Coastal urbanization could boost biodiversity

Environmental DNA surveys found higher diversity of clams and mud-dwelling species in populated Puget Sound.

 

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at 

Puget Sound, the twisting inlet that separates Seattle from the Olympic Peninsula, bears the heavy tread marks of the human footprint: concrete sea walls line the shore; farms have replaced wetlands; and so much terrestrial pollution runs into the water that salmon . It’s obvious that humans have altered the landscape, but quantifying how the changes have helped or hindered the region’s complex ecosystem isn’t easy. “We never quite know what to count in the world,” acknowledges , an ecologist and lawyer at the University of Washington. “If you’re interested in environmental impacts, should you look at snails, or orcas, or neither?”

Technological advances offer a new way to tackle that question. By measuring traces of genetic material (such as skin cells and feces) that animals shed as they move through their environment, researchers can now survey thousands of species at once with scarcely more effort than it takes to dip a bottle in seawater. In a survey using this so-called “environmental DNA,” Kelly and his colleagues found, perhaps counterintuitively, that —at least not for all creatures.

Gulls in flight at the Protection Island National Wildlife Refuge in Washington.
Peter Davis/U.S. Fish and Wildlife Service Pacific Region

The new study represents the latest twist in a years-long investigation of environmental DNA, or eDNA, by Kelly and his colleagues. Beginning in 2014, the researchers used eDNA to identify the occupants of a giant tank at the  and, later, to  in Monterey Bay. Having demonstrated the technique’s potential, Kelly turned his attention closer to home. For their most recent analysis, Kelly’s team collected one-liter water samples from eight Puget Sound eelgrass estuaries. The estuaries were fed by streams surrounded by different degrees of development, from dense Seattle neighborhoods to rural Vashon Island. Then Kelly’s crew took the samples back to the lab for analysis—where they received a surprise.   

Kelly detected the genetic signatures of 1,664 different species in the Puget Sound samples, from porpoises to barnacles. Although one might expect biodiversity to be highest in pristine watersheds, that wasn’t what the researchers found. Instead, the richest collections of species congregated along more urban beaches. The trend was largely driven by a high diversity of clams and other mud-dwellers. “That might suggest that urbanization is somehow subsidizing those habitats—creating muddier mudflats, if you will,” Kelly says.

But don’t start advocating for paving over coastlines just yet. The researchers also found that the species composition changed little from point to point within the more urbanized sites, like adjacent suburban subdivisions chockablock with similar-looking houses. And, as always, correlation doesn’t equal causation: just because developed sites have more mud-loving bivalves doesn’t mean urbanization should get the credit. “It could mean that humans tend to settle in more protected areas that have these mudflats,” Kelly says.

While the study’s conclusions may be murky, the potential of its method is unambiguously exciting. Among the intrigued scientists is , an ecologist at the University of Washington. McDonald was not involved in the new eDNA study, but he hopes to apply the technology to his own research on the  on Puget Sound’s shoreline, and on the possible arrival of voracious . McDonald has set up a  to scour Washington’s coastline for the invasive crustaceans, and he says the addition of eDNA surveys could expedite the squad’s needle-in-a-haystack hunt.

“Right now—before [the crab] has really gotten established—is the best time to stop an invasion, but also the hardest time to detect it,” McDonald says. “The value of eDNA is that if we were able to detect a green crab signal in an estuary, we could put additional effort into that location.”

Kelly, too, is beginning to explore new eDNA horizons. An upcoming project, designed to understand how ocean acidification affects ecosystems, will sample coastal sites in Washington and British Columbia, where the upwelling of acidic waters is already . “DNA should allow us to see, in a fairly sensitive way, how changing water chemistry is affecting these communities, and what we might be able to do about it,” Kelly says. “This technology should be very important in linking science with policy.”

Read more coastal science stories at , such as: 

  • .
NewTowncarShare News Classifieds
  • Background: The Birds of Prey NCA Partnership is a non-profit 501(c)(3) organization based in Boise, Idaho, which was established in 2015 after in-depth stakeholder input...
  • Southwest Borderlands Initiative Professor of Native Americans and the News Media The Walter Cronkite School of Journalism and Mass Communication at Arizona State University is...
  • AWF seeks an energetic Marketing and Communications Director. Please see the full job description at https://azwildlife.org/jobs
  • The Southwest Communications Director will be responsible for working with field staff in Arizona, Colorado and New Mexico to develop and execute detailed communication plans...
  • An intentional community designed for aging in place. Green built with Pumice-crete construction (R32), bamboo flooring, pine doors, T&G ceiling with fans, and maintenance free...
  • (CFROG) is a Ventura County, CA based watch-dog and advocacy non-profit organization. cfrog.org
  • Take your journalism skills to the next level and deepen your understanding of environmental issues by applying for the 2019-2020 Ted Scripps Fellowships in Environmental...
  • WINTER WILDLANDS ALLIANCE POSITION ANNOUNCEMENT: EXECUTIVE DIRECTOR Winter Wildlands Alliance seeks an experienced and highly motivated individual to lead and manage the organization as Executive...
  • The San Juan Mountains Association is seeking a visionary leader to spearhead its public lands stewardship program in southwest Colorado. For a detailed job description...
  • The Cascade Forest Conservancy seeks a passionate ED to lead our forest protection, conservation, education, and advocacy programs.
  • Mountain Pursuit is a new, bold, innovative, western states, hunting advocacy nonprofit headquartered in Jackson, Wyoming. We need a courageous, hard working, passionate Executive Director...
  • The Draper Natural History Museum (DNHM) at the Buffalo Bill Historical Center of the West in Cody, WY, invites applications for the Willis McDonald, IV...
  • Couple seeks quiet, private, off-grid acreage in area with no/low cell phone service and no/low snowfall. Conservation/bordering public lands a plus. CA, OR, WA, ID,...
  • 20mi N of Steamboat Springs, majestic views, aspen forest, year-round access, yurt, septic, solar electric, seasonal ponds, no covenants, bordering National Forest. Ag status. $449K....
  • Former northern Sierra winery, with 2208 sq.ft. commercial building, big lot, room to expand.
  • The dZi Foundation is seeking a FT Communications Associate with a passion for Nepal to join our team in Ridgway, Colorado. Visit dzi.org/careers.
  • Available now for site conservator, property manager. View resume at http://skills.ojaidigital.net.
  • Stellar seed-saving NGO is available to serious partner. Package must include financial support. Details: http://seeds.ojaidigital.net.
  • 1400 sf of habitable space in a custom-designed eco-home created and completed by a published L.A. architect in 1997-99. Nestled within its own 80-acre mountain...
  • Suitable for planting hay, hemp, fruit. Excellent water rights. 1800 square foot farmhouse, outbuildings, worker housing.