driving community sorting on plastic surfaces.

Microplastics (MPs) constitute suitable substrates for the formation of biofilms. Since local conditions and environmental factors influence the community composition of biofilm, biogeography plays an important role in the composition of MP-colonizing communities. However, there is still controversy as to whether substrate-specific properties or environmental factors prevail in determining microalgal assemblages on plastic debris. In this study, we assessed periphyton growth on two different plastic polymers in freshwater mesocosms distributed across five locations covering a variety of bioclimatic regions in the Iberian Peninsula. In each location, pellets of high-density polyethylene, polyethylene terephthalate or a mix of the two polymers were deployed inside 2L transparent bottles suspended from surface rafts inside three different 1000L mesocosms. We measured water temperature, pH, conductivity, chlorophyll-a and nutrients in each mesocosm. After one month, MPs were collected and biomass and algal species composition were assessed. Microalgae colonized all the different plastic substrates in all sites with a mean abundance of 288±36 µg cm-2, with the highest biomass reported for PET (329±70 µg cm-2). Significant differences in the biomass development for the different polymers were highlighted for diatoms, which represent on average one of the taxa with higher biomass (29% of total biomass). Our results suggest that different plastic polymers may determine different colonizing conditions for specific taxa and may affect freshwater primary productivity.

Microplastics (MPs) can be colonized by a wide range of species (“plastisphere”). Even though plastisphere research mostly focused on heterotrophic bacteria, the presence of epiplastic microalgae has been repeatedly documented. However, studies investigating the colonization of MPs by microalgae are still limited, and mainly performed in marine environments. In this study, we assessed periphyton growth and diversity on two different plastic polymers (i.e., high-density polyethylene - HDPE, polyethylene terephthalate - PET) in freshwater mesocosms distributed across five locations in the Iberian Peninsula. Our results showed that colonization occurred in a range of diverse freshwater ecosystems, since we observed biofouling of the MP surfaces in all conditions, regardless of the sites and the plastic polymer type. The amount of biomass developed on substrates differed based on the polymer type, with higher biomass developed on PET substrate compared to HDPE. We observed a rich community of microalgae on both substrates (242 species), but we did not observe species-specificity in colonization of the different plastic polymers. Indeed, local species pool rather than polymeric composition seems to be the determinant factor defining community diversity.

Periphyton plays an important role in the nutrient cycling, energy flow and food web of aquatic ecosystems. Variation in the biomass, biodiversity and taxonomic structure of the periphytic algae community can provide information on changes in environmental conditions and can serve as a tool for ecological assessment. Here, we assessed periphyton growth and diversity on two different artificial substrates (i.e., high-density polyethylene - HDPE, polyethylene terephthalate - PET) in freshwater mesocosms distributed across five locations in the Iberian Peninsula. The aim was to evaluate differences in biomass and community composition of phytobenthos for artificial substrates with different incubation depth since HDPE substrates floated in water while PET, being denser than water, sank. Over the 45 samples analyzed, we found 242 different species distributed in 145 genera. The 33.5% belong to the phylum Bacillariophyta, followed by Chlorophyta (26.4%), and Cyanobacteria (8.3%). We found some cosmopolite species, which were recorded in almost all the samples, like Aphanocapsa incerta (Lemm.) Cron. and Kom. or Cocconeis placentula Ehr. Overall, 20 species occurred exclusively in HDPE samples, while 17 species only in PET samples. However, in all the cases these species had a low recurrence, being identified at most in four different samples. The amount of biomass developed on substrates differed based on the polymer type, with higher biomass on PET substrate compared to HDPE. Artificial substrates may host many different species of microalgae, but we did not observe a dissimilarity in community composition based on the different incubation depths. Instead, geographic and altitudinal gradient and nutrient concentration seem to be the most crucial factors in driven species sorting of epiplastic community.

Groundwater and surface water quality characterization consists in identifying the main hydrochemical features of a system by analysing experimental datasets. This requires proper statistical techniques to be carried out. Multivariate statistical analysis, in particular Factor Analysis (FA), has been widely applied for investigating water quality data. FA presents some limitations: the uncertainty of the data is not considered, and it aims at gathering together positive and negative correlated variables. In this study Positive Matrix Factorization (PMF) has been investigated as an alternative to FA (Paatero and Tapper, 1994). PMF is a multivariate analysis aimed at source identification and apportionment, specifically designed to cope with environmental data and to manage their uncertainty. PMF has been widely applied in studies concerning air pollution. A few studies demonstrated that PMF can be successfully applied to datasets concerning different environmental matrices (e.g. lake sediments and soil) to reach a more realistic representation of the sources affecting different systems. Here, the effectiveness of PMF as a tool to perform water characterization is investigated, by applying it to water quality data and comparing its results with those obtained with the more widely used FA. The study area is a part of the Oglio River basin after the outflow from Lake Iseo. It is a system characterized by strong relationships between groundwater and surface water bodies strongly impacted by agricultural landuse. This work is a result of the project “Lake, stream and groundwater modelling to manage water quantity and quality in the system of Lake Iseo – Oglio River” supported by Fondazione Cariplo (grant number 2014-1282) carried out between 2015 and 2018

Groundwater nitrate contamination represents a main environmental issue in Europe, despite the regulations implemented during the last 30 years. Therefore, to effectively address this persistent issue, the estimation of the time gap between the implementation of conservation measures and the observation of measurable improvements is fundamental. In the framework of INTEGRON project (CARIPLO Foundation #2015-0263), groundwater dating was performed and correlated to changes in groundwater quality in the Lombardy plain (northern Italy). The study area is currently one of the most impacted by nitrogen input in Europe, due to both agricultural and civil sources. In the northern sector of the plain nitrate concentrations often exceed the “concern” threshold of 25 mg/L, meanwhile the southern plain presents lower values. The overall aim is to estimate the time required for management actions to become effective, combining groundwater dating with different techniques and nitrate trend analysis.

We review the state of the art of limnological studies in Lake Iseo and provide updated data concerning long-term investigations (from 1993 to 2018) carried out on chemical and physical parameters (e.g., oxygen, phosphorus, silicon). Changes observed in Lake Iseo were compared with those reported in other Deep South alpine Lakes (DSLs) to highlight analogies and differences of long-term chemical, physical, and biological patterns. Until the 1960s, Lake Iseo and other DSLs were oligotrophic. The increase of anthropogenic pressure and global warming has led to a progressive and unrecovered process of eutrophication. Moreover, the decrease in frequency of full mixing episodes has induced a state of temporary meromixis. Other changes have been identified over the last two decades, especially concerning the phytoplankton and zooplankton communities, and new emerging chemical pollutants were detected. Given the important ecological and socioeconomic role of Lake Iseo, long-term investigations are of paramount importance to understand the response of the lake ecosystem to climatic and anthropogenic stressors. These two factors can also act coupled with new combined and synergic effects. ny.

Lake deposits provide ideal archives to study the past catchment dynamics and the related response of lake ecosystems. In particular, sediment records deposited over long time periods can provide information on lake development stages preceding the moment of the most relevant human disturbance, and can help disentangling and quantifying the lake ecosystem responses to natural variability and human perturbation, such as climatic and hydrological variation, eutrophication and chemical contamination. Subfossil Cladocera records allow tracking long-term changes in both bottom-up drivers and top-down regulators and they particularly respond to alterations in nutrients, temperature and water level. The aim of this work was to investigated a short sediment core from a deep subalpine lake (Lake Iseo, northern Italy) aiming at reconstructing the influence of human activities and climate variability on the lake ecosystem. We compared the sediment records with historical information on major hydrological events during the last century, and with climate-related limnological data. As already observed in other subalpine lakes, the sediment records of Lake Iseo suggest that catchment related processes are able to decisively affect the food web dynamics and the lake functionalities. In particular, we observed that a series of flood events in the period between the 1970s and 1980s resulted in a decrease in the Cladocera total abundance and a prevalence of the littoral species over the pelagic one. The decline of the pelagic species has been attributed to the transport of inorganic material from the catchment area to the lake.

Catchment area changes (e.g. river hydrology, nutrient loads, land use), driven by climatic variation or anthropic activities, can have a strong impact on lake ecosystems. In particular extreme flood events can bring a lot of material in lake basin affecting water transparency and consequently impacting on the biocenosis. In previous studies has been verified that this phenomenon is amplified in lakes with a large ratio between drainage basin and lake area. Lake deposits provide ideal archives to study the past catchment dynamics and the answer of lake ecosystems. In particular, subfossil Cladocera remains are a valuable biological proxy, able to provide information on lake responses to hydrology- and climate-related environmental perturbations. Lithological analyses combined with subfossil remains can reveal responses of lake ecosystems to changes in the catchment area. The aim of this work is a paleolimnological reconstruction of human, climate and hydrological impacts on a deep subalpine lake (Lake Iseo, northern Italy) during the XX century. We study the lithological parameters and Cladocera and diatoms subfossil remains record in an 80 cm long sediment core spanning from the early 1920s to 2014. We compare the sediment records with historical information on major hydrological events during the last century, and with climate-related limnological data. As already observed in other lakes, the sediment records of Lake Iseo suggest that catchment related processes are able to decisively affect the food web dynamics and the lake functionalities. In particular, we observed that a series of flood events in the period between the ‘70s and ‘80s resulted in a decrease in the Cladocera total abundance and a prevalence of the littoral species over the pelagic one. The decline of the pelagic species has been attributed to the transport of inorganic material from the catchment area to the lake.

Daphnia is a keystone organism in pelagic food webs, acting as a food resource for fish and predatory zooplankton and regulating phytoplankton through grazing. Its population dynamics follows a regular seasonal pattern, where a spring density peak is followed by a population summer decline. This phenomenon (midsummer decline, MSD) shows high inter-annual variation and it has been attributed to different causes; however, the underlying mechanisms remain poorly understood. Our study aims to disentangle the pathways that lead to Daphnia MSDs in two deep peri-alpine lakes, Lugano and Iseo. We hypothesized that: (I) winter air temperature controls MSDs by influencing mixing depth during turnovers and nutrients availability; (II) vernal air temperature directly influences MSD by accelerating the timing of spring population peak; (II) summer temperature indirectly influences MSDs by increasing fish predation. We tested the hypotheses using Structural Equation Modelling on long-term datasets for the two lakes (29 years for Lake Lugano and 19 years for Lake Iseo). Winter air temperature, affecting vertical mixing depth and consequently epilimnetic phosphorus concentration, had the major influence on Daphnia phenology during spring and summer, but the effects were stronger in Lake Lugano, where the lower lake-water P concentrations might have been more limiting.

Microgreens have been recently introduced as a new category of vegetables, with unexploited potential as functional foods. Due to containerized production, they can be commercialized while growing on the medium, ready for being harvested before use. The chlorophyll content of vegetables is important for both health benefits and visual appearance of the produce. This paper aims to evaluate the feasibility of using simple tools to monitor chlorophyll content in microgreens of two different species, broccoli raab (Brassica rapa L., Broccoletto group) and radish (Raphanus sativus L.), in varying stages of cold storage in their growing vessel. Image acquisition with a CCD camera, followed by image analysis using preset algorithms of an open source software (ImageJ) was the approach used. Image color analysis (median values of L∗, a∗, and b∗indices) and textural parameters obtained from the gray-level co-occurrence matrix (GLCM) allowed to obtain regression models for chlorophyll content with satisfactory fitting parameters (adjusted R2 was 0.765 and 0.843 for broccoli raab and radish, respectively). These results point out the possibility to set up low-cost, real time, non-destructive monitoring systems for microgreens quality during their growing as well as during storage.