How do freshwater ecosystems react to changing environmental conditions and to what extent can these changes be captured in the dynamics of eco-evolutionary processes? The project REES ('Rhine Eco-Evolutionary System') aims at the long-term assessment of eco-evolutionary interactions in the Rhine as a limnic habitat under consideration of diverse associated water bodies. The study area includes the main flow channel of the Rhine (km 845, North Rhine-Westphalia), as well as Rhine oxbows, Rhine water-fed gravel pit lakes in ecological succession and the surrounding floodplain (Rees, district of Kleve). The Ecological Research Station Rees-Grietherbusch of the Institute of Zoology (University of Cologne) and the Nature Conservation Center District Kleve e.V. form the central infrastructure of the study area. In addition, the Ecological Rhine Station of the University under the direction of Prof. Dr. Arndt is also associated to the project, which enables direct sampling and experimental recording of the main Rhine flow channel. The extensive system of standing and flowing freshwater bodies covered in the REES study site allows the investigation of dynamic variations in biodiversity composition at all levels, from species diversity of communities to genomic diversity at the molecular level of individuals and populations. Along a selected trophic cascade, representative species will be long-term observed and analyzed ecologically and especially also (population-)genomically. The incorporation of ecological genomics is the core aspect of this LTER-D project, which is intended to capture the feedback of evolutionary changes on the ecological system. Population genomic approaches can be used to infer both evolutionary and ecological processes from genomic data. To cope with the dimension of this project, REES is designed as an interdisciplinary collaboration project and currently counts seven project partners with corresponding subordinate projects.

The site is a revitalized young steppe habitat patch, dominated by fescue (Festuca rupicola). The average altitude is around 100 m. The site is a grazing spot and it was recently used for the reintroduction of the European ground squirrel (Spermophilus citellus) to the area after 70 years. Other important species present at the site include Vojvodina blind mole rat (Nannospalax (leucodon) montanosyrmiensis) and Spring meadow saffron (Bulbocodium versicolor).

The Presidential Estate of Castelporziano stretches itself over an area of about 6100 ha and is located approximately 24 km from the city of Rome. The territory is characterized by remarkable natural features. It shows most of the typical Mediterranean ecosystems (relict strips of lowland forest with hygrophilous vegetation, deciduous and evergreen mixed oak woods, Mediterranean scrub, dune vegetation). Until recently (2019), there were large surfaces of stone pine unfortunately destroyed by the combined action of alien pest Toumeyella parvicornis with Tomicus destruens, the main pest of Mediterranean pine forests. Inside the Estate, there are two Special Areas of Conservation (SACs): one concerning the coastal strip (IT6030027) and the other one concerning hygrophulous oak-woods (IT6030028). In addition to including the two SACs, the Estate is in its entirety Special Protection Area (SPA - IT 6030084). From a botanical point of view this area, together with the neighbouring Castelfusano territory, represents what remains of the vast forest system that covered the entire delta of the Tiber and the surrounding areas. The land is mostly flat, but in the North there are modest reliefs that are not higher than 85 m. on sea level. A complex set of ancient dunes and a chain of more recent dunes stretch out along the coastline. There are many temporary and permanent natural pools and wetland areas with seasonal floodings caused by meteoric water and groundwater, which usually dry out during summer and represent sites with the greatest biodiversity. From an ecological point of view, those “relict wetland areas” play actually a very important role for biodiversity because of plant species which are typical of hydrosoil and in the past were widespread but have now almost disappeared.

The Seine estuary is a megatidal estuary located in northern France. It is the third largest estuarine ecosystem in the country after the Gironde and Loire along the French Atlantic coast; its waters flow into the English Channel. The geographical zone of influence of the Seine estuary runs from just upstream of the Poses dam, at the limit of the tidal penetration into the estuary — 160 km upstream of Le Havre —to the eastern part of the Bay of Seine. It can be divided into three sections: the fresh water upstream section (125 km), the mixing zone characterized by varying salinity levels (35 km), and the marine downstream section under the influence of the Seine River. The megatidal regime generates a turbidity maximum in the mixing zone (middle estuary) between the marine and fluvial sections of the estuary. The Seine estuary is a typical estuarine ecosystem: highly stressed by natural fluctuations and anthropogenic pressures, and hosting a rich ecological system. The Seine valley and its estuary are of major economic importance for France, with the presence of two maritime ports. It’s watershed (79,000 km2) is the home to 17 million people, and accounts for 50 % of the river traffic in France, 40 % of the country's economic activity, and 30 % of its agricultural activities. In addition to the Greater Paris area (> 11 million inhabitants), which contributes heavily to the Seine estuary's upstream inputs, two other major river settlements — Rouen (500,000 inhabitants) and Le Havre (300,000 inhabitants) — are maritime ports of international importance. Due to economic development, the Seine estuary has been subjected to major hydrodynamic, ecological, biogeomorphological and biogeochemical changes. The importance of studying the effects of anthropogenic impacts on estuarine ecosystems has increased in the last decade, especially under the Water Framework Directive, which aims to achieve “good environmental status” of all European water bodies.