A couple of months ago, people wandering in the ruins of the Sutro Baths on San Francisco's Ocean Beach noticed something odd. An otter was swimming around in what was, 120 years ago, a giant luxury pool at the water's edge. Now the place is so eroded that it looks more like part of the natural landscape. Clearly that's what this river otter thought too. He's the first otter to settle in San Francisco for over 40 years — which means that decades of water cleanup in the Bay Area are finally paying off.
Even when ecosystems are severely polluted and damaged, they can be rebuilt. Here's how scientists and environmental enthusiasts are helping to make broken environments whole again.
AP photo of the otter by Ben Margot.
Wolves in Yellowstone National Park
One way to think about an ecosystem is as a food web, or a set of relationships between living organisms that eat each other (or get eaten). Food webs unravel when the nodes in it — animals or plants — go extinct or leave the area. Often, nodes get knocked out of a food web due to human development that shrinks natural habitats, or pollution that contaminates it. To rebuild a food web, engineers and environmental scientists start by figuring out which nodes have gone missing. In Yellowstone National Park, for example, an important predator had disappeared: the common wolf.
In the mid-1990s, park workers reintroduced wolves to the area. As the wolves began to reproduce and grow their population, their presence helped bring back another creature, the beaver, who had almost disappeared from the environment. With more wolves eating elk and other large herbivores, there were more trees and bushes left for the beavers to eat and build with. Bringing back an important predator brought back an herbivore (and a cute one at that). Scientists and park workers continue to monitor the wolf population to make sure the new food web remains stable.
Photo of Yellowstone wolf pack bedding down from National Parks Service
Freshkills Park in Staten Island, New York — From Landfill to Wetlands and Meadows
Sometimes it takes a lot more than adding a lost species back into an ecosystem to start repairing it. An area may be full of pollutants or damaged by garbage. In the Freshkills Park in New York City, currently under construction, park workers and environmental scientists are using cutting edge engineering to turn a massive dump into the original wetlands and meadows that form the main habitats in this area.
To determine what needs to be done in a particular ecosystem, scientists use tools to measure the chemicals in the water and soil. Often, there are toxins that must be removed or neutralized before plants and animals can live in the area again. In the case of Freshkills, workers were dealing with a layer of pure garbage.
They had to build a new layer of rocks and soil on top of the trash, fitting it out with release valves that emit methane from the decaying garbage underneath. The methane gas will be sold to an energy company, and funds used to continue improving the park.
Presidio, San Francisco — Reverse Engineered Dune Ecosystems
There's another part to the cleanup efforts at Ocean Beach that brought Sutro Sam the river otter to the city. In the Presidio, an area that was a military base, the city is currently restoring a delicate dune ecosystem that was once the only environment you'd find in San Francisco if you left downtown and headed to the beach.
And they're doing it in what seems like the most unnatural way possible — by deliberately planting specific amounts of various dune plants in areas that are cordoned off with brightly colored string. And yet this very civilized method of planting will ultimately result in a wild landscape unseen in this area for a century.
Salt River in Phoenix, AZ — From Trashed Flood Control to Viable River Habitats
Working with the city of Phoenix, the US Army Corps of Engineers restored five miles of the historic Salt River from a trashed, dried-out riverbed used for flood control. And the best part is that the restored river and its various habitats — from wetlands to scrub- and mesquite-dominated ecosystems — run straight through the urban sprawl of Arizona's biggest city. You can find a great description of the multi-year project here.
Most of these projects are in urban areas, but there are many more in remote regions where toxic dumping has destroyed ecosystems that few people ever see. We are not yet at the point where we can say that for every ecosystem that humans have broken, there is another one that we are in the process of repairing. But we do currently have the tools and knowledge to repair every ecosystem we have damaged — and these projects are strong evidence that we can and should.
Want to help rebuild a broken ecosystem?
Most projects like these need community volunteers. You can find out more about restoration projects here:
Society for Ecological Restoration
Search for your local parks through the US Parks Service, and then look for "ecological restoration" or "environmental remediation" on the sites for those parks.
The US Environmental Protection Agency has a service to show you environmental cleanup sites in your area.
If you have more suggestions, add them in comments!