Interview with Marie-Pier Hébert The 2023 Raymond L. Lindeman Award Recipient

Each year, ASLO recognizes exceptional work in the aquatic sciences, nominated by the membership, with society awards. In recent years, the ASLO Communications Office has conducted an interview with each awardee to hear more about their work and careers in their own words. Recently, we caught up with Dr. Marie-Pier Hébert, the winner of the 2023 Raymond L. Lindeman Award for her article, “Warming winters in lakes: Later ice onset promotes consumer overwintering and shapes springtime planktonic food webs.”

MPH: Working in winter can be very fun! But it does come with various challenges, some being more unexpected than others. For this in situ experiment, our core challenge was to develop effective procedures to manipulate the timing of ice cover onset. The idea may sound simple, but doing so in a realistic manner was not trivial, not to mention that our treatment was by nature vulnerable to weather conditions. This is the reason why it took us not one but three winters to run this experiment fully.

In short, our goal was to postpone the natural formation of lake ice cover within enclosures (or mesocosms), without manipulating ice in a way that could influence the volume or chemistry of water, nor plankton densities in treated sites. We did not really have any reference points to compare our methodologies with, so we had to troubleshoot by trial and error. We tested different techniques over time. One was utterly ineffective; another one (consisting of breaking the ice but leaving the broken pieces floating at the surface) even had the opposite effect of increasing the ice layer and reducing light penetration over time, and the resulting look of the mesocosms had been characterized as “giant frozen mojitos” by one of my then committee members. Our final approach was simple but laborious: we manually removed freshly formed pieces of ice twice per day, transported ice pieces via snowmobile to an on-site laboratory where ice was melted at low temperatures in the dark, and then poured the ice meltwater back into respective sites. Over the years, an impressive number of people participated in the field trials, and it would have been impossible to navigate this challenge without their help and devotion.

Another obvious challenge of winter fieldwork is the cold. As enjoyable and exciting as it may be for some of us, spending long hours outside in winter can often be challenging for our bodies when we don't move much. Field days were long as we were not just sampling one site, but rather 16 mini-lake-parcels in addition to the main source lake. Even when wearing proper field gear, the winter conditions can be harsh in Québec, and the inflexibility of our treatment/sampling schedules sometimes forced us to face difficult conditions. Therefore, our sampling team had to be careful on particularly cold days, mainly for our personal safety but also for the maintenance of sampling materials and probes as those are prone to freeze or be damaged under cold-wet conditions.

Finally, one important consideration was the role of weather fluctuations in the net effects of ice manipulations. Being at the mercy of meteorological conditions likely applies to most field-based studies regardless of season, but small changes in air temperature, sunlight, and, importantly, snow accumulation can have huge effects on ice cover and under-ice light availability at this time of the year. Under-ice light attenuation was obviously rapid after snowfall, but the limited precipitation following the later ice-on dates prolonged under-ice light availability to up to 40 days. As a result, our experiment was influenced by the specific conditions of the winter during which it occurred, modulating the effect of treatment levels and allowing us to appreciate the extent of the carry-over effects of later ice onset on under-ice light availability in early winter.

MPH: Under-ice freshwater research is still limited and the historical lack of data collection in winter leaves us with many questions that remain hard to answer. A classic question that stems from experimental work is whether conclusions are transposable to a variety of natural ecosystems; this study is no exception. This work revealed links between the timing of ice onset, the prevalence of overwintering through selective fat retention, and the spring algal bloom, but several environmental factors can mediate such links. A winter with substantially different ice conditions, or a lake community with no versus multiple species capable of active overwintering could likely lead to different outcomes. Determining the environmental and organismal drivers and consequences of active overwintering requires paired winter abiotic–biotic observations over space and time. Current efforts to integrate under-ice measurements into long-term monitoring programs and initiate standardized sampling campaigns in winter will contribute to filling this gap and further answering questions in line with this work. Further incorporating physiological measures and biomarkers (e.g., isotopes, fatty acids) may also provide greater insight into how different overwintering strategies may influence energy flow within food webs under ice. One notable follow-up question will be to better evaluate how ice phenology and under-ice ecological processes may affect spring and summer dynamics. Ultimately, one of our collective goals is to gain a deeper understanding of under-ice ecology to better anticipate how lakes may change with warming winters and ice loss.

MPH: If I had to emphasize anything, it would be the importance of sticking to our core interests, because that is what keeps us going a few years into our graduate studies—at least it was the case for me. Sometimes, opportunities for collaborations, colleagues, or advisory teams may point students in various directions. I genuinely feel lucky that I've had the chance to pursue my various (and sometimes changing) interests, and in retrospect this was crucial to completing my graduate studies and publishing my dissertation work. As rational as science is, I think it's fair to say that following our heart and instinct can sometimes go a long way, especially in the context of seeing things through in graduate school.

Perhaps another aspect I would stress is the importance of acknowledging and respecting our own limits and developing expectations and work strategies in line with those. Many things can fall into this category, but one notable challenge when it comes to publishing our dissertation work is to write high-level science in a different language. Non-native English speakers are faced with an additional layer of difficulty and extra efforts are required given the role of publications in our line of work. The earlier those efforts are initiated, the easier it gets over time. When I started to write science ~10 years ago, I read books and blogs that helped with scientific writing, but very little to no guidance was offered for non-native English speakers. Perhaps more resources are available today, but I would say that exposure and practice are key. In my case I was flagging papers that I found clear and well-structured, creating banks of key words, asking for feedback from more experienced colleagues, and dissecting the edits of my native-English speaking co-advisor (who kindly devoted time throughout my MSc and PhD); all of these steps helped me overcome a steep learning curve. Acknowledging personal challenges (of any nature) early in the process helps us to find resources and coping strategies, and I believe that's key to reaching the finishing line.