• Kristina Barclay

Scientist Spotlight: Dr. Clara Mackenzie, Research Scientist (Fisheries and Oceans Canada)

Dr. Clara Mackenzie is a Research Scientist at Fisheries and Oceans Canada, and an affiliate employee of Vancouver Island University. Dr. Mackenzie gives us some insight and background on her experiences with ocean acidification research.

Dr. Clara Mackenzie conducting research in Baynes Sound, British Columbia. Photo credit: T. Green.

What is your background?

My research interests: the biology and physiology of marine invertebrate species in response to environmental stressors, and the capacity of species to adapt

My discipline/specializations: laboratory-based multi-stressor experiments for investigating climate change impacts on shellfish; selective breeding of shellfish for improved resilience to climate stressors


MSc Marine Biology (Bangor University, Wales) – My Master's thesis examined the impacts of OA on growth in adult and larval Psammechinus miliarus (green sea urchin).

PhD Marine Biology (Heriot-Watt University, Scotland) – My PhD thesis examined the impacts of hypoxia and warming on Modiolus modiolus (horse mussel) reefs including examination of oxidative stress and energetics (O2 consumption, cellular energy allocation) under warming and hypoxia conditions. I also examined the genetic connectivity and diversity of horse mussel populations as part of a preliminary investigation into population-based effects/resiliencies.

VIU Deep Bay Marine Field Station’s larval tank system. This system has been used for development of an oyster selective breeding program to examine the genetic basis for resilience to a range of environmental stressors including OA, warming and Vibrio spp.

What is your interest or background in OA?

I hadn’t heard much about OA until I returned to university to complete a MSc in Marine Biology in 2009, after a number of years of drifting and trying out other careers (e.g. high school science teacher). When it came to deciding on a thesis topic, I told my academic supervisor that I was interested in Arctic science or topics relevant to that area of the globe. He connected me with a supervisor at British Antarctic Survey who was investigating the impacts of OA to urchin species. I knew OA was an issue for both polar regions so was keen to be on board. That was really the start of my research into OA and other climate stressors. As well as finding the science of OA interesting and worthwhile, I also found myself really enjoying the technical aspects of working with an aquarium set-up, and discovered a deep curiosity and affection for marine invertebrates.

It’s been about 10 years since that first MSc OA research project. Since then, I have worked on a number of projects examining the impacts of climate stressors (OA, hypoxia, warming) on a range of invertebrate species (oysters, urchins, mussels). I worked for Bangor University as a research officer for several years on a project called SUSFISH that examined climate change impacts to various shellfish species of the Irish Sea. My specific research examined impacts of coinciding OA and warming on blue mussels, including investigation of effects to immune response, protein synthesis, shell strength, and energetics. My work on SUSFISH was an invaluable part of my research development and lead to my PhD work which examined the impacts of hypoxia and warming on horse mussel reefs, a habitat of high conservation priority in the UK and EU. I examined oxidative stress and energetic responses and began to consider the population-basis for adaptive capacity, an area of research that continues to hold a lot of interest for me. Currently, I enjoy working as a research scientist for Fisheries and Oceans Canada (in partnership with Vancouver Island University). Our work includes development of an oyster selective breeding program (in partnership with Vancouver Island University) for improved resistance to climate change stressors, and considering how hatchery practices might influence OA responses in later life stages.

I’m interested in climate stressor research because the work is varied and stimulating, and key to preserving our precious marine environments. It also has real-life relevance outside of the research sphere, with impacts extending across many areas of life and society.

The climate stressor system used by Clara during her work on the SUSFISH project at Bangor University, Wales. This system allowed for investigation of the impacts of coinciding OA and warming stressors on the physiology of Mytilus edulis (blue mussel).

Can you tell us about your past or current contributions to OA research?

My past work highlighted that impacts under multi-stressor conditions can be substantially different than additive single-stressor effects. Additionally, I found that detection and magnitude of impact can vary according to type of investigated response (e.g. genome vs cellular vs whole-body). I’m most interested in the idea that genetics and life-history can really set the stage for susceptibility to climate stressors like OA. Some of my more recent work (with T. Green at Vancouver Island University) suggests that what happens to oyster larvae in early life can alter survival in later life stages. For example, changes to the microbiome in early development may potentially play a big role in later life with regards fitness and survival under stressor conditions.

Clara’s work has involved studying the impacts of OA on oyster larvae, shown above as viewed under the microscope.

What is the one take-home about OA that you wish all Canadians knew?

OA is already happening! You hear a lot of talk about climate change impacts in the future but environmental change has/is already occurring, with huge repercussions. For instance, upwelling events on the west coast (where I’m based) regularly deliver low pH seawater to coastal environments, and these events are increasing in magnitude and duration. Oyster hatcheries on the coast have had huge mortality issues as larvae are particularly susceptible to OA. Additionally, oyster farmers in BC are having to contend with mass die-offs in the summer which we suspect are due to a lethal assembly of coinciding stressors (including OA).

Tagged oyster spat from the selective breeding program. Spat are deployed in the field to track individual performance (growth, survival) under a range of environmental conditions including OA upwelling events.
Oyster bed at Pipers Lagoon, Nanaimo, BC. Clara’s current work involves development of an oyster selective breeding program for improved resilience to climate stressors.

What excites you most about the current or future of OA research in Canada?

I moved back to Canada after 10 years of training and research in the UK to take a post-doctoral research position with Fisheries and Oceans Canada in Nanaimo, British Columbia. It has been particularly intriguing for me to enter into research in a location where OA is already occurring. I couldn’t believe some of the carbonate chemistry values I was measuring in “ambient” water samples. When an idea moves from “in the future” to “now”, it’s a big motivation to start finding solutions.

Baynes Sound off eastern Vancouver Island, one of British Columbia’s primary shellfish farming areas. Summer mortality, thought to be due in part to coinciding environmental stressors (e.g. OA, warming, Vibrio spp.), has caused huge declines in oyster production in recent years.

I’m currently working with some excellent shellfish researchers including Chris Pearce (Research Scientist, DFO) and Tim Green (Canada Research Chair in Shellfish Health and Genomics, Vancouver Island University) as well as a great team of biologists, technicians and students at Pacific Biological Station and VIU’s Deep Bay Marine Field Station. There is a wide range of expertise across the research team which leads to interesting and innovative project ideas. I’m greatly enjoying the enthusiasm, open-mindedness and intelligence brought to projects, and of course the thrill of discovering something new.

VIU Deep Bay Marine Field Station raft with suspended nets/trays of oysters used in field deployment trials
VIU Centre for Shellfish Research workboat, the Atrevida, used for a range of research work including oyster deployment/collection, water sampling to determine the carbonate chemistry of local waters, and collection of low-pH seawater for OA experimental work.
Winter boatwork in Baynes Sound off Vancouver Island.

Anything else you’d like to say?

I came to this area of research a little later in life and after considerable soul-searching. It took a lot of hard work, determination and definitely some luck to find a good fit for me but I would encourage anyone who isn’t quite sure what they want to do, to keep searching until that fit is made. It’s definitely been worth it for me - working on an global (and local) issue like OA is interesting and exciting and without sounding trite, brings meaning to my life. I would be happy to hear from anyone who is interested, regardless of your background or training, if only to have a chat about ways to get involved.

Clara with tagged oysters ready for field deployment. Individual oysters from ~40 families of oysters have been deployed in the field for tracking of performance to inform a selective breeding program for improved resilience to summer mortality stressors (e.g. OA, warming, Vibrio spp.)

To learn more about Clara’s research, please visit her ORCID Profile.

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