Marianna Soler and Xavier Casamitjana participate in the 8^th Meeting of the European Pond Conservation Network Workshop (EPCN), held in Torroella de Montgrí (Girona) from 21 to 25 May 2018.

The EPCN is organized by the Aquatic Ecology Institute of the University of Girona with the support of the Museu de la Mediterrània (Mediterranean Museum) and the local government of Torroella de Montgrí. The meeting focuses on ecosystem functioning and services, including metacommunities, biodiversity, carbon balance, management and restoration, and global change, among others.

Dr. Soler contributes with the oral presentation entitled “Particle size segregation of turbidity current deposits in vegetated canopies”. This research was conducted within the FragmentUm project by Marianna Soler, Jordi Colomer and Teresa Serra, members of the Environmental Physics research group, in collaboration with Andrew Folkard from the Lancaster University. In this study, the authors state that interactions between ecology, hydrodynamics and sediments play central roles in the evolution of coastal and freshwater ecosystems and landscapes. They aim to characterise interactions of a specific hydrodynamic phenomenon – turbidity currents – with vegetation and sediment dynamics. The authors measured hydrodynamics and sediment deposition rates when turbidity currents flowed into plant canopies in a lock-exchange flume experiment. In all cases, on entering the vegetation canopy, the turbidity current was initially inertially-dominated, but subsequently became drag-dominated. In the inertial regime, there was no size segregation in the deposited material. In the drag-dominated regime, the deposited material became increasingly dominated by fine sediment, at a rate dependent on the vegetation type. The size segregation of deposited sediment is posited to have important consequences for substrate evolution, which in turn may affect vegetation growth. Thus, these findings point to a non-linear feedback mechanism between the spatial heterogeneity of vegetation canopies and that of the substrate they help to engineer.

On the other hand, Dr. Casamitjana gives the presentation entitled “A one dimensional model as a tool to predict the hydrological regime of three coastal lagoons in la Pletera salt marshes”. This study was conducted in collaboration with members of the Department of Environmental Sciences and the Institute of Aquatic Ecology of the University of Girona. The authors used the one dimension model GLM (General Lake Model) to assess the water balance and salinity dynamics of two natural lagoons and a new lagoon built in a Life Restoration Project in 2002. GLM computes vertical profiles of temperature, salinity and density by accounting for the effect of inflows and outflows on the water balance, mixing and surface heating and cooling. Since the model is one-dimensional, it assumes no horizontal variability. The model was initially built as a project within the Global Lake Ecological Observatory Network (GLEON) to provide a computationally efficient lake modelling platform. Results show that the model reproduces well the variation of salinities in the lagoons. In the old natural lagoons, the inflows after the main dry periods show higher salinities than sea water, and similar to those observed in the bottom of the lagoons during dry periods. Differences in salinity among lagoons could be explained not only by a distinct ratio S/V, but also by a slightly higher water circulation in the built lagoon. This knowledge poses new research challenges, such as to understand nutrient dynamics in this aquifer-lagoons system, or how climate change will modify the water budget and salinity dynamics in La Pletera lagoons.

Both studies have been conducted within the framework of the “Water Quality and Particles Transport” research line of the Environmental Physics group.