The TRANSFER project
The footprint of global change shows up in multiple indicators. As evidence accumulates, some paradoxes also emerge. At multiannual time scales, one intriguing aspect is why some ecosystems seem to follow more closely indicators of general atmospheric dynamics (e.g., CO2 increase, hemispheric mean annual temperature) than the local weather and deposition records. Pathways of mechanistic causality must exist that explain the apparent paradox. Probably, they are related to processes of a different characteristic reaction and renewal times. One of the systems in which the phenomenon has been observed is the plankton of remote lakes. The TRANSFER project aims to address this issue.
The planktonic system, which is very reactive and thus potentially able to follow closely the atmospheric fluctuations, is also influenced by two major reservoirs of materials and long residence time: sediment and groundwater compartments in the basin. Consequently, this project has the general objective to understand the link between atmospheric and plankton dynamics, and to what extent it depends on processes in the lake itself (subproject 1) and processes in the basin (subproject 2). The project aims to: i) clarify what are the best indicators of the planktonic communities to discern between atmospheric influence of energetic character (weather), material nature (fertilization) or synergy of the two; ii) study how internal nutrient load modulates the plankton dynamics at different time scales and link with atmospheric fluctuations in circumstances of low influence of the basin; iii) determine the role of subsurface and groundwater in the generation of surface flow to the lakes; iv) estimate the rates of biogeochemical processes occurring underground and how this affects the external load of nutrients to lakes; v) estimate the role of singular events of low frequency and high intensity, and their influence on the average internal, and external loads of nutrients; vi) provide an integrated view of the transfer of atmospheric fluctuations to the planktonic system of lakes in remote areas to understand the apparent paradoxes. We will use case studies and numerical simulations to address the problem. The experimental sites are in the Central Pyrenees, where the group has a long research experience, particularly in Lake Redon and the Ribera de St. Nicolau watershed in the Aigüestortes i Estany de Sant Maurici National Park. A collection of analytical (e.g., stable isotopes, molecular markers) and numerical techniques will be applied to studies that include: i) mesocosms experiments; ii) multiannual time series of planktonic, biogeochemical and weather data; iii) high-resolution sediment cores, iv) groundwater compartments and their reactivity; v) modelling of the transport from the basin to the lakes; vi) modelling of the coupling between atmosphere and sediment at multiannual scales and vii) modelling of the planktonic dynamics as a metabolic network.