Connecting Aquatic Food Webs to Land Use Change

The land around lakes and rivers has long been known to funnel energy and nutrients downstream to support the growth of aquatic organisms. However, a pressing question is how the reliance on these resources and subsequent productivity of aquatic organisms changes as surrounding lands are altered by human activities. In 2014, we published the first study demonstrating how the productivity of entire lake food webs varied with the type and amount of surrounding land cover. The paper was highlighted by the UN in their landmark Freshwater, Fish, and the Future report and was featured on an episode of the Canadian Broadcasting Corporation’s (CBC) flagship TV series The Nature of Things. CBC Kids even broadcast a summary of the paper for children.

The 2014 study further catalysed intense debate on the importance of terrestrial resources between lab and field studies that culminated in a global synthesis that we led with funding from UKRI NERC. The work provided the first global test for cross-ecosystem resource fluxes in lakes and resolved the debate once and for all. The novel methods behind these papers led to other important discoveries linking terrestrial base cation depletion to dramatic changes in lake food webs, patterns of human land use to microplastic pollution, and forest disturbances as levers on land-water nutrient cycling.


Climate-Driven Shifts in Terrestrial Inputs Direct the Fate of Aquatic Carbon

With funding from UKRI NERC, we established the RELATED experiment to predict how future shifts in terrestrial inputs associated with climate change will impact aquatic carbon cycling. Our approach to manipulate lake sediments in the field was entirely novel. We used RELATED to show that northward migration of plant species could enhance methane concentrations in lake sediments by >70% by changing the chemistry of decomposing litter. This newly discovered climate feedback between shifting vegetation and microbial decomposition was highlighted in the film Earth Emergency narrated by Richard Gere and where we appear alongside leading climate scientists and activists such as Greta Thunberg, His Holiness the Dalai Lama, and Jane Fonda.

We later used RELATED to discover that greenhouse gas concentrations in lakes were more coupled to the chemical than microbial diversity of the environment and small-scale environmental variation was itself important for the development of microbial communities. We are now working to understand how carbon cycling depends on the molecular diversity of organic matter at a continental scale.


Climate Warming Restructures Food Webs

We have advanced understanding of the long-term impacts of climate warming in natural ecosystems, including how it restructures the biomass and phenology of lake food webs and evolutionary arms races between trees and seed predators. By co-leading an international NERC-funded network on forest reproduction, we have tracked how forests are adapting to climate change.

Recently, we have returned to interdisciplinary Arctic research to identify the consequences of thawing permafrost for the food webs that support human well-being. We discovered that that despite more than half of the dissolved carbon in shallow groundwaters of peatlands being >1,000 years old, this material was largely absent from downstream food webs. We are now tracking how microbes interact with "ancient" carbon released by thawing permafrost.


Explaining Why Biodiversity Varies Across Time and Space

One of the most enduring mysteries in biology is why species vary so greatly in number across the Tree of Life and across geographic space. Our group has discovered that uneven rates of evolution explain why some flowering plant groups are extremely speciose (highlighted in Nature), identified the large-scale evolutionary processes that create global biodiversity hotspots, and revealed why mountains are rich in biodiversity. Our research has also generated more practical knowledge on extinction threat that can inform species conservation. To transfer knowledge into practice, we closely engage with world leading biodiversity conservation organisations at the Cambridge Conservation Institute. We are now applying these approaches and tools to predict how species are adapting in response to global change and the implications for ecosystem health, such as water quality.