High-mountain lakes are remote freshwater ecosystems with limited accessibility. These lakes host simplified biotic communities, primarily benthic macroinvertebrates in the littoral zone, which serve as bioindicators of environmental pressures. To better understand the specific processes within these ecosystems, it is recommended to evaluate them on a fine spatial scale. A two-year monitoring study was conducted in July 2022 and July 2023 at Nero Lake (2020 m a.s.l., Cesana Torinese, Northwest Italy). The monitoring of the lake evaluated three main aspects: the composition of littoral benthic macroinvertebrate communities, the differences in these assemblages between the two years, and site-specific factors influencing the macroinvertebrate community. Five sites along the lakeshore were selected for measuring physicochemical water parameters and sampling macroinvertebrates. Data collected were analyzed to compare trends across years and within specific sites. The results revealed that Nero Lake exhibited consistent macrobenthic communities across the two years studied, but significant differences were observed in its microhabitats. This suggests that substrate type and physicochemical water parameters influence community composition. Chironomidae larvae and Mollusca were the dominant species, showing distinct associations with different substrates and environmental factors between years. The variability observed in microhabitats indicates that even small-scale environmental fluctuations can have significant impacts on community structure, stressing the need for continuous and precise environmental monitoring. The study’s findings contribute to our understanding of the relationships between benthic macroinvertebrates and their environments, highlighting the necessity of detailed, small-scale assessments to comprehend ecosystem dynamics and develop effective conservation strategies.

High-mountain lakes in the Alps, despite their remote locations, are vulnerable to chemical pollution. This presentation examines these lakes as repositories for Persistent Organic Pollutants (POPs) and Contaminants of Emerging Concern (CECs), highlighting their sources and impacts on both the environment and human health. Fourteen studies have explored POPs in these lakes, focusing on substances such as polychlorinated biphenyls, DDT, and its metabolites, polybrominated diphenyl ethers, and polycyclic aromatic hydrocarbons. Most research on POPs in high-altitude lakes is concentrated in the Italian Alps (63%), with further studies conducted in Switzerland (22%), Austria (12%), and France (3%). The primary focus is on sediments (65%), followed by fish (33%) and water (2%). In terms of CECs, six studies have investigated the presence of musks, perfluorinated compounds, and microplastics. These studies are mainly conducted in Switzerland (42%), France (33%), and Italy (25%), with fish samples (46%) being the primary focus, followed by sediment (17%) and water (17%). Other compartments like zooplankton, frogs/tadpoles, and snow are less frequently studied. This presentation also covers the pathways through which pollutants reach these remote lakes, including atmospheric transport, glacial meltwater, and human activities. Protecting these pristine environments requires continuous research, vigilant monitoring, and dedicated conservation initiatives.

Temporary Ponds (TP) represent critically endangered habitats, declining in number and hydroperiod length throughout the whole of their Italian range. Knowledge of diatom community structure, ecological preferences and distribution patterns help us to determine the conservation status and the influences of environmental variables on TP. Here, we link diatom community structures, environmental variables and geographical constraints to quantify the changing influence of hydroperiod length on diatom community structure of 6 ponds across an altitudinal gradient, from the Tyrrhenian coast to the Italian Apennines. Over twelve months of samplings, we found that alpine ponds hydroperiod is limited to five months (June – October). Based on a comprehensive data set of 72 samples from 6 TP, we showed that the factors best explaining benthic diatom community structures were electrical conductivity, pH and altitude. The results revealed how “motile” diatoms showed the best adaptations to the typical droughts of TPs. Moreover, low-altitude diatoms live in assemblages largely structured by interspecific competitive interactions, while alpine ponds are mainly structured by aggregation patterns. Of over 150 diatom species identified, approximately 15% are also included in the Red List of endangered species. Overall, alpine ponds show less species richness than Mediterranean ponds. Short hydroperiods can influence diatom communities. We hypothesize that the restricted dry phase typical of Alpine ponds didn’t allow the community stabilization, favoring the settlement of first-stages pioneers species. Moreover, using diatom species ecological sensitivity values and a set of environmental factors combined in the EPI-D diatomic index, average good water quality was described for the ponds, highlighting better values for Mediterranean ponds.

This study contributes to increase awareness on conservation of this neglected habitats and will aim to inform future environmental legislation by understanding the hidden ecological importance of ponds and diatoms suitability for temporary freshwater biomonitoring.

Lakes in polar regions are significantly present and dot the landscape, especially in coastal areas. These lakes not only cover vast areas but also represent unique ecosystems teeming with life. Particularly, the microbial communities within Antarctic lakes are of notable interest, as they play a crucial role in mobilizing nutrients for both autotrophic and heterotrophic life forms. The MicroPolArS project (Microbial Response to Human Pollutants in Polar Lakes) enabled the study of microbial communities in the water and sediment of 12 polar lakes (5 Arctic and 7 Antarctic). Water and sediment samples were collected in the field as aseptically as possible and pre-treated in the Italian Dirigibile Italia station (Arctic) and the Spanish bases Gabrielle de Castilla and Juan Carlos I (Antarctica). Once in Italian laboratories, DNA was extracted from the samples using specific kits and subjected to 16S rRNA gene barcoding sequencing. The results were analyzed using our pipeline to identify the ASVs (amplicon sequencing variants) in each sample. The analysis highlighted a significant difference between the microbial communities of the sediments and those associated with the waters. Additionally, lakes associated with glaciers showed considerably lower diversity (Shannon H’ index average 2.6) compared to coastal lakes, which are frequented by migratory birds (Shannon H’ index average 5.1). Notably, differences between Arctic and Antarctic lakes were substantial, even among lakes with the same origin and physicochemical characteristics, indicating divergent microbial communities in these extreme environments. Even if more analyses are needed this study underscores the unique and diverse microbial ecosystems in polar lakes, revealing significant differences between sediment and water communities, as well as between Arctic and Antarctic lakes, emphasizing the complexity and variability of microbial life in these extreme environments.

The rapid response of phytoplankton to environmental changes makes this community among the most important ecological indicators in the study of marine ecosystems. This is particularly true for polar regions, where the high dynamism and strong gradients produce a great community variation, whose scale of investigation often depends on logistic constrains rather than ecological and biological processes. The Ross Sea (RS, Antarctica) is the most productive region of the Southern Ocean, where the phytoplankton community dynamics have been so far described mainly in relation to physical-chemical properties of the water column, and dominated by diatoms and haptophytes showing distinct niches. In recent years many studies have documented changes in the phytoplankton community dynamics in the RS that contrast the classical Antarctic paradigm and open new questions about the importance of considering the trade-off between autoecological and synecological processes in the ecology of such a complex system. Since the growing attention in trait-based approach in the study of marine systems, we have considered the phytoplankton size classes (due to their role in shaping food web characteristics) and the chemotaxonomical functional groups (because of their great variability in relation to environmental constrains) for investigate on the RS blooms dynamic and the potential linkage phyto-microzooplankton in two RS polynya areas during the Austral summer 2017. Our results emphasize the existence of distinct ecological patterns between different RS subsectors, suggesting that the use of plankton functional traits represents a valid and still poorly used monitoring tool in studying the response of polar systems to climate change.