ACRD's Dr. Caroline Chénard and Scott MacQuarrie preparing a conductivity, temperature, and depth sensor for sea deployment. Photo by Jörg Behnke.
Seawater may seem clear, but a single drop is alive with countless microscopic organisms—tiny powerhouses quietly supporting Canada's fight against climate change.
Phytoplankton turn sunlight into energy, feed nearly every creature in the ocean and help control the air we breathe. But as they adapt to the warming ocean, these microorganisms might be the first responder to changes that ripple through the entire marine food web, including the fish we eat.
To get ahead of these changes, researchers from the National Research Council of Canada (NRC) are working with Dalhousie University through the NRC's Ocean program to uncover what's happening beneath the surface. The team aims to support a sustainable future for coastal communities that depend on the ocean for their livelihoods by exploring how Canada's ocean ecosystems can stay healthy and resilient as the climate warms.
Reading the ocean's genetic fingerprints
Working with different microalgae strain samples in the lab.
At our Aquatic and Crop Resource Development Research Centre, Research Officer Caroline Chénard is the lead on the project that uses environmental DNA, or eDNA, from phytoplankton to track how extreme temperature events and marine heat waves are reshaping life in the Northwest Atlantic.
As water passes through an extra-fine filter, phytoplankton are collected and their DNA can be extracted. By sequencing that DNA, researchers can identify the hundreds or even thousands of phytoplankton species living in a single drop of ocean water, giving us a genetic fingerprint of our waters.
Phytoplankton react almost instantly to temperature shifts, giving scientists some of the first clues that the ocean is changing. "Various species of phytoplankton can adapt differently to changing water temperatures," says Dr. Chénard. "And because phytoplankton are literally at the bottom of the marine food chain, we want to understand how that shift could affect the rest of the ocean."
Different microalgae strain samples in the lab.
In a research paper titled Organellar Genomes of Three Globally Important Nanoplanktonic Diatoms Refine Their Taxon-Specific Distribution and Succession Patterns in the Northwest Atlantic, published with collaborators from Dalhousie University, the team identified distinct seasonal patterns, mostly influenced by temperature, for 3 closely related species. One of those species dominates in colder waters (−1°C to 5°C) whereas the others prevail at higher temperatures (above 9°C).
Tracking these biological changes helps researchers predict how a warming ocean will affect the entire marine food web.
It's a powerful new way to see how the ocean responds to climate change in real time.
"I'm proud to be collaborating with the ACRD team at the NRC," says Rebecca Stevens-Green, PhD candidate in the Department of Biology at Dalhousie University. "Together, we're using a rapid DNA‑sequencing method (Nanopore) to assemble chloroplast genomes and identify genetic 'barcodes' that let us track these species across the Northwest Atlantic. As ocean conditions warm, smaller plankton like the ones we studied may become more common, and these 'barcodes' will help us monitor their abundance in the future."
Microscopy image of the Minidiscus spinulatus (diatom) culture isolated from the Bedford Basin taken with the NRC's inverted microscope (the Leica DM IL LED).
Protecting Canada's blue future
For Dr. Chénard, this work is both scientific and deeply personal.
"I love the ocean. I grew up close to the sea and I always wanted to study the ocean," she says. "It's so important that we know more about what lives in the ocean, especially the microscopic life, which probably have the biggest impact on our own lives."
By monitoring how climate change is affecting the smallest of sea organisms, NRC researchers are helping protect vibrant marine ecosystems and a healthy ocean. Their work supports the sustainable use of Canada's ocean resources and strengthens the country's blue economy.