Home » Blog posts » Dispatches: Ancient DNA reveals ecological history

Tsleil-Waututh canoe travel in Indian Arm at DiRr-6, a massive outcrop of intrusive granodioritic rock marked with a single painting, 2014. Most rock paintings were meant to be seen in this context. Photo by Jesse Morin
Tsleil-Waututh canoe travel in Indian Arm at DiRr-6, a massive outcrop of intrusive granodioritic rock marked with a single painting, 2014. Most rock paintings were meant to be seen in this context. Photo by Jesse Morin

Dispatches: Ancient DNA reveals ecological history


Occasionally, this space includes reports and essays from guest writers on the subject of Puget Sound ecosystem recovery. Social scientist Whitney Fleming has this dispatch on new findings that are being revealed by ancient sources. Archaeologists are looking at ancient DNA combined with oral histories to determine ecological conditions from the past. 

By Whitney Fleming

People have inhabited the waters around the Pacific Northwest for thousands of years. It is only in recently that humans have destroyed ecosystems in the Salish Sea to the point where they need fixing.

Scientists and policy makers are trying to figure out how to save these systems that have been broken by decades of overuse and unsustainable practice. It is not a simple problem because cumulative effects from human actions damage ecosystems over time. These actions are not limited to the present. They also include future impacts and the things that humans have done in the past.

Ecological restoration involves returning nature to a healthy state — to how it was before — but how do we know what that state is? How do we know what we are trying to restore?

Looking at a small inlet, just to the north of Puget Sound near Vancouver, Canada, an interesting story of ecological history has unfolded. As archeologist Dr. Jesse Morin explains, Burrard Inlet records show that as far back as 1913, shellfish beds were inaccessible and devastated because of oil spills from a nearby refinery.

It is also true that herring, a keystone species in the area, were completely gone by 1898.

In many cases, Traditional Use Studies (TUS) are used to determine pre-European arrival conditions. These are studies that use the knowledge of native peoples to determine what resources they used, and what species were present. These studies do exist in Burrard Inlet from the Tsleil-Waututh harvesting practices, but the histories are from the mid 1900s.

“Forage fish are as important as salmon, and they don’t exists here anymore.” Dr. Morin says. By the mid 1900s, “Most these species were gone, some of them were too toxic to eat, and most of the land was already taken up by industry.”

Even if oral histories and TUS studies cannot provide the information needed for restoration, the historic lives of Tsleil-Waututh people can still give the answer.

Just like humans today, the native peoples of the region used to throw things away. While plant based material has long biodegraded, some things are left behind. Remarkably well preserved in this region, the garbage of the Tsleil-Waututh remains, leaving a 3,000-year trail of history. As Dr. Morin so lovingly described his line of work “Archaeology is the science of garbage piles.”

These left-behind garbage piles create stratified layers that scientist can radiocarbon date to get a timeline of history. Importantly, this garbage contains the remains of what people ate before the ecosystem was impacted by the arrival of European settlers.

The remains of animals, including fish, birds, shellfish, and mammals are present in these important archeological finds. One pile from Burrard Inlet contained the remains of over 70 species.

These relics are the key to uncovering what the environment looked like before the European arrival. Dr. Morin is able to examine the DNA present in these samples and determine the exact species that were present during those times. Using this ancient DNA of salmonids and herring, his work unfolds a clearer picture of what the ecosystem of Burrard Inlet looked like back in time.

Through this technique that combines social science and ecology, researchers hope the past leaves a door open for restoration in the future.

Whitney Fleming is pursuing a PhD in Integrating Ecosystem Services and Human Wellbeing at Oregon State University. This article was produced as part of the 2018 Salish Sea Ecosystem Conference student writers project. Funding and support was provided by the Environmental Protection Agency’s National Estuary Program and the Salish Sea Ecosystem Conference.