Developing Two Non-invasive Survey Methods for Freshwater Ecosystems
: Environmental DNA and Ecoacoustics

  • Jack Greenhalgh

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

Globally, freshwater biodiversity has declined by 81% in the last 45 years. Furthermore, wetlands are disappearing three times faster than rainforests. In the UK, 75% of ponds have been lost due to land-use change in the last century. It is therefore imperative to act quickly to conserve freshwater biodiversity. Central to the effort to conserve biodiversity is the effort to monitor biodiversity. Many conventional survey methods have been developed to quantify trends in biodiversity, however, they are often labour-intensive and invasive. Two novel non-invasive survey methods, environmental DNA (eDNA) and ecoacoustics, have been shown to exploit an aquatic medium to effectively survey marine biodiversity due to the wide transport of free floating DNA and the propagation of sound waves underwater. In this thesis, I explore the use of eDNA and ecoacoustics for surveying freshwater biodiversity. I report the use of eDNA-based methods to detect the invasion fronts of an advancing signal crayfish (Pacifastacus leniusculus) population in Yorkshire, UK. In addition, I use eDNA-based methods to map the distributions of invasive and endangered crayfish in Norfolk, UK, and evaluate the trade-off between reactive and proactive strategies to inform crayfish conservation. I conduct a systematic review of the freshwater bioacoustics literature and identify promising areas for future research. In addition, I co-develop the first standardised survey protocol for the collection of acoustic data from small waterbodies, and establish an open-access online repository for freshwater soundscape data. Next, I explore the diel acoustic activity cycles of temperate ponds, relate acoustic complexity to macroinvertebrate composition, and suggest guidelines for survey design. Finally, I explore the use of field recordings as a powerful tool for public engagement and science communication.
Date of Award24 Jan 2023
Original languageEnglish
Awarding Institution
  • University of Bristol
SupervisorGareth Jones (Supervisor) & Martin J Genner (Supervisor)

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