Lakes characterize the Arctic landscape accounting for up to 90% of the total land surface area. Collectively they may influence biogeochemical dynamics at regional and global scale and provide a variety of key ecosystem services, being critical habitats for unique species, atmospheric C sources/sinks and links of nutrients between terrestrial and marine systems. Nutrient inputs in Arctic lakes may be affected by changes in snow and vegetation cover and guano of migratory birds associated with climate warming, with implications on biodiversity, food web structure and functioning. Thus through field experiments and satellite data, the aim of this project is to test the hypothesis that the seasonal snow cover and abundance of migratory birds have a crucial role in determining C and N availability and fate in high Arctic lakes. Nutrient burial in sediments and soil, transfer along the food web and/or recycling into the atmosphere will be assessed. Samples for C and N stable isotope analysis and high-resolution satellite and field images for bird abundance, snow and vegetation cover will be collected in the area of Ny-Alesund, Svalbard. In addition short- and long-term decomposition experiments will be performed to evaluate the rate of nutrient release in water column. The project will develop a novel interdisciplinary approach applicable across the whole Arctic. Results will add valuable information to international research actions, including the European iCUPE and Terrestrial Ecology flagship NySMAC. They will provide important contribution for hydrological and ecological studies of the Arctic ecotone between terrestrial-freshwater habitats, and a necessary baseline of future monitoring and conservation plans. Datasets, maps and technical reports on methodologies developed during the project will be made available to the scientific community, being of interest for studies carried out in these extreme environments, which are also the most vulnerable to climate change.
Anticipating effects of climate change on nutrient cycling in Arctic lakes is necessary to conserve Arctic biodiversity and ecosystem services provided to Arctic human populations and at the global scale. This project will provide mechanism-based evidence on effects of seasonal snow cover and migratory birds on the origin, quantity and fate of nutrients fueling Arctic lake ecosystems. The combination of field measurements, experiments, in situ and satellite image acquisition, and data modelling for the study of lake ecosystems represents a scientific novelty both in polar regions and at lower latitudes. Such interdisciplinary approach will enable to understand how and how much the changes in the above mentioned factors will affect the origin and amount of nutrients stored in soil, sediments and primary producers, as well as the functioning of aquatic communities responsible for nutrient recycling into the atmosphere.
Isotopic analyses of terrestril soil and primary producers, bird feces, aquatic sediments and primary producers and consumers will provide an unprecedented characterisation of nutrient inputs and transfer in Arctic lake watersheds, clarifying their dependence on abiotic (snow melting) and biotic (migratory birds) factors affected by climate change. Field experiments will provide up-to-date organic matter decomposition rates, enabling comparisons across the Arctic and with ecosystems at lower latitudes. At microbial level, the experimental approach will furnish novel information on metabolic organic matter remineralization rates in Arctic lakes. These factors determine the fate, extension and rates of organic matter that can be hydrolyzed before the incorporation in new biomass, mineralization to CO2 or burial in sediment, with profound impacts on carbon and nutrient cycles.
Snow cover distribution will be derived using new generation satellite data (Sentinel 2). Satellite data will be merged with terrestrial images taken from the automatic instrumentation available in the study area. The terrestrial images will be both new and derived from the iCupe project, enabling a continuous monitoring of the distribution of the snowpack area. This will help to determine the beginning of the melting season, and to monitor the evolution of vegetation cover. Products of image processing will be integrated with field data to quantify the contribution of snow melting (Snow Water Equivalent, SWE) to the hydrological cycle, as a main driver of nutrient cycling in watersheds.
Produced data and maps will provide an important contribution for hydrological and ecological studies on Arctic terrestrial and freshwater ecosystems, and a necessary baseline to inform future monitoring and conservation plans. Datasets, maps and technical reports on methodologies developed during the project will be made available to the scientific community, being of interest for studies carried out both across the Arctic and in Antarctica.
DELIVERABLES: Within the two years of the project 1) N and C isotopic and elemental composition of abiotic and biotic components of high-Arctic lake ecosystems differing in seasonal snow cover and nutrient inputs by migratory birds will be quantified and maps describing spatiotemporal variations will be produced. 2) Counting of bird fauna colonizing lake watersheds will be performed and data made available to international monitoring networks. 3) Nutrient concentrations will be measured in different lakes and related to snow cover and bird fauna abundance. 4) Experimental measurements of organic matter decomposition rate will be produced through standardised protocols, enabling possible comparisons with other Arctic regions and ecosystems at lower latitudes. 5) Snow cover, vegetation distribution, NDSI and NDVI maps will be derived from satellite high resolution images (Sentinel 2). This will allow: 1. the identification of the main processes and associated watershed properties explaining observed variability in nutrient inputs, and 2. to support modelling of expected impacts of climate change on nutrient load and recycling in lakes.
Seminars for University students and for middle and high school students will be organized regarding ecological effects of climate change and Italian scientific activities in the Arctic. A dedicated web site will be set to disseminate results. Scientific publications on ISI journals and participation to national and international congresses will complete the dissemination of results.