Pacific Oysters: Canary in the coal mine or a Chiuahuah in the Arctic?



The Pacific oyster's apparent inability to handle changes in the northwest's marine environment has been called a "canary in the coal mine." Environmental changes this species has difficulty with include an increase in a bacteria named Vibrio tubiashii and a decrease in the pH levels of the marine waters (aka "Ocean Acidification") from increasing CO2 levels.  Both cause problems with the Pacific oyster's ability to form a shell at the larval stage.  It has been assumed by the shellfish industry this is also why there have been no natural sets of Pacific oysters in Willapa Bay and why hatchery production dropped to near zero a few years ago.

With federal tax dollars, the hatcheries have installed various filters and ultraviolet systems to help contain Vibrio tubiashii.  Federal funds have also been used to purchase pH monitoring equipment for the hatcheries which has allowed water with a higher pH from various depths, at certain times of the day, to be drawn in.  Both have helped increase the production of Pacific oyster seed. 

Left open is whether forcing an oyster adapted to the warmer waters of Japan to survive in the colder northwest waters is analogous to raising a Chiuahua in the Arctic. Since the introduction of the Pacific oyster it has been known to have difficulties surviving the critical larval stage in the cooler northwest waters.  It was why seed had to be imported from Japan.  Wild sets in Willapa Bay occurred primarily due to its warming during the summer months, but even that was variable.  It is what drove the development of the hatchery industry in the northwest which created the artificial environment the Pacific oyster seed could survive in and then be used for transplanting. 

Layered on top of this is the development of genetically modified "triploid" Pacific oysters.  Forcing an extra set of genes into the Pacific oyster prevented its becoming "fertile" during the summer months (i.e., they are sterile).  This prevented the "plumpness" from the summer months' breeding most people find unpalatable.  The downside to this is a species less able to adapt to changes in the marine environment (i.e., being sterile, there are no progeny produced to survive and adapt to the changing environment).

A recent abstract from a 2011 Pacific Coast Shellfish Growers Association in Salem, OR  found that in waters with CO2 levels of the future, native Geoduck's larvae survived at higher levels than at current CO2 levels (read abstract from UW here).  Is the Pacific oyster really a canary in the coal mine, or simply a species being forced to grow in an environment it was not adapted to, like a Chiuahuah in the Arctic?