Marine Snow: Lifeline to the Deep
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March 6, 2025

Marine Snow: Lifeline to the Deep

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As record breaking snowstorms sweep through Canada, a different kind of snowfall is happening beneath the waves—marine snow. Unlike the frosty flakes outside your window, this mesmerizing drift of organic particles plays a vital role in sustaining deep-sea life and fighting climate change. 

WHAT IS MARINE SNOW?

Marine snow consists of tiny flakes of biological material—dead plankton, waste, and organic matter—that sink to the bottom of the ocean where it sustains life. It’s a magical biogeochemical phenomenon that begins at the top layers of the ocean and ends with a slow and steady drift to the seafloor. As it sinks to the depths of the sea, this underwater snowfall grows collecting other floating debris, including fecal pellets (a.k.a poop), decaying plants, dead animals, and other organic debris. 

HOW IS MARINE SNOW FORMED?

Marine snow is formed by key oceanic processes that begin in sunlight at the surface of the water, fueled by photosynthetic phytoplankton. With each passing wave the sunlight grows microscopic plankton at the ocean surface and when they die they leave behind traces of their existence, falling to the seafloor. 

Unlike the snow that melts on land, ocean snowflakes grow as they fall. As the organic debris from the ocean surface sinks, flakes clump together with other materials, increasing their size and speed towards the deep sea. Marine snow carries carbon, nutrients, and other byproducts of photosynthesis to the seafloor. It’s a vital mechanism driving deep-sea food webs and carbon storage, making marine snow one of the ocean’s essential processes.

WHAT ARE THE BENEFITS OF MARINE SNOW?

Marine snow is the foundation of food for animals that live deep in the ocean. Without it, life in the depths would be far scarcer. Sunlight never reaches the ocean’s deep waters, but marine snow does. It drifts down like a slow-motion blizzard, sustaining creatures that would otherwise struggle to survive. 

From filter-feeding jellies to tiny krill, and vital habitat-forming ecosystems such as corals and sponges, life in the deep sea relies on marine snow for food. Animals that form the base of the ocean food web, like sea lilies, polychaete worms and brittle stars, feast on these falling particles, and larger animals, like halibut, rockfish and sharks, in turn prey on them. Marine snow is a deep-sea powerhouse of nutrients, but its importance goes beyond feeding ocean life. 

Marine snow falling next to deep sea marine creature swimming.
Marine life captured in the deep sea during the 2018 expedition in the Northeast Pacific Seamounts

HOW DOES MARINE SNOW HELP CLIMATE CHANGE?

Marine snow also plays a role in fighting climate change, capturing and storing carbon deep in the ocean. As organic matter sinks, it carries carbon with it, effectively removing it from the atmosphere. This process helps trap CO2 in the deep sea and keep it out of the atmosphere, contributing to the mitigation of climate change. Marine snow is a key component of the biological carbon pump, ensuring that carbon is stored deep underwater for centuries, helping maintain a balance in the Earth’s carbon cycle. 

PROTECTING MARINE HABITATS

Marine snow may be tiny, but its impact is enormous. Protecting the oceans in Canada means helping all life within them—including the quiet snowfall that keeps the deep-sea thriving. Oceana Canada works to protect the ocean and over the years has already had big wins. 

Advocating for increased protection in Marine Protected Areas (MPA) and permanently protecting a biodiversity hotspot, seamounts, in British Columbia. Protecting this area was a collaboration between Coastal First Nations alongside science-based campaigning and research including data from a 2018 expedition in partnership with Oceana Canada.

HELP US PROTECT MARINE HABITATS

Oceana Canada is continuing to fight for the oceans. We are protecting vital ecosystems from threats such as bottom-contact fishing gear, deep-sea mining as well as oil and gas. You can be part of this change for the oceans. To learn more about protecting marine habitat and how to join in support for the oceans, become a Wavemaker. You’ll get the latest ocean news and ways to take action. >>>