Dr. Maud Ferrari, Professor in the Department of Veterinary Biomedical Sciences at the University of Saskatchewan, discusses with us her paper titled, “The fading of fear effects due to coral degradation is modulated by community composition”, the broader impact of her research, and her interest in ecology.

Me posing for an NSERC picture. I'm pretending to be looking at a fish tank in my lab in Canada. Photo courtesy of NSERC.
Me posing for an NSERC picture. I’m pretending to be looking at a fish tank in my lab in Canada. Photo courtesy of NSERC.

About the paper

What’s your paper about?

A predatory dottyback (background) and a damselfish (closer up). Photo courtesy of Chris Mirbach
A predatory dottyback (background) and a damselfish (closer up). Photo courtesy of Chris Mirbach

Coral reefs throughout the world have become degraded as a result of increased ocean temperature and the frequency of destructive storms. Once degraded, the diversity of reef dwelling organisms dramatically decreases. This decrease in diversity has been partially linked to changes in the ‘smells’ of the dying reef which leads to a decrease in the number of fish immigrating to those reefs (recruitment failure) due to the lack of chemical attractants, and an increase in the number of fish dying due to predation. This study aimed to better understand the cause of increased predation in degraded coral, and further, to find mechanisms that would increase the ability of damselfish to survive predation in dead coral environments.

What is the background behind your paper?

Aquatic prey from all taxa are able to detect the smell of injured conspecifics (members of the same species) and closely related or known members of other species. Termed “alarm cues”, these cues indicate that a predator has successfully captured or injured one of their kind and thus, these cues are a trustworthy indicator of predation risk. When prey detect alarm cues, they immediately engage in antipredator behaviours which can include fleeing, seeking shelter or becoming cryptic to avoid detection. Prey can also learn to recognize novel odours as threats when they co-occur with alarm cues.

Within degraded reefs, however, some fishes (let’s call them alarm cue “non-responders”) are not able to detect alarm cues and suffer increased mortality. However, other species, even closely-relate ones, appear to remain unaffected by the degraded coral (let’s call them alarm cue “responders”). We hypothesized that the presence of responders in the vicinity could help non-responders identify novel predation threats by ‘sharing’ their alarm cues.

I'm inserting an elastomer tag in a juvenile damselfish, so they can be identified in the field once released. Photo courtesy of Doug Chivers.
I’m inserting an elastomer tag in a juvenile damselfish, so they can be identified in the field once released. Photo courtesy of Doug Chivers.

To explore this idea, we created large reef pools, filled with water from either live or dead coral environments, and added a novel predator (a dottyback, Pseudochromis fuscus), along with 20 predator-naïve juvenile damselfish of two species, Pomacentrus chrysurus (responders) and P. moluccensis (non-responders). We had some pools where the predator interacted with 20 responders only, or 20 non-responders only, or 20 fish of varying ratios of responders to non-responders. Downstream, we set a container with predator-naïve non-responders. These fish served as our focal individuals: they could not interact with the predator and were only able to learn information about the predator based on chemical information released from the upstream community. They had to rely on ‘upstream’ information to learn about the threat.

After 24 h, we tested the downstream non-responders to see if they learned to fear the novel predator. In live coral, all fish had learned to recognize the novel predator as a threat. This showed that alarm cues worked as expected and served as distant indicators of risk for nearby prey. In dead coral, however, we found that in the absence of responders in the upstream pool, the downstream fish were unable to learn to recognize a novel predator as a threat. This indicates that responder species, like P. chrysurus, become the only functional source of predation-related information for nearby non-responders like P. moluccensis in degraded habitats. This is an excellent illustration of the importance of diversity in mitigating anthropogenic change.

Does this article raise any new research questions?

Now that we know that some species can benefit from and survive better in the presence of other species, the question that remains is: will these ‘non-responders’ species select to settle nearby ‘responders’?

About the research

What is the broader impact of your paper?

Beyond our understanding of the role of predation in reef environments, our study provides a tangible example of the importance of maintaining and protecting biodiversity, especially when species are challenged by a rapidly changing environment.

Why is it important?

The debate on the importance and necessity of diversity has long been debated in the scientific and lay community. Our study provides direct evidence that two closely related species with similar ecological niches can play very different, yet intertwined roles in a changing environment.

About the Author

How did you get involved in ecology?

Me doing field work in Canada, measuring dissolved oxygen levels in the water. Photo courtesy of Katherine Fedoroff.
Me doing field work in Canada, measuring dissolved oxygen levels in the water. Photo courtesy of Katherine Fedoroff.

I have always been passionate about predation. As an undergrad, I had the opportunity to work on a project looking at the role of acid rain in interfering with the way fish avoid predators. I was hooked!

What are you currently working on?

My lab is currently working on several initiatives. We are exploring the presence and impact of microplastics in freshwater and marine environments, the role of noise pollution in aquatic environments, interactions between invasive species and species at risk, in addition to several projects examining the role of predation and fear effects in the life of prey.

What’s your current position?

I am currently a professor at the University of Saskatchewan.

What do you do in your spare time?

Most of my spare time is devoted to raising my two young children, who are as passionate about nature as I am. In addition, I enjoy travelling, learning new things, and mentoring the passion of young scientists, especially women.

One piece of advice for someone in your field…

I think it’s a piece of advice for anyone doing anything new and challenging. Don’t fear your failures – embrace them. Study them, learn from them and become better. Failures and feedbacks (from the right people) are your only worthy source of improvement.

Read the paper here!