Padilla Bay

A number of invasive species exist within the Reserve, including estuarine and upland species. We use an integrated weed management approach for those species deemed noxious, assessing each infestation and using the best method for that particular site (physical, mechanical, chemical).

There are many invasive plants and animals in Padilla Bay. Just a few of the more notable ones are listed here. Scroll down for more detailed information about these:

More information is available in the Review of Non-Native Species [PDF] or contact the Reserve.

Cord grass (Spartina): Our total acreage of Spartina peaked in 1997 at about 17 acres. In 2003 we had less than a half-acre. We do an annual survey of the shorelines and presently can dig all but one infestation (which we mow/spray). S. alterniflora was planted in the 1940s on one island at the south end of the bay. We started treating the island in 1997 mowing a month prior to spray. In 2003, we had less than a half-acre to control. S. anglica was originally planted about 30 miles south near Camano Island. The seed has since spread around northern Puget Sound. We started treating the S. anglica infestation in Padilla Bay in 1996 by hand-pulling seedlings, digging clumps less than a foot in diameter and mowing/spraying clumps greater than a meter in diameter. In 2003, we were able to control the remaining S. anglica (scattered seedlings and clumps) by digging only.

Japanese eelgrass (Zostera japonica): This is a non-native seagrass, probably introduced with oyster culture. Its impact on the native seagrass, Zostera marina, is being studied. We do not try to control this species.

Canada thistle (Cirsium arvense): This plant occurs on our 64-acre upland site and on parts of the Demonstration Farm site. We used herbicide applications on parts of the infestation in 2000 and 2001. We mowed and pulled in 2002. We have yet to get this infestation under control.

Other invasive plants in the upland include: English Ivy, English Holly and a few plants on the Washington State Noxious Weed list.

Mud Snail (Batillaria attramentaria): This mud snail was introduced with oyster culture, probably in the 1930s. There are literally billions of them in the bay (O’Connor et al, 2001) and their impact is just now starting to be studied (Wonham, et al, 2001). Native hermit crabs (Pagurus granosimanus and Pagurus hirsutiusculus) use empty Batillaria shells.

Purple Varnish Clam (Nutallia obscurata): Commonly called the purple varnish clam, this clam is thought to be a ballast water introduction in British Columbia. The clam has spread southward over the last ten years and arrived in Padilla Bay about 5 years ago. Studies are being done to determine its impact.

Crabs: We presently do not have any invasive crabs. However, we have been monitoring for invasive crabs, namely the European green crab (Carcinus maenas) for the past two years. Using the Wash. Dept. of Fish & Wildlife protocols, we set minnow traps once a month at three sites in the bay April-September. We gain baseline data on native crab populations at the same time that we monitor for invasive crabs.

Other non-native species: We have other non-native species that were either introduced for their commercial value (Japanese oyster (Crassostrea gigas), Japanese littleneck (Venerupis phillipinarum) or that were introduced with those commercial species (worms, clams, etc.)