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

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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.