Evaluating biodiversity impacts of beaver reintroductions on invertebrate and vertebrate communities using environmental DNA

Project Description

Biodiversity is being lost at an unparalleled rate, particularly in freshwater ecosystems (McLellan et al., 2014). Reintroduction of keystone species such as beavers is considered part of the solution to the freshwater biodiversity crisis. Beavers, which were common in the UK until the 16th Century, are ecosystem engineers; shaping their habitat by felling trees and building dams, creating nutrient rich ponds, and slowing the flow of water. A primary motivation for reintroducing beavers is to create heterogeneous habitats that support novel communities of animals and plants compared to the surrounding landscape. Case studies on beaver impacts have previously focused on key taxa or taxonomic groups and demonstrated that many, but not all species benefit from beaver activity (reviewed in Stringer and Gaywood, 2016). Beaver reintroduction is gaining traction throughout the UK, for both improving biodiversity and Natural Flood Management, with reintroduction programmes in more than 10 counties, and beavers are naturally expanding their ranges (Wilson et al., 2020). However we still have a lot to learn about the impacts of beavers on wider biodiversity across different landscapes and spatial and temporal scales. Beaver activity is highly dynamic, and impacts are therefore predicted to be dependent on the surrounding landscape, and to change over time. Almost all of our knowledge of beaver impacts in the UK comes from excellent case studies on the River Otter in Devon, and Tayside in Scotland. While these case studies are from two very different habitats, they are not representative of all the current or potential beaver habitats in the UK. A holistic approach to understanding beaver impacts, both in terms of habitats and taxonomic groups studied, is needed in order to determine where beaver reintroductions are likely to be most beneficial, or potentially detrimental to biodiversity.

Environmental DNA (eDNA) analysis is revolutionizing the field of biodiversity monitoring, providing a cost-effective method for surveying all biodiversity rather than focusing on a few priority species (Lawson Handley, 2015, 2020; Harper, et al., 2019). Organisms release eDNA into the environment for example via shed cells, waste material or decaying matter. eDNA can then be captured by sampling water, soil, or air - without causing harm or disturbance to wildlife. eDNA metabarcoding is a rapidly emerging technique for generating millions of DNA sequences from a single sample; enabling researchers to describe entire communities of microorganisms, animals and plants. Our group at the University of Hull has pioneered this method for describing vertebrate and invertebrate communities in lakes, rivers and ponds, and demonstrated that it is a powerful tool for describing and studying impacts on biodiversity, and for evaluating ecological status of water bodies (e.g. Hänfling et al., 2016; Harper et al., 2019; 2020; Lawson Handley et al., 2019; Sales et al., 2020).

This PhD studentship will directly address research priorities identified by Natural England, using environmental DNA (eDNA) metabarcoding to describe the vertebrate and invertebrate communities associated with beaver habitats at local to catchment scales. In addition to addressing questions about beaver impacts, the project will ground-truth the use of eDNA to answer biodiversity questions at large scales, and provide important lessons for future eDNA work conducted by Natural England.