A Novel Framework for Predicting Emerging Chemical Stressor Impacts in Complex Ecosystems

Freshwater ecosystems provide critical ecosystem services that underpin human societies and wellbeing: including water purification, carbon capture, and the maintenance of sustainable fisheries. However, these ecosystems are under an increasing array of threats, both in the UK and worldwide, especially from a wide range of new and emerging chemical stressors (e.g. novel antibiotics and pesticides). Freshwater biosciences and applied ecology are under-equipped for dealing with these new threats: the evidence base is lacking, there is often little or no mechanistic understanding, or predictive capacity for anticipating how these novel chemicals will operate in the real world. This is particularly true for the ecosystems of the future that are being reshaped and constructed by climate and other environmental changes. Our project will address all these shortcomings by taken a radically different approach from the classical biomonitoring and ecotoxicology tools that have dominated for many decades. We aim to unearth the general rules by which emerging chemical stressors operate through, and alter, networks of interacting species - from microbes at the base of the food web, through to apex predators in the fish community at the top. This will involve the development of indicators of both proximate pollution, as the chemical first enters the biological system (commonly as a new food source for microbes), and also of its indirect effects as its impact propagates through the food web. For instance, we will be able to answer questions such as: if a new insecticide wipes out the invertebrates in the middle of the food web, does this trigger blooms of nuisance algae as they are no longer kept in check? To achieve this, we will develop a new suite of methods at the ecosystem level that combine lab and field experiments to detect the causal mechanisms that we currently do not understand. The experiments will be combined with mathematical modelling to predict ecosystem-level impacts. We will address both, contemporary ecosystems that could be under imminent threat from new chemical stressors, and ecosystems of the future that will emerge under different scenarios of land-use and climate change. This will provide a completely new paradigm in chemical stressor monitoring, based on using first principles to derive a novel means of predicting "ecological surprises" that commonly arise due to the inadequacies of our current simplistic approaches when dealing with the true biocomplexity of natural systems. Our scope is for our approach to serve as a diagnostic tool for management, with research findings, for example, supporting the selection of mitigation options that deliver reduction of ecological effects. This paradigm shift will allow far more robust predictions and therefore more informed management decisions about the freshwaters of the future. The work will bring together the field of pure and applied ecological science, to the mutual benefit of both sets of disciplines. Our proposal represents the first steps along this path to the more multidisciplinary perspective that is going to be critical for dealing with future threats to our ecosystems - from emerging chemical stressors in freshwaters to the growing list of other environmental threats looming on the horizon. Because the approach is general, it will not only pave the way for the next generation of ecological assessment in freshwaters, but it can also be adapted for applications in marine and terrestrial ecosystems.