Nutrient and organic material constraints on management success

Experimental Stream site in Netherland

The effects of climate-driven changes in nutrient spiralling and organic material processing on the success of management strategies in rivers, on the structure and functioning of river ecosystems, and on changes in river biodiversity will be examined in REFRESH. The focus will be on nutrients and organic matter in relation to the construction of riparian buffer strips/floodplain wetlands to establish water retention along small-sized lowland streams. Indicators reflecting key nutrient and organic material conditions will be integrated in a shading 'low flow/drought' nutrient/organic material load experiment. In the controlled field/mesocosm multiple stress experiments, the combined effects on algae, macroinvertebrates and macrophytes will be studied and the effects on a number of ecosystem and physico-chemical parameters will be measured. 

For lakes REFRESH will identify the effects of climate-driven changes in nutrient dynamics and organic matter processing on (i) the structure, function and biodiversity of lake ecosystems; (ii) the successes of management measures in lakes; and (iii) interactions between temperature and multiple hydrological stressors in natural and eutrophied (restored) lakes.

Nutrient enrichment in Turkish lakes

We will (i) conduct experiments to elucidate the effect of short and long-term loading of humic substances on lake ecosystems; (ii) analyse the combined effects of temperature, hydraulic retention time and nutrient and organic loadings on structure and function of lakes and reservoirs using monitoring and palaeoecological records; (iii) test existing and develop new more advanced models that can handle multi-stressor effects on lakes and reservoirs; (iv) use selected models to run scenarios of the interactive effects of climate and nutrient and organic matter loading on lakes and reservoirs and potential mitigation effects. 

Left: Algal bloom in a lake caused by nutrient enrichment.

Stream and floodplain restoration project in the Netherlands

For riparian wetlands we will assesses the interactions between climate-driven changes in temperature and flooding with land-use driven changes in nutrient loading. The potential effects of climatic changes cannot be studied independently from predicted land-use change effects, in particular the effect of increased nutrient loading to aquatic and riparian systems. For each region we will compare two sites in catchments with moderate and heavy levels of nutrient enrichment. The replication of these experiments between two sites differing in nutrient loading will help identify interactions between changes in temperature, inundation and nutrient loading.

RightStream and floodplain restoration project in the Netherlands (Photo: Merel Soons)