A Big Role for Tiny Organisms


In nature, the very small can have a very big ecological role to play. In this article, we look at the effect that climate change has on lichen and plankton. Lichen and plankton may seem insignificant but they are vital components of the food web, and serve as examples of how climate change can be devastating to species in the Arctic ecosystem.

Lichen on the Land


Lichens are a unique and fascinating combination of fungus and another organism that goes through photosynthesis (called photobionts), usually algae or cyanobacteria. These organisms work together to form what is known as a symbiotic relationship, which is where both parties benefit from working together. In this case, the photobiont produces sugars through photosynthesis (just like leaves on trees!), which provides the fungus with a food source, and the fungus produces nutrients that benefit the photobiont. Thanks to this relationship, lichen can be found in a wide variety of habitats, including on the trunks of trees or leaves in moist forests, on fallen logs, bare rocks, or on soil. Lichen also thrives in some of the most extreme conditions, including hot, dry deserts and the frigid cold Arctic tundra.

lichen under snow

During the winter, food is often scarce on the Arctic tundra. The presence of hardy organisms like lichen can mean the difference between surviving and starving for large mammals like caribou. Being the primary food source for large migratory caribou herds in North America, lichen can become depleted quickly. As long as the conditions are correct, the lichen can grow back and provide caribou with food for another winter. Unfortunately, when climate change is added to the mix, it’s a different story.

Climate change is causing the Arctic to warm up and dry out, making it more difficult for Tundra lichen to grow back for the winter. This critical winter food source for large migratory caribou is disappearing, which could lead to population declines in the future. Who would have thought that climate change could impact large animals like caribou by hurting the tiny lichen that caribou eat?

Plankton in the Water

Arctic OceanIn 1989, sea level pressure in the Arctic dropped sharply. When sea level pressure changes like this, it can cause a change in the flow of air and water. Warmer, more salty water from the North Atlantic Ocean started flowing into the Arctic Ocean. This wouldn’t have been too bad, except that at the same time there were also significant changes to the climate. Permafrost, snow and ice were all melting at a faster rate than before and there was an increase in precipitation. Eventually all this water made its way to the Arctic Ocean, causing an even more dramatic change in the water flow. The warm salty water was coming up from the south, and the cold, less salty water was pushed down from the north.

These major changes to the environment meant that species living in the Arctic and Atlantic Oceans have had to adapt or move if they want to survive. Take plankton for example. Studies have shown that plankton found in the Boreal regions have travelled south, while subtropical and temperate plankton have moved north. Not wanting to miss a meal, Boreal fish species have followed the northern plankton species south, and subtropical and temperate fish species caught up with their plankton in northern waters.

Diatoms through the microscope

This movement of plankton and fish might not seem important, but it can really impact the ecological marine food web. For species living in the Arctic that can’t easily move south, and/or need specific animal prey to satisfy their diets, the southern migration of these fish can leave them without food.

Final Thoughts

Understanding how climate change is impacting environments has taken many years of scientific study, and many more are still needed. The Arctic, like most ecological environments, is a highly resilient yet sensitive ecosystem. What seems like small changes to the food web can have major impacts for many Arctic species. As key species disappear, predators need to switch to other prey or starve.

As we continue making positive changes in our lives that reduce how we impact habitats around us and the habitats far away from us (like the Arctic), we can help offset the effects of climate change. Living in the Arctic is hard enough already, let’s give these species something less to worry about. Earth Rangers, kids just like you, and our various conservation partners keep working to help save animals. Together we ARE bringing back the wild!

Arctic Landscape


Generously Supported By

The W. Garfield Weston Foundation

A Conservation Partnership With

Churchill Northern Studies Centre

Earth Rangers is a non-profit organization that works to inspire and educate children about the environment. At EarthRangers.com kids can play games, discover amazing facts, meet animal ambassadors and fundraise to protect biodiversity.