FERG Members

Academic Staff

Angus McIntosh

Professor Freshwater Ecology
Deputy Head of School
Julius von Haast 226
Internal Phone: 95186

Jon Harding

Professor Freshwater Ecology
Stream Biology
Biology 333
Internal Phone: 95135

Jonathan Tonkin

Senior Lecturer and Rutherford Discovery Fellow
Population and Community Ecology
Internal Phone: 90413

Helen Warburton

Research Associate
Freshwater Ecology
Julius von Haast Rm 331
Internal Phone: 95212

Issie Barrett

Senior Tutor
Waterways Centre for Freshwater Management
Internal Phone: 91368

Postdoctoral Fellows

Technical Staff

Linda Morris

Technical Officer
Technical Teaching Coordinator
Freshwater Ecology and Cell Biology
Julius von Haast 318
Internal Phone: 95196

Research Staff

Chris Meijer
Research Assistant

PhD Students

Channell Thoms

Channell Thoms
There are a number of research projects that have focused on the physical restoration of waterways and habitats, however, there is little known about reintroducing native species back into rehabilitated environments. Reseeding of native species that could potentially assist with stream rehabilitation is the most logical “next step” in stream restoration. Channell’s research focuses on using kākahi, freshwater mussels (Echyridella sp.) to act as a biological tool to assist with waterway restoration efforts. Kākahi are ideal candidates as they perform a number of ecologically important functions in waterways. These functions include acting as bio-engineers which can physically shape environmental habitats; bio-indicators, which can assist with assessment of water quality; and filter feeders, which may help with removal of particulates and contaminants.

Research interests: kākahi (freshwater mussels), multi-trophic translocations of threatened endemic mahinga kai species into rehabilitated waterways.

FERG people

Ben Crichton

Ben’s research seeks to answer the elusive question of whether whitebaiting impacts the population dynamics of harvested kōkopu species and whether closing areas to whitebaiting contributes to species protection and increased production. To achieve this, Ben will monitor banded, shortjaw, and giant kōkopu populations within whitebaited and legally closed waterways on the West Coast of the South Island each month for a year. Using spotlights, the nocturnal kōkopu are caught at night with hand nets and placed in buckets to be measured. Environmental variables, such as pool volume and bank cover, are also likely to affect kōkopu abundance, so these are also measured at each site. This means the effects of whitebaiting can be more precisely evaluated. His research hopes to provide insight into the sustainability of the nationally significant, but highly controversial, whitebait fishery while ensuring that kōkopu and the whitebait fishery are preserved for future generations.


Research interests: Aquatic ecology, conservation biology, fishery sustainability, freshwater fish, human-mediated impacts

FERG people

Holly Harris

Braided river systems are rare worldwide and considered to have significant natural and cultural values in New Zealand. Holly is aiming to investigate how birds, fish, mammals, and invertebrates interact and connect across terrestrial and aquatic areas in these systems. She is working on the Cass River, in Tekapo, with stable isotopes to determine what a braidplain food web in a (mostly) intact braidplain system looks like. This work aims to enhance our understanding of rivers as highly connected systems that don’t just span an area covered by water in one point in time. It also aims to aid management decisions by identifying trophic connections that could occur on multiple scales and be impacted by changes that cascade into other areas of the system.

Research interests: Braided rivers, food webs, cross-system subsidies, trophic connections

FERG PhD student

Gabrielle Koerich

Species distributions are closely linked with the environment, and as such, alterations driven by climate change are expected to affect species’ ranges. Determining how the distribution of species will change in space and time is central to guiding decision-making of conservation actions. Gabrielle is exploring how a warming climate will affect the distribution of terrestrial Antarctic species, as part of the Antarctic Science Platform. First, she is aiming to understand what are the main ecological processes driving biogeographical patterns in Antarctica, to then inform hybrid distribution models to forecast species geographical ranges under novel environmental states.


Research interests: species distributions, climate change biology, niche theory, conservation biology

MSc Students

FERG MSc student

Rory Lennox

We are already seeing larger, more frequent floods in NZ because of climate change, but we don’t fully know how these floods will affect our native species alongside other pressures. My project aims to explore the relationship between native non-migratory galaxiids, introduced trout and flood disturbance. Using mark and recapture techniques across Arthur’s pass, I am investigating how native non-migratory galaxiid populations are recovering from the May/June 2021 Canterbury floods while in the presence of introduced trout. By doing so, this project can better inform management of our native fish against threats of introduced species and climate change, to ultimately help preserve our native fish in future with climate change predicted to worsen.


Research interests: Freshwater fish, predator-prey interactions, invasions and non-native species, conservation biology, flow-related disturbances

FERG MSc student

Elysia Harcombe

Droughts are forecast to become increasingly frequent on the east coast of New Zealand’s South Island due to climatic change and increasing water abstraction. However, most knowledge around the effects of drying on aquatic fauna is for charismatic vertebrates such as fish. Elysia’s research hopes to address this by improving knowledge on the effects of droughts on stream invertebrates. Her research will describe how and why aquatic insect communities change as streams start to dry. This will be achieved by studying how invertebrate behaviour (such as drift and emergence) and invertebrate interactions (such as predation and competition) change along a spatial gradient of drying. Elysia will be conducting surveys across six drying streams and using experimental mesocosms which manipulate the interactions between aquatic invertebrates.


Research interests: Drying streams, macroinvertebrates, community structuring processes, aquatic invertebrate behaviour

FERG people

Brittany Earl

The brown tree frog, Litoria ewingii, has been present in the South Island of New Zealand for almost 150 years after being introduced from Australia. There have been many observations of remote ponds and tarns teeming with their tadpoles, but little to no investigation on their ecological impact. Brittany’s research aims to uncover the effects of their presence on native pond communities. Using mesocosm experiments she hopes to determine which organisms they directly affect, and which elements of pond ecosystems are affected indirectly. She also is conducting a survey over the Canterbury high country to uncover growth rates, distribution, and habitat preference. This synthesis of information on their distribution, life history, and effect on native organisms will be vital to determine if L. ewingii is a threat to native flora and fauna.


Research interests: Invasion & NZ conservation, animal behaviour, pond ecology, mesocosm experiments

FERG people

Olivia Hore

Olivia is assessing the effects trout influence on native non-migratory galaxiids (NMG) under natural and reduced flow conditions. This research is supervised by Professor Angus McIntosh (UC), Dr Jonathan Tonkin (UC), and Dr Nixie Boddy (DoC), and funded by DoC. Over the 2020-2021 summer, she has been using electric fishing, and mark-recapture techniques to assess NMG population abundances, growth rate, and size distributions in streams with and without trout, which exhibit a drying flow regime. The overarching aims of this research is to determine how NMG and non-native trout interact between areas of low-flow and permanently flowing sections of stream, and to investigate the influence trout exert on important aspects of NMG populations under these varying flow conditions to inform conservation actions for NMG.


Research interests: Freshwater fish, predator-prey interactions, invasions and non-native species, conservation biology, flow-related disturbances

BSc (hons) Students

FERG people

Ciara Espiner

Macroinvertebrates play a crucial role in the functioning of freshwater ecosystems across New Zealand. Mayflies, in particular, are vital to aquatic environments as they form the trophic basis of food-web production. However, as the climate continues to warm and the rate of both river flooding and drying intensifies, these aquatic invertebrates may face a mismatch between their evolved life history traits and the changing environment. Focusing on Deleatidium mayflies, Ciara’s research seeks to investigate the plasticity of mayfly life history traits, like developmental rate and size at emergence, in response to stressful conditions such as drying and flooding. Ciara aims to uncover patterns and triggers behind the plasticity of mayfly life history traits using multiple field surveys and a mesocosm tank experiment.

Research interests: Freshwater and marine ecosystems, conservation, climate change, animal behaviour, animal physiology, human-induced evolution

FERG people

Imogen Eglesfield

Currently, there is a mismatch between environmental restoration and the return of a diverse instream community, with the less-desirable fauna, such as snails and worms, becoming more abundant post-restoration and potentially excluding other invertebrates, such as mayflies and caddisflies. Imogen’s research focuses on how the success of colonisation is affected, positively or negatively, by the species that are already established, and how this may depend upon their specific traits. Using mesocosm environments with combinations of Deleatidium mayflies, Conoesucidae caddisflies and Potamopyrgus snails, Imogen is investigating how the order of colonisation affects the likelihood of colonists successfully integrating into the community. This research will provide information about how the priority effects of established invertebrates affects the overall success of restoration, improving our ability to restore biodiversity to degraded freshwater systems.

Research interests: Biotic interactions, restoration, priority effects, species traits