This speech serves as an introductory contribution to the discussions on the "Effects of Climate Change on Ecosystems" session. Ecosystems are communities of living things, including plants, animals, and microorganisms, interacting with each other and the physical world. People rely on ecosystems for many benefits, such as food, water, clean air, building materials, and recreation. Ecosystems can vary in size, from large ones (areas surrounding a national park) to as small as a single fallen tree. They can also overlap with one another or be part of larger ecosystems. These connections between ecosystems make them dependent on one another, and not dependent on the organisms within them. Climate change affects ecosystems in many ways. Climate controls how plants grow, how animals behave, which organisms thrive, and how they interact with the physical environment. The IPCC warns that if current warming trends continue, global temperatures could double by 2030-2052, causing devastating effects on ecosystems worldwide. The ocean, which absorbs over 80% of global warming, is particularly affected. Elevated sea-surface temperatures are damaging coral reefs, leading to bleaching and extinction. Ocean acidification, caused by higher CO2 levels, further threatens corals and shelled sea creatures. Sea levels are rising due to ocean water warming and the melting of land-based glaciers. Over the last century, the sea level has increased by an average of 20 centimeters. All regions at the global level are experiencing the impacts of climate change, but impacts vary by area and ecosystem. People are taking many actions to help ecosystems adapt to climate change impacts or minimize the effects. For example, environmental agencies that manage the nations' natural resources are now considering climate change in policies and planning. At the local level, many groups are preserving habitats and restoring ecosystems that have been damaged or disturbed in the past.

Agricultural food security is threatened by climate change impacts, which can distress crop growth and favor the spread of infectious diseases. We examinethe synergism of two potential causes of future yield failure in peach production: the effects of global climate change on fruit tree blooming and on the spread of fungal diseases.
The ‘disease triangle’, well-known concept in plant pathology that represents the interplay between the environment, plant hosts, and pathogens, was evaluated for brown rot in peach orchards in light of climate change. Coupling a climate-driven mechanistic phenological and epidemiological model across the French continental territory, we provided projections of yield losses for four peach cultivars (early, mid-early, mid-late, and late) in the XXI century under different climate change scenarios. We considered as adaptation strategy the possibility of shifting peach production sites to new suitable areas.
Global warming is expected to impair fruit phenology with blooming failure events in the south-western part of the country that comprise the 31% of the French territory at the end of the XXI century. This will be less extreme under the more moderate greenhouse gas (GHG) emission scenario, even though sporadic blooming failures will still occur that will involve less than the 10% of the French territory. In contrast, future warmer and drier conditions will decrease brown rot-induced yield loss in the historicallocations devoted to peach cultivation. Thanks to the considered adaptation strategy, the peach national yield could still be fulfilled even under the most extreme GHG emission scenario. Comprehensive mathematical frameworks, that concomitantly consider the climatic effects on the plant hosts and on their pathogens, are required to provide reliable future predictions of crop yields and to inform control and adaptation strategies to guarantee food security under global warming.

Oceans are critical for sustaining life on Earth, acting as carbon sinks, regulating climate, and providing essential ecosystem services for human wellbeing. Net Primary Production (NPP), defined as the rate at which phytoplankton convert inorganic carbon into organic matter via photosynthesis, represents the primary process sustaining the flow of energy into ecosystems. Consequently, from a theoretical point of view, NPP may also represent the most important driver influencing species richness and abundance. This study represents a proof of concept of the intricate relationship between NPP and biodiversity in marine ecosystems on a global scale, utilizing data from satellite observations and in-situ measurements. Results indicate a strong linear correlation between NPP and biodiversity, suggesting that higher productivity supports greater species richness and ecosystem resilience. Moreover, our findings highlight that diverse marine ecosystems tend to be more productive due to factors such as complementarity and functional redundancy among species. However, this relationship is complex, with some highly diverse ecosystems potentially experiencing reduced productivity due to competition for resources. Current trends in global environmental changes, including global warming and eutrophication, are likely to alter this balance. Warming sea temperatures, changes in ocean stratification and nutrient availability can impact NPP, which in turn affects marine biodiversity. This research underscores the importance of understanding NPP-biodiversity dynamics for developing effective conservation strategies. While the prevailing trend in marine ecosystems is a reduction in NPP in response to ongoing climate change, local trends may vary due to the influence of other environmental variables, resulting in a higher level of uncertainty. Using easily accessible satellite data, such as NPP, to inform biodiversity expectations could be a valuable tool for planning and managing conservation policies. Our study contributes to this understanding by integrating comprehensive data and emphasizing the need for adaptive approaches in marine conservation amidst changing global conditions.

Biological invasions are one of the major drivers of biodiversity loss. Efficient conservation efforts require knowing where negative impacts on biodiversity are likely to occur in the future, taking climate change into account.

The environmental impact classification for alien taxa (EICAT) is a well-known standardized system adopted by IUCN to score and compare impacts of alien species to native biodiversity and can be potentially used to predict invasion threats to biodiversity in Europe. We selected 100 terrestrial alien plant species known for their high potential for impacts. For each of them, we (i) assessed the EICAT impact score, (ii) fitted ensemble species distribution models and (iii) matched impact scores and geographical distributions across alien plant species to map the risk of biodiversity loss due to plant invasion in Europe, in the present and in 2050 under different climate change scenarios.

Preliminary results showed that several species with major impacts, inducing local extinctions of native species, have the potential to spread widely throughout Europe. Coastal, mountain and northern regions showed higher potential increase in the intensity of impacts in future climatic scenarios. Competition with native species in invaded communities, chemical and structural impacts on ecosystems were the most common mechanisms though which these alien plants are likely to affect biodiversity in Europe.

This study employs a modelling approach to assess the impact of climate change on four key species—Quercus cerris, Fraxinus angustifolia subsp. oxycarpa, Phillyrea latifolia, and Pistacia lentiscus—within a Mediterranean forest ecosystem. Field measurements, obtained using an infrared gas exchange analyser, inform the calibration and validation of a modified Farquhar and Caemmerer biochemical model of photosynthesis. This species-specific model simulates instantaneous net assimilation (μmolCO₂/m²s), stomatal conductance (mmolH₂O/m²s), and transpiration rates (mmolH₂O/m²s). To account for each species’ unique water-use efficiency, we incorporate marginal carbon cost theory in transpiration estimation.

By integrating model results over time, we obtain gross and net primary productivity, and transpiration values for each species under current climate conditions (2022) and future climate change scenarios (Shared Socioeconomic Pathways (SSP) 2.6 and 8.5). Key findings include:

1. P. latifolia and F. oxycarpa exhibit reduced annual net primary productivity under the SSP 8.5 scenario (179 and 624 gC/m²y) compared to 2022 levels (227 and 674 gC/m²y).
2. Conversely, P. lentiscus and Q. cerris demonstrate increased annual primary productivity in the SSP 8.5 scenario (872 and 425 gC/m²y vs. 828 and 392 gC/m²y of 2022).
3. Annual transpiration values are expected to rise for Q. cerris and P. lentiscus (from 392 and 484 gH₂O/m²y in 2022 to 444 and 532 gH₂O/m²y in SSP-8.5), while decreasing significantly for F. oxycarpa (from 674 gH₂O/m²y in 2022 to 227 gH₂O/m²y in SSP-8.5) and marginally for P. latifolia (from 227 gH₂O/m²y in 2022 to 206 gH₂O/m²y in SSP-8.5).

The model provides insights into how different species respond to climate change, which can be useful in guiding conservation and management strategies in ecological restoration projects.

Freshwater ecosystems play a crucial role in providing globally relevant ecosystem services. Yet, freshwater communities worldwide have experienced substantial declines due to human-driven changes, with non-native fishes and global warming identified as major threats. Although it is known that most fish are ectotherms, thus metabolically influenced by temperature, the effect of warming on fish impact has often been overlooked.

Among freshwater fishes, the eurythermal Micropterus salmoides is one of the most widely introduced and invasive species. Its predatory pressure has altered species composition and size structure of invaded communities, with M. salmoides often becoming the dominant predator. Although the species has been increasingly studied over the last few decades, the role of temperature in its predatory impact has only been marginally considered.

In this manipulative laboratory study, Functional Responses (FRs), describing the feeding rate as a function of prey density for M. salmoides and trophically analogous fish species (Esox cisalpinus and Perca fluviatilis), provided valuable insights into the effect of temperature (+3-6 °C increases) on predatory response and outcomes of competition between these predators. An increase in functional response (+418%) on prey populations with rising temperatures was recorded for the invasive species. Conversely, decreases in functional response and increases in mortality were recorded for the native ones. The differences in FRs were related to changing prey handling (which includes capture, consumption, and digestion of prey and defines the magnitude of the FR curve) with temperature.

The study highlights that the impact of M. salmoides on prey populations is expected to increase with warming, while native predators may experience a reduction in their competitive capacity, with implications for species coexistence and food web dynamics. Investigating the effects of biological invasions and climate change separately is therefore not sufficient for accurately measuring ongoing changes and appropriately managing ecosystems.

Seagrasses are essential to marine ecosystems, where they often play the role of foundation species and provide key ecosystem services, from habitat provision and coastal protection to water purification and carbon sequestration. We collated distribution data for >90% of Mediterranean seagrass species to analyze their vulnerability to climate change using species distribution modeling and climate-niche factor analysis. Our results show that seagrasses generally exhibit narrow ecological tolerances to variations in the environmental variables associated with their current distribution, indicating high sensitivity to climate change. Our study highlights the increasing vulnerability of seagrasses under progressively more severe climate change scenarios and, in particular, identifies significant risks under SSP 8.5. We also find that Posidoniaceae consistently show higher levels of vulnerability than Cymodoceaceae, and that the Adriatic Sea is a regional hotspot of vulnerability compared to other Mediterranean sub-basins. Our study thus highlights the need for targeted mitigation strategies to protect seagrass habitats from the impacts of climate change, and suggests ways to prioritize interventions based on the differential vulnerability projected for different taxonomic groups and/or geographic regions.

Coastal sand dunes are ecologically and economically important habitats but are threatened by multiple factors including climate changes. Climate scenarios predict the intensity and frequency of precipitations will decrease in coastal Mediterranean areas by the end of the century. Water shortage associated with reduced precipitations is a major factor limiting seedling survival in dunes. A greater precipitation reduction is expected in spring, a period favorable for dune plant recruitment. Depositions of Posidonia oceanica wrack can be also present along beaches and embryo dunes. This material can provide essential nutrients to dune plants, but whether it can affect the ability of seedlings to cope with abiotic stressors like water shortage is still largely unknown. Here, the individual and combined effects of precipitation amount (current vs. predicted reduced according to SSP2-4.5 stabilization scenario) and wrack deposition (no wrack vs.wrack alone vs. wrack plus sand) on seedling establishment and growth of three dune species, Cakile maritima, Thinopyrum junceum, and Calamagrostis arenaria, were investigated in mesocosm. Wrack water holding capacity and leachate chemical/physical properties were also evaluated. Neither precipitation nor wrack affected seed germination and seedling emergence success for all investigated species. Reduced precipitation decreased root development while wrack promoted seedling aboveground elongation, regardless of its composition. Reduced precipitation also reduced biomass production in T. junceum and C. arenaria but only in the absence of wrack. Wrack retained water up to five-fold its weight and increase water pH, conductivity, and nutrient content. Our findings indicate that expected reduced precipitations could make dune plant seedlings more vulnerable to additional stressors. But wrack could mitigate reduced precipitation effects in T. junceum and C. arenaria by retaining most available water. Thus, maintaining P. oceanicawrack on beaches could be a valuable, eco-sustainable strategy for supporting the resilience of dunes under ongoing climate change.

Dissolved oxygen in water represents an essential substrate for most marine ecosystems. Its concentration is steadily decreasing in response to global warming. Alhough short-term impacts are well understood, the spatiotemporal paucity of instrumental records, coupled with numerical simulations with conflicting predictions about the future of oxygen deficient zones (ODZs) in the tropical Pacific, makes it difficult to make long-term predictions about the future of oxygen in the oceans and the resulting impact on marine ecosystems.

An alternative and complementary approach is given by the study of global warming events in the history of our planet that have left a tangible and measurable trace in the geological record. The use of geochemical and morphometric analyses on fossil organisms can provide important information on the long-term response of ocean habitability to temperature rise. We show here new evidence in favor of tropical subsurface oxygenation during the Paleocene-Eocene Thermal Maximum (PETM), a rapid global warming event that serves as a “geologic analogue” to ongoing warming.

The isotopes of organic nitrogen on fossil planktonic foraminifera shells indicate that the tropical Pacific ODZ contracted during the PETM, implying an increase in oxygen in the vicinity. The plication of the metabolic theory of aquatic ectotherms in the fossil record, shows that the increase in size of tropical planktonic foraminifera, despite warming, implies that oxygen availability increased in the tropical Pacific.

These changes are consistent with biogeochemical models for the SSP5-8.5 scenario for 2300, in which a decline in biological productivity and subsequent respiration rates allow tropical oxygen to increase, even as global ocean oxygen decreases. The upping tropical oxygen may have alleviated the physiological stress on planktonic organisms in areas of higher biodiversity, helping to avoid a mass extinction of planktonic organisms during the PETM, despite the largest benthic extinction in the Cenozoic.

Crustose coralline algae (CCA) are among the major calcifying organisms in the Mediterranean Sea and are important foundation taxa in the photic zone. They enhance the structural complexity of marine ecosystems, promoting settlement and metamorphosis of various invertebrates. Due to multiple local factors and climate change effects, coralligenous reefs are in decline. Investigations on CCA, the foundation species, are therefore necessary to know their adaptability to different conditions and thus to evaluate the possibility of possible restoration actions based on CCA transplantation. To this end, a manipulative field experiment was conducted in Costa Paradiso (North Sardinia, Italy) where CCA recruited at 35 m of depth on artificial substrates (terracotta and ceramics 10x10 cm tiles) with varying initial coverage (high and low): to disentangle the effects of irradiance from those of the temperature, three treatments were used by fixing the tiles at 1) 15 m of depth where they were placed in a natural cavity so that the algae could experience the 35 m light irradiance but water temperature above the thermocline (LLHT), at 2) 15 m of depth outside the cavity (HLHT), and at 3) the same origin depth, 35 m, where irradiance was low and temperature below the thermocline (LLLT). The recruits exhibited greater growth when exposed to higher temperature compared to those in combined low light and low temperature conditions. A posteriori, molecular and morphological analyses were conducted to identify the CCA species which allowed estimating the species-specific growth rate at the studied conditions.

Managing marine aquatic resources is a complex challenge due to the intricated processes unfolding at sea. This challenge is amplified in the Mediterranean Sea, where pronounced seascape, climatic, and social variability critically affect the biodiversity of the basin across sub-regions. The traditional approach to fisheries management in this area has long relied on stock assessment with classical stock-recruitment models to reconstruct historical population dynamics and predict their response to different effort regulation measures. However, these methods lack robust predictive power due to their limited ability to incorporate changing environmental conditions and anthropogenic pressure. Our work proposes a spatially explicit metapopulation model of the European hake (Merluccius merluccius) within the area of the Adriatic and Ionian Seas. The model integrates the effect of environmental variables on life-history traits and larval connectivity. This approach, therefore, allows us to predict the response of the hake stock to different scenarios of climate change (RCPs) and fishing pressure, generating a realistic representation of the stock dynamics in the medium to long term and predicting the potential future spatial distribution of the stock. This tool enables the mapping of different performance indicators in space and time, informing the development of area- and effort-based management strategies that optimize resource conservation while identifying areas particularly sensitive to management interventions. This modelling framework provides a flexible and valuable tool for designing effective marine protected area networks and facilitating sustainable fisheries management practices.

In the Mediterranean Sea the temperature increase has accelerated over recent years, affecting at different levels key species like the endemic seagrass Posidonia oceanica. Recently, in warm-edged locations of Mediterranean basin, P. oceanica bleaching (i.e. discoloration of leaves still attached to the shoots) has been observed in late summer, but the factors that trigger the phenomenon remain unknown. This study aimed at i) estimating the spatio-temporal variability of P. oceanica leaf condition in Konnos Bay, Cyprus (mensurative experiment) and ii) investigating the role of light irradiation and temperature on leaf bleaching by a reciprocal transplant of plant cuttings from different depths under a light gradient obtained by using shading nets (manipulative experiment). To pursue our goals, morphological (i.e. leaf area, leaf necrosis, leaf bleaching) and eco-physiological (i.e. chlorophyll, carotenoids, anthocyanins) responses were considered. The hypothesis supported by the mensurative experiment is that interactive effects of irradiance and temperature (both continuously recorded by loggers) are responsible for the extent of bleaching and, as consequence, during summertime, shallow untouched P. oceanica plants are expected to bleach before the deep ones due to the exposure to higher temperature and irradiance conditions. The manipulative experiment could shed light on the effects of the variability of conditions influencing the seagrass leaf status of transplanted plants. More specifically, the occurrence of bleaching on deep cuttings transplanted at shallow depth without shading net, would support the hypothesis of the join temperature and light sudden variation in bleaching induction. Both approaches will allow to identify a potential modulation of light harvesting pigments found in the shoots at different depths as a plant defense strategy. Analyses are ongoing and both experiments will last until August 2024.

Mountain regions are recognised as climate change hotspots. Increasing evidence from observations and model studies indicates that warming rates depend on elevation and often intensify with elevation, causing high-altitude environments to experience more rapid temperature changes than lower elevations. This phenomenon, known as Elevation-Dependent Warming, has been extensively studied due to its potential to accelerate transformations in mountain ecosystems, cryospheric systems, hydrological regimes, and biodiversity. However, fewer studies have examined the elevation-dependent changes of other climate variables, such as precipitation and its extremes (Elevation-Dependent Precipitation Change), that are as important as the temperature for high-altitude environments and downstream. Precipitation is crucial for mountain hydrological resources as its study in the context of climate change. Elevation and complex terrain significantly influence precipitation formation, contributing to the increase of extreme precipitation events. In this contribution, we present an analysis of the changes in mean precipitation and its extremes in ERA5 global reanalysis data in key mountain areas of the globe, along with their elevational dependence, from 1951 to 2020. The areas include the Tibetan Plateau, the US Rocky Mountains, the Greater Alpine Region, and the Andes, as representative of different latitudes and climatic influences. Our analysis reveals common patterns of elevation-dependent change in precipitation and its extremes in most of the mountainous areas, which emerge beyond their geographical differences. A positive elevational gradient of extreme precipitation trends is found in the Tibetan Plateau, the Greater Alpine Region, and the subtropical Andes, highlighting a wetting effect (positive trends) at very high elevations. In contrast, the Rocky Mountains exhibit a negative elevational gradient, with a drying effect (negative trends) increasing with the elevation. Mean precipitation, heavy (≥10 mm/day) precipitation and the length of consecutive wet days show a consistent elevation-dependent stratification within each of the study areas, suggesting possible common driving mechanisms.

Climate change affects natural and semi-natural ecosystems worldwide, with mountains experiencing even more drastic impacts due to elevation-dependent warming. High-elevation grasslands and alpine tundra act as regulators of the hydrological cycle, stabilise slopes and have a paramount role in nitrogen and carbon cycling. Owing to the very short snow-free season and the consequent adaptation of alpine plant to fast growth, alpine ecosystems mainly act as carbon sinks, with primary production usually exceeding ecosystems respiration. Combining timeseries of field (CO₂ fluxes and environmental variables; 3,590 single measurements - 5 sites), weather (daily precipitation and temperature), vegetation (PFT classification - 653 images) and remotely sensed data (CLr, NDSI, DEM) in the Nivolet area (Gran Paradiso NP, Italy), we investigated the environmental and climate controls on ecosystem respiration and primary production using structural equation modelling. We found GDD₀ (growing degree days since snowmelt) exerting a strong control on both respiration and production. The effect of GDD₀ on production is both direct, possibly reflecting the importance of cumulated heat on vegetation height, and mediated by the seasonal trend in greening (proxied by CLr). While greening had no effect on respiration, GDD₀ had a direct effect, supporting the view that ecosystem respiration was mainly microbial-driven and temperature-related. Summer cumulative precipitation proved to promote both respiration and production, at least until the phenological peak. Surprisingly, winter cumulative precipitation had no effect on production, and a negative effect on soil respiration, suggesting a direct effect on the cycling of organic matter rather than a contribution to the spring/summer water balance. Other variables (i.e., radiation, air temperature, soil moisture, PFT, topography) all supported our a-priori expectations or had no significant effect. Our results contribute to identify the causal relationships between climate and carbon cycling, allowing for a deeper understanding of the effects of climate changes on alpine ecosystems.

Spontaneous afforestation of formerly man-used land has increasingly been considered as a Nature-Based Solution to mitigate climate change. Besides obvious C sink above ground, afforestation leads to low soil pH, high C:N ratios and changes in litter and soil organic matter (SOM) quality with beneficial implications for soil carbon sequestration. However, less is known about the effects on soil microbial communities, which may play a crucial role as a controlling factor for nutrient cycling, SOM stabilization and soil fertility. The aim of this study, within the framework of Task 4.2.1 of Spoke 4 of the National Biodiversity Future Centre (NBFC), is to investigate the dynamics of carbon stocks and soil microbial diversity following afforestation in Julian Pre-Alps (Taipana, UD) using a space-for-time approach. Orthophotos were used to identify and date the successional stages spanning 70 years from grassland to forest.Organic C pools including soil, living trees, standing and lying dead wood and litter, as well as main physical-chemical properties including fine C molecular composition by 13C-CPMAS NMR, were measured, and fungi and bacteria community diversity was assessed by soil DNA metabarcoding.Aboveground C stock increased from 8.42 ± 0.91 tC ha^-1 in grassland, to 158.98 ± 23.85 tC ha^-1 in the oldest stands. Soil C stock, after initially decreasing from 63.62 ± 15.4 tC ha^-1 in grasslands to 47.74 ± 3.34 tC ha^-1 in shrubby sites, significantly increased along the successional process, reaching 78.44 ± 19.42 tC ha^-1 in mature forest. Microbial α-diversity substantially differed between bacterial and fungal communities, with the formers progressively declining while fungi showed a bell-shaped response peaking at intermediate successional stage (34 years).These findings open interesting perspectives for the management of rewilding dynamics suggesting alternative scenarios targeting either climate change mitigation and/or ecosystem resilience, with the latter strictly associated to the functional redundancy of microbial diversity.

Cryoconite holes are small depressions (from millimeters to tens of centimeters) in the ice surface of glaciers, filled with water and sediment at the hole base. The term ‘cryoconite’ refers to the granular sediment comprising mineral (e.g. soil or dust) and biological material. The cryoconite holes can cover a large portion of a glacier and are now recognized as an important microbial habitat and a major element of supraglacial ecosystems. Their autotrophic component plays an essential role in maintaining the whole cryoconite food chain, decreasing the albedo of glaciers, and representing a source of organisms for the emergent new ice-free area. However, the study of photoautotroph community in cryoconite ecosystems is complex, because the presence of dark sediment and the difficult cultivation of organisms make both molecular analyses and standard microscopic approaches complex. Here, we aim to gain insights into the diversity and composition of microalgae and Cyanobacteria in cryoconite holes from different glacial locations. Based on an innovative methodology, we provide a highly comprehensive description of the phenotypic characteristics, abundance, and structure of the autotrophic community in these extreme environments. The study poses the basis for the taxonomy of photoautotrophs in glacial habitats and their ecological role in cryoconite systems.

Alpine high-mountain lakes, often considered scenic marvels, play critical roles as indicators of global environmental change, repositories of geological history, and vital freshwater sources. Despite their pristine and remote locations, these lakes face significant threats that modify their ecological equilibrium. Climate change, primarily through glacier retreats, shifts in water temperatures, and heightened UV radiation levels, poses a substantial risk. Furthermore, pollutants transported over long distances, the introduction of invasive species, rising water demand from Alpine storage power stations, and expanding tourism and recreational activities further heighten vulnerability, exacerbating habitat disturbance and environmental degradation.

This study underscores the crucial importance of Alpine high-mountain lakes, emphasizing the urgent need to address both established and emerging threats. It outlines future research priorities focused on developing comprehensive monitoring programs and proactive conservation measures, highlighting the necessity of understanding the ecological health of these ecosystems, evaluating environmental impacts, and formulating effective strategies. Integrating interdisciplinary approaches is essential to deepen our understanding and mitigate threats to high-mountain lakes, ensuring the preservation of their ecological integrity and natural heritage for future generations. Engaging local communities and citizen scientists enhances data collection, promotes stewardship, enriches scientific knowledge, and fosters community involvement in environmental conservation.

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.