How does climate change affect the amount of marine foods available for the people of Qikiqtarjuaq in Nunavut, Canada? No one knows for sure, but we did some research in collaboration with Inuit partners to better understand what Arctic marine food webs can look like in the future, and what this means for Inuit food security. Here is what we found!
© Daniel Small
The Arctic is one of the most sensitive regions to climate change on our planet. The temperature here have increased up to three times the global average. Recent changes in sea ice conditions have effects on the life cycles of animals and plants. For example, when the ocean warms the sea ice melts earlier in the spring. Consequently, the algae
aquatic plants. growth also starts earlier since it begins when there is enough light. This change in timing affects species that eat algae, like zooplankton, and those that feed on them and so on –that is, the whole marine food web
A food web is who eats who. It is a network of species that interact with each other through feeding relationships. .
Besides changes in the amount of algae in the ocean, some Arctic species are moving further north to places with conditions that suits them better, like lower water temperature. Other species are following their prey to new places or changing their diet, which may influence their nutrient and fat levels.
© Marianne Falardeau
We created a food web model
a mathematical equation, an algorithm, a picture, or a graph that represents a network and how its components interact with each other. representing the interactions among marine species in western Baffin Bay, Nunavut. A model of this complexity is more informative when looking at the broad effects of climate and other environmental changes on marine species compared to models with just one or two species. This is because a food web model includes the reliance of species on one another for food. For example, if a prey species becomes less/more abundant, their different predators will have less/more trouble finding food and may also become less/more abundant.
We developed this model with the community of Qikiqtarjuaq to :
1. Better understand the local food web, and how climate change affects the amount of marine foods available for the community.
2. Create scenarios of future change and analyze what these scenarios mean for animals that matter most to the community. This allowed us to think together about how Inuit could adapt their food sources in years to come.
These models were created with Ecopath with Ecosim (EwE) ecosystem modelling approach and software. Ecopath is a tool to represent the food web, while Ecosim is a tool that represents how the food web varies over time and allows us to evaluate model scenarios. To develop these models, the data used included estimates of abundance
Abundance of a species is the number of individuals of that species. of species, diet composition, growth rates and mortality rates of all species in the food web. We took this data mainly from survey reports, Western scientific literature, and expert knowledge. From abundance we calculated biomass, which we used as the quantity of food passing from prey to predator in the food web.
Narwhals
Monodon monoceros
Narwhals of the East Baffin Bay population a group of animals of the same species that live in a certain geographic area at the same time. spend the summer, from June to September, in the fjords of Baffin Island. After that, they travel for about 1,700 km to southern Baffin Bay where they stay until late March/early April. At this time, they move back north to the Baffin fjords. Narwhal most common preys are Arctic cod and Greenland halibut.
Artic char
Slavelinus alpinus
Arctic char is a fish that spends part of their life in freshwater and another in the ocean. In the Baffin region, this fish spends the winter in rivers and lakes in Baffin Island, where they reproduce. As adults, they migrate through the fjords and into Baffin Bay coastal areas when the rivers are ice free. They normally spend the summers feeding on zooplankton in marine waters along the coast and move back into freshwater during the fall.
Ringed seal
Pusa hispida
This seal is completely adapted to ice-covered waters and does not travel in the winter, staying in Baffin Bay year-round. In the summer and fall, some seals remain close to their breeding sites while others disperse along the coastline. Some spend time in the open water far from the coast, and others move north to the ice edge. They eat mainly Arctic cod and zooplankton.
Polar Bear
Ursus maritimus
Polar bears can move quite a lot across Baffin Bay and up to the North Water Polynya. In the winter, bears can be found on the sea ice in the bay looking for their favorite prey – the ringed seal. In summer, the bears use either eastern Baffin Island or the Melville Bay area as a summer retreat. Besides ringed seal, bears also eat other seals that spend the summer in the area.
Note that model scenarios are not a prediction of the future. Instead, model scenarios help understand how our actions can lead to different possible futures. With this information we can better prepare to adapt to climate change.
IN CONSTRUCTION
Species – in biology, a species includes animals, plants, bacteria or fungi that share common characteristics and can reproduce together. For example, dogs belong to the species Canis familiaris.
Population – a group of animals of the same species that live in a certain geographic area at the same time.
Network – a group of interconnected people, other species, or things. For example, Facebook is a network that connects people all over the world.
Food web – A food web is who eats who. It is a network of species that interact with each other through feeding relationships.
Model – a mathematical equation, an algorithm, a picture, or a graph that represents a network and how its components interact with each other.
Model scenario – a possible new arrangement of a network (represented in a model).
Food security – a food secure community is a community that has access to enough, nutritional, and safe (not contaminated) food.
Abundance – of a species is the number of individuals of that species.
Biomass – is the number of individuals of a species multiplied by the average weight of individuals of that species. For example, we use biomass of a fish population to determine how much of that fish is available for fishing.
Algae – aquatic plants.
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