Three years of spring sampling trips resulted in thousands upon thousands of data samples.
Back at the University of Alaska Fairbanks, the scientists resettle into their lab. Now with all their samples in front of them, they work to draw meaning from these snippets of information. It's like putting together a puzzle, but this one will take years to finish!
Dr. Rolf Gradinger quickly discovered that there was a huge amount of ice algae production happening in the Bering Sea, even more than the team had hypothesized! Dr. Gradinger found that as much as 50% of all the algae growing in the Bering Sea in spring was growing with the sea ice.
Armed with this knowledge, Dr. Bluhm and Dr. Iken set to work decoding the food web. First, they wanted to figure out which animals in the Bering Sea feed directly on ice algae. The two scientists are especially interested in animals that feed directly on the sea ice, because changes in the food available for these species will impact animals all the way up the food chain.
To study the diet of these primary consumers they used a process called stable isotope analysis.
VIDEO: BUILDING A FOODWEB USING STABLE ISOTOPES
Learn about how researchers can piece together the marine food web by looking at muscle tissue (1:35)
You might have heard the saying before, "you are what you eat". It turns out it's true! Certain chemicals from the foods we eat stay inside our body's tissue long after the food has been digested.
Because different foods have different chemicals in them, each type of food has its own chemical signature, it's kind of like a fingerprint. Scientists can look at these signatures inside an animals tissues to see what kinds of food the animal has been eating. The chemicals that scientists look for are called stable isotopes.
In marine ecosystems like the Bering Sea, scientists use this technique to figure out which animals are eating certain types of algae.
Imagine you're a clam. You live in the silty sediments at the bottom of the Bering Sea. In the springtime you eat 10 units of food in a day. Of these ten units, eight are of sea ice algae and two are from phytoplankton from the pelagic zone.
You go along like this, every day eating eight units of sea ice algae and two units of phytoplankton, until one day.... SCOOP... you end up in our researchers sediment grab sampler. You're hauled up to the surface and taken to the laboratory where a sample of your muscle tissue is removed and tested for stable isotope signatures.
The scientists recognize the signature of the stable isotopes from the algae you ate, so they can tell that the ice algae was an important part of your diet.
This same techique can be used on animals higher up the food chain. Even the walrus who ate the clam who ate the sea ice algae will have muscle tissue with the sea ice algae's special signature.
With the help of stable isotope analysis, the pieces begin falling into place. Dr. Bluhm and Dr. Iken are able to connect primary consumers to the ice algae they ate using their muscle tissue.
The food chain doesn't stop there! These primary consumers can be connected to secondary consumers, who can be connected to one of the ecosystem's top predators: the polar bear. Suddenly, scientists are able to show that sea ice isn't just important to a few species; it connects animals throughout the food web!
Navigate through the food web below to see what scientists have learned about how arctic organisms are interconnected:
The evidence collected as part of this project clearly supports the team's hypothesis that sea ice is an important food source for pelagic and benthic Bering Sea communities during the springtime.
The question now is: What will it mean for marine life as sea ice conditions in the Bering Sea continue to change?
Scientists aren't sure yet, but they know that research projects like this one are important because they will provide baseline information which will help the science community quantify ecosystem changes over time.
WHO IS STUDYING SEA ICE?
ISOTOPES (n)- different forms of the same chemical
INTERCONNECTED (adj)- connected with each other
CLIMATE (n)- the general weather conditions in an area over a long period of time
BASELINE (n)- a starting value that is used for comparison to future values