“Aah! It’s moving!!” shrieks a student. “What is it?!” asks another. This is just an average day at the Point Pinole oyster reef, where high school students have been coming to learn about all things aquatic.
To clarify, it wasn’t an oyster that was moving: it was an amphipod, many of whom have joined the reef community in recent months. Amphipods, also known as scuds, look like tiny shrimp and are typically less than a centimeter in length. They enjoy a wide range of food types, including algae, other invertebrates, and even decomposing matter.
So why are these small crustaceans spending time on the reef? As more oysters, barnacles, algae and other life forms grow on the reef balls, it becomes prime real estate for small invertebrates who like to have a little shelter with their meal. The interwoven growth of life on the surface of the reef creates nooks and crannies that shelter small critters like amphipods, while keeping them close to the buffet of food options around them. As time goes on we expect to see the reef provide food and shelter for even larger life forms, including fish.
But back to the students, who are shin-deep in mud and touching all sorts of new and slimy things. They are part of our Wild! Oysters education program, and this is their first time at the Point Pinole oyster reef. These students are from Oakland, Mission, and George Washington High Schools. Once they get their bearings they divide into groups and decide on a scientific question that they will answer today. One group asks whether there will be more oysters near the bottom of the reef balls or near the top, while another wants to know whether they will find the same species on all of the reef balls. (A sneak peek into their results: they find more oysters near the top of the reef balls, and the same species on all of the reef balls.)
After lunch the students survey the shoreline, finding many large Olympia oysters. These populations have been growing for a long time and are part of a well-established community that incorporates many invertebrates, including amphipods, snails and even crabs. This survey provides a glimpse into the future of the reef balls, which will one day grow to support an even larger community of aquatic organisms.
Last, the students measure temperature, pH, salinity and water clarity in the bay. What follows is a discussion of why these water quality measurements are important not just for oysters but for all aquatic life. And finally, damp, muddy, and tired, the students leave the oyster reef with opened eyes and a new understanding of what lives just below the surface of the bay.