The Dynamics of Freshwater Food Webs Under Multiple Threats

Aquatic ecosystems around the world provide critical services to humanity including freshwater, food resources and the capacity to store carbon and thus mediate climate change. Understanding how freshwater ecological communities respond to multiple simultaneous threats including temperature changes, runoff from agriculture,

invasive species and harvesting is critical to maintain the provision of these services. This PhD will focus on a unique long-term dataset from Lake Windermere on species interactions across more than Project Advertisement four trophic levels and among 50+ species. The PhD project aims to apply modern statistical modelling and food

web modelling methods to derive deep understanding of the mechanisms driving resilience and resistance to environmental change, or the lack thereof, in freshwater ecosystems. In addition to the modelling, the PhD will also aim to fill critical data gaps in lower trophic levels including phytoplankton and zooplankton functional groups.

Specifically, the objectives of the PhD are Obj1 - resolve functional groups, taxonomy and body size in zooplankton and phytoplankton to help align with core ecological theory linking body size, metabolism, production and foraging to biomass dynamics of species rich communities. Obj2 - Applying modern statistical models (Multivariate

Autoregressive models) to the time resolved Windermere data, with a focus on trophic cascades, invasive species effects, climate change, contaminants. This objective offers a collaboration beyond Sheffield and CEH, including Dr. Stephanie Hampton from University of Washington, USA, an expert in these models.

Obj 3 - Parameterise an established multi-trophic multi- species dynamical model across 5 trophic levels to explore whether ecological theory can predict the kinds of responses seen in real time series to invasive species, temperature change and contaminants. Additional opportunities exist to extend the work to include

the microbial community and to explore shifts in ecosystem function. The student will join an active research group using statistical and mathematical modelling using Julia and R prorgramming languages to answer major questions about how multiple simultaneous threats to ecosystems impact on the functions and services they provide. They will be part of

a supportive and productive lab in Sheffield and benefit from established relationships with the UK Centre for Ecology and Hydrology and external partnerships. This combination of training and research opportunities provides an excellent platform for reserach careers in and out of academia.