Not your average cruise: collecting phytoplankton for ocean health

- Halifax, Nova Scotia

CTD-rosette cast for water sampling on board of the RV Coriolis II during the research cruise in Gulf of St. Lawrence in June 2022. Photo by Jörg Behnke.

After a 2-week cruise in the Gulf of St. Lawrence, the 50-metre Canadian research vessel RV Coriolis II docked at Rimouski, Quebec in late June 2022. But this was no luxury cruise. More than a dozen scientists who had been working around the clock collecting hundreds of water samples for chemistry analysis and phytoplankton isolation disembarked with their catch. Two of the cruise participants, Drs. Caroline Chénard and Jörg Behnke from the National Research Council of Canada (NRC), immediately drove the phytoplankton samples to their lab at the Aquatic and Crop Resource Development Research Centre in Halifax, Nova Scotia for closer examination and testing.

Phytoplankton: a life source

Phytoplankton help to produce and sustain life on Earth by providing food for sea organisms that are eaten by other ocean life and eventually humans. Like trees on terra firma, they produce their energy via photosynthesis. During the course of that, they create more than 50% of the oxygen we breathe.

With increasing greenhouse gas emissions, oceans are experiencing a rise in seawater temperature and a constant decrease in pH (acidification). Those changes may have a negative effect on some phytoplankton communities and their role in feeding vital species.

Fortunately, phytoplankton can also be used to monitor ocean health and the impacts of nature and humans on marine life. Human activities can lead to oil spills, pollution or runoff from urban centres or farms. Other human impacts as well as natural phenomena influence temperature, salinity or ocean acidification.

Because they change constantly and adapt rapidly to their environment, some phytoplankton species can act like weather forecasters to predict threats to ocean health. Studying a range of samples will help researchers determine which species are the best harbingers of oceanic health, and how to leverage their responses for the good of the ocean.

Collection of water samples for phytoplankton genomics during the research cruise in Gulf of St. Lawrence in June 2022. Photo by Jörg Behnke.

"To better understand the reaction of these native phytoplankton communities to environmental stressors and climate change, we must access and study samples that represent the biodiversity and conditions of Canadian waters," says Dr. Stephen O'Leary, Team Lead, Algal Genomics and Synthetic Biology, NRC. "This advanced research yields new levels of information that help us mitigate the dangers to the marine environment, such as knowing when to reduce industrial activity in an affected area."

But the NRC cannot do this alone: the Aquatic and Crop Resource Development Research Centre team is working with a close community of scientists and partner organizations to share equipment and expertise.

Smooth sailing with collaborators

The NRC has partnered with the Department of Fisheries and Oceans (DFO), the Marine Environmental Observation, Prediction and Response Network (MEOPAR) and several universities to collect phytoplankton samples from the ocean on a number of cruises in Canadian waters. Since the NRC does not have oceanographic research vessels and sampling equipment of its own, partnering with DFO and other Canadian organizations, such as MEOPAR, to access such resources is a critical element to success.

The first such cruise on the CCGS Hudson was completed in August 2021 between Dartmouth, Nova Scotia and Placentia Bay, Newfoundland and Labrador. The second cruise on the RV Coriolis II in June 2022 was in the Gulf of St. Lawrence. Another cruise in the Gulf of St. Lawrence this fall will be on the Atlantic Condor using Modular Ocean Research Infrastructure.

The diverse researchers on board the June 2022 cruise were from the NRC, Dalhousie University in Halifax, the University of British Columbia, the University of Quebec in Rimouski and the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany.

According to Dr. Caroline Chénard, Research Officer, Aquatic and Crop Resource Development Research Centre, this extensive partnership brought a network of research excellence to the project. "Working with such leaders from diverse disciplines offers a broader perspective on factors that affect ocean health – and expedites our ability to devise remedies," she says, pointing out that the NRC brings expertise in phytoplankton and genomics characterization to the table. Other organizations contribute ocean chemists and environmental scientists who measure parameters such as temperature, nutrients and oxygen concentrations.

These expeditions are also great opportunities to add new phytoplankton species to the NRC's culture collection. This will extend the phytoplankton library, which contains valuable resources for NRC researchers and collaborators to use in future research activities and technology development.

Research in Canada's 3 expansive oceans has global significance. "What we learn here is very important to us, but it also needs to be compared with what's going on in other parts of the world because the oceans are all connected," adds Dr. Chénard.

From test tubes to tools

To take forecasting to the next level, researchers have begun to develop biosensors that can be deployed with more traditional sensors for temperature, water chemistry and light to provide real-time information about changes in the ocean's biological community. The fast feedback they provide can help industry and regulators foresee events that may be damaging to ocean health and react in good time.

For example, large-scale fishing and resource extraction industries will be able to track trends in ocean chemistry and productivity, and regulators can monitor changes that industries near the shores have on the ocean environment. This involves checking for issues such as contamination, temperature changes and nutrient status.

"Being able to forecast ocean health is important to communities around the world," says Dr. O'Leary. "We must be stewards of the ocean waters around Canada, while staying on top of the best science practices available. We must also find ways to contribute with new technologies and information to drive even better scientific practices worldwide."

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