An observer strolling past the Jack London Square waterfront on a recent Saturday afternoon might have witnessed an unusual sight: A group of people on the dock, some of whom were lying on their bellies with their heads dangling just above the water, scooping up what looks like green and brown gunk. Others huddled over plastic Tupperware containers excitedly passing around hand lenses to peer at wriggling specimens.
They were among a group of about 30 attendees who gathered Nov. 8 to try out what’s known as dock fouling — observing the aquatic life that’s taken up residence underwater on the dock that are considered to be “fouling” it. In other words, they were looking up close at the mystifying and frequently difficult to identify marine creatures that live under the water attached to the docks. And they were having a blast.
“It’s special to see so much life, and worlds you’ve never seen before, in a place that’s so familiar,” said attendee Kristen Kellinger of Berkeley.
The star of these pop-up Tupperware aquaria was a white and orange swimming critter identified as a nudibranch, a type of brightly colored sea slug, some types of which can steal the stinging cells from creatures they eat and use them as defense against predators.
“It was spectacular,” said Christine Wolf of San Leandro, who said she’d been on a quest for decades to see one. As an appreciator of overlooked nature, she said looking under docks provides her with a new frontier to explore. “It’s a whole amazing world waiting to be discovered,” she said.
But the nudibranch wasn’t all the intrepid dock foulers pulled up. There was also the fearsome peanut worm, which, in lieu of a face, has a collection of Medusa-like tendrils waving around its mouth hole. It could’ve come out of a sci-fi novel. And then there was a pair of stick-like Japanese skeleton shrimp, which drew a collection of oohs and aahs when they started fighting.
And plenty of tunicates, a bugula and other animals not readily identifiable had also been scooped for observation. Emma Flickinger had traveled from Menlo Park to participate, and was looking closely at a worm with tendrils and a segmented body that nobody in attendance had ever seen before.
Bay Nature, the regional nature nonprofit that publishes a magazine of the same name and organizes nature-focused events around the Bay Area, was behind the gathering, organized to complement a recent article by former editor Eric Simons all about bugula, a type of bryozoan, or small invertebrate, that forms moss-like colonies and can be found by dock fouling.
Simons goes dock fouling regularly, often alongside his 10-year-old daughter, Margaret, and both were there to instruct visitors. “It’s really fun, and you can learn a lot,” Margaret said.
Yes, a trip to the California coast for tidepooling can be a naturalist’s dream outing, with its salt spray, native sea life and views of the sunset, waves and rugged cliffs. But there’s something special — and even a little transgressive — in instead plopping down on a nearby public dock along the bay to see what animals are living just below the water’s surface, Eric Simons said.
Sure, it can smell a bit funny, and it’s a more urban experience being amid the man-made docks and boats and the Oakland waterfront than the vast Pacific. But it’s got its advantages — convenience, for one, especially among East Bay residents. Plus, he said, what you do find in the Bay “tends to be on the weirder side.”
Additionally, unlike tidepooling, you don’t have to keep track of the tides to do it, since the docks rise and fall with the water levels, and you don’t have to deal with walking on slippery, rocky surfaces of the coastal tidal zone, said Bay Nature event coordinator Lia Keener.
In contrast, the conditions for dock fouling are more dependent on rain and seasonality — summer and fall tend to be a particularly good time to go since it hasn’t rained in a while and the water is saltier, and thus the saltwater creatures are thriving. The San Francisco Bay is considered one of the most highly invaded aquatic ecosystems in the world: According to some estimates, up to 90% of the species reported in the bay have been introduced from elsewhere.
“It is an indisputably human scene,” Simons said. “I like it for that.”
If you go:
Consider bringing a towel to lay on so that you don’t get bird poop or other dock grime on your clothing.
Bring a macro hand lens, or pick up a clip-on phone attachment you can use as a magnifying lens to aid in observing the details of the aquatic creatures you see.
Bring a small, flat plastic container. Lean over the edge of the dock, and scoop some water and gunk into the container. Wait and watch to see what swims out.
Citizen science apps like iNaturalist can help if you want to try to identify what you’re looking at. But to get down to the precise species level will likely be tough — these are creatures that probably only a handful of people around the world can identify, Simons said.
After you’re done, empty out your container, wash up and go pick up a bite — you’re in a perfect location for enjoying a meal out on the town.