Conference Agenda

Macrophytes are a key component of freshwaters and fundamental mediators of their functioning. However, native macrophytes are facing a worldwide decline due to multiple pressures: one of the main threats is the spread of invasive species. Hydrilla verticillata is a submerged macrophyte native to Asia and Australia, but it’s invasive in other continents. Egeria najas is also a submerged macrophyte native to South America, and it’s co-occurring with H. verticillata along the Paraná River (Brazil). This study aims to understand the adaptive responses of E. najas in habitats invaded by H. verticillata, by comparing functional and environmental niches of monospecific and mixed populations. The two species, though structurally similar, show a distinct niche based on leaf functional traits. Both become more plastic when co-occurring, adopting more competitive strategies. This suggests that they are highly efficient and can exploit the available resources differently, allowing their simultaneous presence. Besides, H. verticillata tends to occupy a subset of E. najas’ environmental niche, indicating a more generalist behavior of the latter species, explaining its success despite the presence of the invasive. Overall, a wide variability in terms of functional traits expression and environmental tolerance seems to ensure the persistence of the native species.

The genus Isoëtes includes iconic plants, characteristic of a wide range of ecosystems including nutrient-poor aquatic waterbodies. They are wetland obligates which have suffered severe losses globally over time mainly due to alterations and loss in colonized habitats. This is due to their sensitivity to habitat alteration and eutrophication of water and sediment. Despite this, a global review of the ecological knowledge about aquatic species belonging to this genus is missing, and overall, we know very little at the global scale. An assessment of aquatic Isoëtes ecology is therefore important, particularly for a better understanding of what the main threats to their conservation are. Through a global, collaborative initiative a first global ecological assessment focusing on aquatic Isoëtes was carried out. It includes a literature review, an extensive new database on Isoëtes distribution and growth conditions, and ecological niche analyses. We first compiled a global aquatic Isoëtes database including all known environmental data collected between 1935 to 2023 (for a total of 1880 georeferenced records). We then used ordinations to quantify ecological niches and environmental drivers for a subset of species. Both well-established findings and unexpected results emerged, opening new perspectives for the conservation of aquatic Isoëtes.

Spring ecosystems are hotspots for biodiversity, often connecting aquifers to headwater streams. In this work, we investigate the functional role of periphyton biodiversity on carbon processing, in spring-fed streams of the southeastern Alps. We sampled four sites in the Adamello-Brenta Nature Park (Trentino, Italy), from June to August 2023, and monitored changes in periphyton biofilms' structural characteristics and carbon cycling dynamics, both in the spring head and further down into the spring-fed stream. We collected periphyton for taxonomic determination, measured spring-stream metabolism by deploying O2 sensors, and measured dissolved CO2 concentration with a gas analyzer. We found that spring-fed streams have high CO2 concentrations, and that spring periphyton biofilms biodiversity could have an important role in assimilating CO2 from the supersaturated waters emerging from the aquifer before it is degassed to the atmosphere. Conserving spring biodiversity thus becomes an important strategy also for climate change mitigation.

Peatlands are ecologically important sites for carbon sequestration, provide a valuable refuge for many sensitive threatened species of the Alpine foothills, and can be hotspots of biodiversity. The Fiavé Nature Reserve, a Natura 2000 site, is an alkaline fen (main occurring vegetation, Caricion davallianae), and includes the UNESCO World Heritage Site of the Bronze-Age pile dwellings of Fiavé. This study aims to assess the influence of surrounding farmlands on the quality of local biotopes using diatoms, chemistry, and vegetation (mapped with drones) as indicators and proxies. For this purpose, three 50-cm deep peat cores (in the Alps roughly representing the last 500 years), and surface and piezometer water samples were collected. Peat cores were cut while frozen into 3-cm samples, which were characterized from the physical and chemical point of view. Moreover, subsamples were processed to create permanent diatom mounts. Diatoms were identified, counted, and evaluated from the perspective of a link to the concentration of nutrients and a possible negative impact of eutrophication or chemical pollution in the studied area. The results will also be used to inform and support best management practices, such as the establishment of buffer zones.

Peatlands are highly vulnerable and play a crucial role in carbon sequestration and biodiversity conservation. Cattle grazing and trampling contribute to peatland degradation and pose a significant threat to habitat integrity and biodiversity, especially in the southeastern Alps, where mires are habitats at the southern margin of their global distribution. The main objective was to examine the impact of grazing on the physical, chemical, and biological characteristics of peat, with a focus on diatoms to gain insights for a sustainable management and conservation of these habitats. Seven 50-cm deep peat cores were collected from mires located in the Adamello-Brenta Nature Park (Trentino, Italy) along a grazing-induced disturbance gradient. Results revealed that grazing, primarily affected the upper 15 cm of the peat resulting in increased density, reduced water content, elevated nitrogen concentration from cow manure. Over 200 diatom taxa were recorded and several of them fall under threat categories in the Red List for central Europe. Highly-grazed areas exhibited a higher percentage of eutraphentic species, linked to increased nutrients from cattle manure, and aerial species, which survive in environments with unstable water availability. This research provides useful indications on the effects of grazing in terms of biogeochemical cycles and nature/habitat conservation.

Cultural and economic attitudes of societies have always impacted freshwater ecosystems’ conservation. Today the ecology and biodiversity of groundwater and springs are more studied, instead of their interconnection with culture, that has been a low priority. Analysing different case studies and the current literature of springs in the global mediterranean climate zones, cultural and socio-economic impacts on these unique aquatic ecosystems and their ecohydrogeology were examined in depth. The focus was on deep traditions, history, religion, law, economy of Mediterranean springs, and on the constantly growing and frequently unsustainable demand of these resources for water supplies, agriculture, energy, causing their degradation and loss, in particular happening when economic values equal or exceed cultural values. Therefore, the achievement of an improved and sustainable stewardship of springs and their aquifers is an important goal to reach, together with an essential conservation challenge for modern society dealing with climate change worldwide.