PhD Research - Invasive Species and In-stream Infrastructure

Invasive Species

Invasive species (those that are transported outside their native range by human activity and have significant negative impacts) are one of the greatest threats to global biodiversity. Their introduction can lead to the extirpation and extinction of native species through a variety of mechanisms, and recent studies have suggested that invasive species are a driving factor in 33% of animal and 25% of plant extinctions. Alongside the significant ecological impacts, the introduction of invasives can lead to a loss of ecosystem services and significant economic costs (up to £1.6 billion per annum in the UK). These impacts are likely to grow in the future, as climate change and increasing globalisation facilitate higher rates of introduction and establishment.


Invasive Species in Freshwater

Freshwater ecosystems are particularly vulnerable to invasion due to a number of unregulated sources of invasive species (e.g. aquarium release, ballast water, aquaculture etc.). Furthermore, the impacts of invasive species are more severe in freshwater systems, as hydrological and biotic isolation leads to higher levels of endemism and a greater risk of extinction. Consequently, invasive species are recognised as a key threat to freshwater biodiversity in several key reviews, although a lack of effective management techniques means that invasive species persist at high levels in many freshwater systems. In the UK alone, more than 120 non-native species have become established in freshwater systems, accounting for 24% of fish, 12%of plant, 54% of amphibian, and 88% of decapod species richness.

The American signal crayfish - an important freshwater invader in the UK.

In-stream Infrastructure and Invasive Species

Globally, river systems have been extensively modified through the construction of in-stream infrastructure such as dams, weirs, and culverts. The impacts of these structures are well documented, but their interaction with invasive species is largely underappreciated. Some studies have demonstrated that the reservoirs created upstream of in-stream infrastructure are much more vulnerable to invasion, and frequently support higher densities of invasive species. Conversely, a growing body of literature suggests that these structures may act as barriers to the spread of invasive species, and may be an invaluable management technique.

The aim of this PhD is to explore the impacts of in-stream infrastructure on invasive species at all stages of the invasion process, with a particular focus on three key questions:

1: How do barriers affect the introduction, establishment, and spread of invasive species?

2: How effective are barriers as a management technique at a landscape scale?

3: What are the individual/population level characters that can predict barrier passage by invasive species?


An example of anthropogenic in-stream infrastructure in a UK river.

Other Research Projects

University of Southampton - Identifying the effects of barotrauma on a neotropical fish (below left)

University of Bristol - Determining the effects of metal nanoparticles on benthic algae (below middle)

University of Bristol - Determining the effectiveness of a novel method of camouflage generation (below right)


Barotrauma chamber being used to assess the impacts of rapid decompression on a neotropical fish species.


A small camouflaged target used to assess the effectiveness of a novel method of camouflage generation.

Experimental flumes being used to test the impacts of metal nanoparticles on benthic algae.