Programma della conferenza

Mediterranean infralittoral rocky reef ecosystems can undergo a distinctive regime shift, where the healthy state, characterized by macroalgal forests supporting rich and biodiverse communities that provide key ecosystem functions and services, are replaced by a degraded state, characterized by barrens formed by encrusting algae and showing low biodiversity. Sea urchins usually play a pivotal role in this process since, under certain conditions, they can significantly increase in number and favour, thanks to their grazing activity, this unwanted regime shift.  We propose an ecological, process-based mathematical model that describes the processes influencing the spatio-temporal dynamics of the algal cover, focusing on the interactions between primary producers, sea urchins (whose grazing activity mediates the competition between the two algal groups) and sea urchin predators (such as sea breams, Diplodus spp.), and how these can drive the shift from a macroalgae-dominated forest to barren and vice versa. Our model allows us to describe population dynamics of the species involved and biomass flows across the different trophic levels. It makes also possible to explore how different levels of exploitation, on both sea urchins and their predators, can trigger a possible shift from forest to barren, thus driving a re-organization of the community. Although more robust calibration and validation is needed to make the model fully operational, this modelling approach has the potential to inform management policies and conservation strategies. Eventually, we aim at refining and expanding the model to include the effect of climate change and ocean connectivity, towards a basin-scale analysis at the meta-community level.

The Baltic Sea is a crucial wintering site for seabirds, particularly velvet scoters (Melanitta fusca). Velvet scoter is rapidly declining, despite being one of the most abundant wintering sea duck in the Baltic Sea. Protection measures should consider information such as diet, diving behaviour, time-budget and wintering energy requirements for the planning and zoning of marine protected area. Therefore, this work provides an integrated approach for the evaluation of the seabed energy and the energy demand of velvet scoter wintering in the Lithuanian coastal waters in the Baltic Sea. Diet analysis, using stomach content from bycaught individuals, were used to identify key prey species. The time-budget and diving behaviour were assessed via direct visual observations and transmitters deployment, respectively. The visual observations assessed the frequency of six behavioural categories during the day (resting, locomotion, feeding, comfort, alert and social interaction). Transmitters data provided information such as dive duration, descend, bottom and ascend duration, as well as the daily number of dives and the depth distribution. Literature data were used to recalculate the energy values associated with each behavioural category, providing insights into the estimation of daily energy expenditure. Benthic samples, collected between April 2020 and July 2021, were analysed to assess the distribution and biomass of prey in the environment. Benthic biomass was then modelled using Random Forest and converted into energy values to evaluate seabed energy availability. Information on the foraging ecology of velvet scoters and other energy costs (thermoregulation, basal metabolic rate, etc.) were combined to determine the sea duck’s energy distribution. Ultimately, the integration of seabed energy availability and velvet scoter energy demands offers information for the zoning and prioritization of key feeding areas, which is essential for the conservation of this declining species in the Baltic Sea.

Biological invasions are constantly increasing globally, with freshwater ecosystems (rivers and lakes) among the most vulnerable. In these habitats invasive crayfish (Crustacea, Decapoda) have a significant ecological impact. The current study examined the population structure, as well as the spatial and temporal distribution of the invasive American crayfish Faxonius limosus in two subalpine lakes in northwestern Piedmont (Lake Orta and Lake Mergozzo) where its occurrence is well established. Littoral sampling covering a 1-year project (2021-2022) allowed us to measure, weigh and sex determine all collected individuals. Subsequently, the population structure was investigated to confirm whether 1) the invasive species' abundance (Hypothesis1- Hp1), 2) and its growth differ between the two lakes (Hp2);3) the potential use of invasive species to produce biofilm for sustainable food packaging as containment strategies (Hp3). This study found that total number of individuals caught were higher in Lake Orta (86) than in Lake Mergozzo (57) with a sex ratio M/F of 1.39 vs 3.07, respectively. However, its average Catches Per Unit Effort (CPUE) abundance in the two lakes was similar (Hp1). Individual growth was higher in Lake Mergozzo than in Lake Orta (Hp2). Producing crayfish-based biofilm from chitosan extracted from F. limosus exoskeleton may be a viable strategy for the species' containment (Hp3) at least in those countries where laws do not prevent their use and where reducing waste needs to become a pivotal practice. Our study is a valuable contribution to the deepening of knowledge on the ecology of F. limosus in the lakes of the Verbano area.

Forest litter is a critical component of soil ecosystem, providing habitats and food for a variety of organisms. Reducing erosion, conserving moisture and moderating temperature fluctuations, it acts as a protective layer for soils. Contextually, litter is a fundamental resource for soil microarthropods that, through feeding and shredding activity, contribute to litter breakdown and facilitate the nutrient access to plants and microorganisms. Despite their key role, researches regarding their community dynamics are still scarce. Therefore, the present research aimed to investigate changes in soil microarthropod community composition and trophy distribution under the main plant cover of the Mediterranean area such as pine (Pinus spp.), holm oak (Quercus ilex L.) and chestnut (Castanea spp.). Litter samples were collected and microarthropods were extracted and identified. Then, the relative abundance of microarthropods according to their trophy (detritivores, predators, omnivores and herbivores) was determined. The data revealed that: pine litter supported a community mainly composed by Prostigmata (38 %) and Oribatida (37 %) with higher percentage of detritivores (58 %); holm oak litter supported a community mainly composed by Prostigmata (42 %) and Oribatida (40 %) with similar partition between detritivores (49 %) and predators (49 %); chestnut litter hosted greater diversity in terms of species richness with higher percentage of detritivores (66 %). It can be supposed that litter quality and shape drive the composition of the soil microarthropod in terms of abundance of specific taxa and trophic role. In conclusion, soil microarthropod composition and functionality is strictly dependent on plant biodiversity exerting, in turns, effects on organic matter turnover.