The tidal flats of the Fraser delta are being menaced by highly invasive, non-native cordgrass that is threatening to turn rich ecosystems into a monoculture. Fast colonizing common cordgrass—Spartina anglica—is expanding rapidly in Boundary Bay and Roberts Bank and is moving up the coast. Larger infestations of cordgrass are being vigorously fought in Washington state and California, where they cost millions of dollars to control.
If you are strolling the dikes around Boundary Bay or Brunswick Point this summer you cannot miss the small, coloured flags sticking up across the tide flats. These mark the clumps, or clones, of spartina identified by work groups. Once the area has been surveyed, teams head out to dig up the bright green, metre-tall plants by hand or mechanical digger.
Originally from Europe, Spartina anglica flourishes in the inter-tidal zone and out-competes eelgrass and seaweeds, converting hectares of productive mud flats to monoculture meadows. If this were to happen in the Fraser delta, habitat for a whole host of small invertebrate species, such as amphipods, jellies, squids, clams, cockles, and snails, would be destroyed, ultimately affecting larger species up the food chain, including herring, salmon, otters, and whales. Millions of wintering and migrating shorebirds and waterfowl also depend on the intertidal habitat. Shorebirds fuel their incredibly long migration journeys on the Pacific Flyway with invertebrate prey and biofilms on the mud surface. Waterfowl feed on invertebrates, eelgrass, and the seeds of salt marsh plants. Spartina alters the topography of the beach, from a gentle gradient to uneven, steeply-sloping seaward edges, as sediment accumulates around the stalks and roots. The plants have been deliberately used for this purpose around the world and their introduction into non-native habitats caused the contamination of ecosystems.
In the Fraser delta, spartina plants collectively cover only about 0.4 hectares, yet they are scattered like freckles over more than 8,000 hectares of wet sand and silt. Locating and removing every root and stalk is a massive effort. The year 2018 has been targeted for total eradication of all spartina from California to B.C., and it is going to take some significant money and effort to do this. Amazingly, California and Washington have brought large infestations, covering thousands of hectares, under control in the last few years, using a combination of mechanical excavation and, more recently, targeted herbicide sprays. The effects have been dramatic.
Willapa Bay in Washington became infested with Spartina alterniflora decades ago. Between 1982 and 2002, it increased from 160 hectares to 8,000 hectares. Productive salt marsh and shallow open water became dense, sterile cordgrass fields and up to 20 percent of the key bird habitats were lost. A determined extermination program succeeded in reducing the coverage to only 2.8 hectares in 2011. In Puget Sound, where four non-native species of cordgrass are found, Spartina anglica was reduced from 400 hectares during the peak infestation in 1997 to just over three hectares today. These efforts were not cheap. For the period 2009-2011, the program cost Washington state US$4.5 million, plus extensive volunteer time by concerned citizens. Similarly, California spent US$2.65 million in 2009-2010 to eradicate 600 hectares of spartina in San Francisco Bay, a rate of over $4,000 per hectare.
The B.C. Spartina Working Group, a cooperative mix of conservation organizations and government agencies, has worked since 2003 to hold back the invasion tide from southern B.C. Originally, no clones were larger than a metre and most were small and scattered. It was hoped the problem would soon be gone. However, spartina is tenacious and unless every last piece is removed or deeply buried, it sprouts up again. Funding faded for a few years, and in 2010 the plants had regained their hold. Furthermore, for the first time in Boundary Bay, clones larger than five metres were found. The working group had in-kind contributions to cover project coordination, mapping, and public awareness but only about $70,000 cash to pay digging crews.
Dan Buffet, chair of the working group, works for Ducks Unlimited. He believes that spending more money now is strategically much better than waiting to get overwhelmed by the plant’s spread and will save money in the long term. He is hoping that more corporate sponsors will step up to the plate to help, as it is such a proactive way of benefiting the environment. Doubling the funding could ensure that the problem in B.C. continues to be handled by mechanical means, rather than having to consider herbicide sprays. If left unchecked, spartina has already proven that it is an expensive and difficult-to-eradicate menace, yet control appears to be possible given enough effort.
To identify or report spartina, you can consult the B.C. Community Mapping Network. Friends of Semiahmoo Bay Society volunteers discovered Spartina anglica at Blackie Spit this spring and provided funds toward the eradication effort.
Anne Murray is a naturalist and the author of two books on Lower Mainland nature and ecological history—Tracing Our Past: A Heritage Guide to Boundary Bay and A Nature Guide to Boundary Bay.