The overarching objective in the lab is to improve our understanding of freshwater ecosystems and how these are responding to global change. Doing so, we study contemporary changes in landform types, the distribution of species functional adaptations, and the interlinkage between landscape changes and ecosystem functioning. We combine observational field data, museum collections, public data resources, and modeling to describe the reciprocity between biodiversity and freshwater in the landscape.

Our research has two foci: In a general ecological perspective, we work towards understanding how functional adaptations to life in freshwater environments structure species distributions and how such adaptations are linked to climate and geology. In an anthropogenic perspective, we focus on documenting human impacts on freshwater systems and how such impacts challenge the integrity and future of freshwater functions and services.

Functional adaptations to life in freshwater

What constraints does the environment have on functional traits in freshwater organisms and how does the freshwater trait-space compare to terrestrial counterparts? We explore aspects of functional ecology and biogeography of species adapted to freshwater habitats. Documenting unique adaptations to the freshwater environment is essential if we are to understand current and future ecosystem functions in lakes and rivers. It also allows us to predict to what extent freshwater organisms follow terrestrial responses to human pressures, such as climate change, contra pathways unique for the freshwater environment. We address these questions using trait variation in freshwater plants and aquatic insects both at local gradients within a single system and across the globe. 

Examples of our work:

Iversen L. L., et al. (2019): Catchment properties and the photosynthetic trait composition of freshwater plant communities. Science

Iversen L.L., et al. (2019): Sexual conflict and intrasexual polymorphism promote assortative mating and halts population differentiation. Proceedings B.

Iversen L.L., Rannap R., Briggs L., & Sand-Jensen K. (2017): Time restricted flight ability influences dispersal and colonization rates in a group of freshwater beetles. Ecology and Evolution

Spatial equilibrium dynamics in aquatic systems

Freshwater science has a history of research targeting ecosystem stability and links between biodiversity and the environment. Several general concepts, such as alternative stable states and the river continuum concepts, originates from the extensive literature on site specific freshwater biology. Recent advances are advocating for an extension of site-specific approaches incorporating landscape level dynamics into the equitation. We are especially interested in the downscaling effect of landscape level factors on local biodiversity – environment relationships. This includes questions such as: How does local environmental selection change across connectivity and stability gradients? and how can we use novel disequilibrium models to advance existing freshwater monitoring programs?

Examples of our work:

Iversen L.L., Jacobsen, D., & Sand-Jensen K. (2016): Are latitudinal richness gradients in European freshwater species only structured according to dispersal and time? Ecography

Gaüzère P., Iversen L.L., Seddon A.W.R., Violle C. & Blonder B. (2020): Equilibrium in plant functional trait responses to warming is stronger under higher climate variability during the Holocene. Global Ecology and Biogeography

Iversen L. L., Rannap R., Kielgast J., Thomsen P.F., & Sand-Jensen K. (2013): How do low dispersal species establish large range sizes? – the case of the water beetle Graphoderus bilineatus. Ecography

Global change in freshwater systems

Changes in freshwater ecosystems are closely coupled the rise of the Anthropocene, rivers and their floodplains alone are home to ~35% of the world’s population. They are economically vital, highly biodiverse, and influence global biogeochemical cycles. However, a number of anthropogenic stressors, including large-scale damming, climate change, pollution, and sediment mining, challenge their integrity and future, as never before. Together with a diverse group of scientists, spanning from physical geographers to conservation scientists, we explore contemporary landscape patterns in freshwater systems across the globe. The work includes landscape scale mapping of changes of deltas in the Arctic as a response to climate change, predicting sand mining across urban growth in Africa, and modelling human pressures on biodiversity across threats in the world’s big rivers. 

Examples of our work:

Bendixen M., Best J., Hackney C., & Iversen L.L. (2019): Time is running out for sand. Nature  

Bendixen* M., Iversen* L.L., et al.(2017):  Delta progradation in Greenland driven by increasing glacial mass loss. Nature

Harfoot M.B. J., …Iversen L.L…. et al. (14 authors) (2021): Using the IUCN Red List to map threats to terrestrial vertebrates at global scale. Nature Ecology and Evolution