Predicting differential species sensitivity in aquatic invertebrates - NERC GW4+ DTP project

This project is one of a number that are in competition for funding from the NERC GW4+ DTP. The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus six Research Organisation partners. The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science. For further details about the programme, please see http://nercgw4plus.ac.uk/.

Background

Chemical risk assessment for pollution control relies on data derived from tests performed on a limited number of species to predict the impact of pollutants on all species in an ecosystem.

To address this uncertainty, environmental managers often need to incorporate an arbitrary ‘safety factor’ (usually division of a toxicity metric, such as an LCx, ECx or NOEC by 100 or 1000) to account for species sensitivity difference when deriving safe chemical concentrations.

This is a naive approach. To improve the scientific basis for incorporating species differences into risk assessment, the capacity to provide a prediction of the actual sensitivity of an untested organism based on a limited number of measurements in a variety of tested invertebrate species would be a huge step forward.

This PhD project will seek to use genomic and physiological analysis top better understand how different characteristics make freshwater invertebrate species more or less sensitive to pollutant exposure

Project aims and methods

The project will use a range of experimental, data analysis and bioinformatic methods to address the sensitivity of different aquatic invertebrates to two chemical classes: namely, 1) Non-polar ’narcotic’ organic chemicals focusing on persistent hydrocarbon molecules that characterise oil pollution; and 2) Pesticides affecting nervous system function focusing on organophosphates and neonicotinoids.

Comparing species responses for chemical classes with different non-specific (hydrocarbons) and specific (pesticide) modes of action will allow you to tease apart the contributions made by different uptake, internal distribution and biochemical characteristics on species sensitivity. This will allow the following objectives to be addressed.

Objective one: Assess the sensitivity of aquatic invertebrate species from four taxa (crustacean, insects, annelid, mollusc) to three different chemical classes (hydrocarbon, organophosphate insecticide, neonicotinoid insecticide).

Objective two: Quantify chemical uptake to determine parent compound and metabolite concentrations at the target site (eg nervous system) in different species.

Objective three: Model and measure pollutant interactions with receptors using gene sequencing, alignment, homology modelling and experimentally validated molecular docking studies.

Objective four: Incorporate uptake rates, receptor analysis and species ecological traits into a system that links hydrocarbon and pesticide exposure to realised toxic effect.

CASE Award

The Centre for Ecology & Hydrology (CEH) is the CASE partner for this work. The two research groups (Kille and Spurgeon) have an established relation and track record of joint PhD supervision. Students will exploit training strengths and research infrastructure provided by both organisations with specific secondment at CEH being an integral component of the project.

This project builds on a funded collaboration between the University and CEH, NERC-funded project ‘Leveraging comparative physiology and genomics to predict species sensitivity: A novel framework for interspecies extrapolation in ecotoxicology’, which has developed and validated the approaches and methodologies underpinning the proposed PhD.

Training

You will learn experimental approaches in ecotoxicology including toxicity testing with a range of invertebrate species, use of radiolabel chemical to track uptake and distribution, as well as the use of a range of different gene and enzyme based biomarker measurements.

Staff in the CEH Genes and Markers in the Environment laboratories will train you in DNA sequencing techniques (including for next generation sequencing methods). Training in bioinformatics will be provided though hands on courses already in place at the University and available to all researchers as well as through contact with the Cardiff-based group.

The molecular modelling work to ascertain how chemical bind with putative receptor molecules will build on approaches that are already widely in use in pharmacology. These in silico ’molecular docking’ studies and methods for their experimental validation are already in refinement for receptors found in terrestrial annelids in NERC standard grant (NE/M01438X/1/) and the work of the student to extend their application to aquatic taxa will represent a near unique cross species assessment in ecotoxicology.