Several years ago, The Watershed Project built oyster hotels: baskets full of Pacific oyster shell that were kept in a slip at the Marina Bay Yacht Harbor. A variety of marine invertebrates, including our native Olympia oysters as well as such characters as bay barnacles, yellow finger sponges, and sea lettuce, moved right in and colonized the shells. Recently, we teamed up with the Marin Rod and Gun Club to relocate our oyster hotels across the bay to the ¼ mile long pier that the private Club owns.
Our hotels are now more accessible, and we plan to use them as an educational tool for classes of schoolchildren. While our oyster reef at Point Pinole is also educational, it can be difficult to bring large groups of younger children out to the mudflats, especially with changing tides and weather. The hotels allow us to teach students about what is underneath the surface of the Bay during any tide. Just on the western side of the Richmond-San Rafael Bridge, a short walk down the pier now brings you to the hotels – and the view is pretty great too!
A couple of weeks ago we paid a visit to the Marin Rod and Gun Club to check in on the oysters, and brought an interested student along with us. His family had helped monitor the oyster reef this past fall, and he wanted to learn more about our native Olympia oysters. Below are a couple of questions that we were able to answer for him.
What do oysters like to live on?
Oysters need a hard surface on whic h to attach. Although they have been known to settle on pretty much anything, from car tires to old bricks, they can actually sense the presence of other oysters in the water based on calcium carbonate that is emitted from the shells. In this way, they can sense where oysters are already growing and can settle on top of the last generation, contributing to the reef. For our oyster hotels, we used the old shells of Pacific oysters as our hard substrate.
What eats oysters?
Besides humans, oysters’ main predators are fellow invertebrates, such as sea stars and the oyster drill snail, as well as birds like the oyster catcher. Now, you may be thinking, “How is a cute and cuddly sea star going to eat an oyster?” Well, sea stars are actually voracious predators, and a little thing like a shell doesn’t stop them from enjoying invertebrates. This is how it goes down: the sea star gets on top of the oyster and uses its sucker feet to pry open the shell a little ways. Then, it uses its extrudable stomach to pump digestive fluids into the oyster’s shell, waits for digestion to take place, and slurps up the contents. It’s a little different from our oyster shucker/half shell approach, but it gets the job done!
Thank you to the Marin Rod and Gun Club for welcoming our bivalve friends! If you are interested in coming out to see our oyster hotels or bringing a school group out on a field trip, please contact Helen@thewatershedproject.org.