The Evolving Story
Science at the Piers:
Life under the Docks
Fall 2011
Exploratorium biologist Dr. Karen Kalumuck studies the tiny tunicates of San Francisco Bay.

While most of the attention at the site of the new Exploratorium has been focused on what’s been happening above the piers, interesting things are happening below as well. When new pilings were recently sunk at Piers 15 and 17, it was only a matter of days before underwater organisms began claiming the pillars as their own, and staff scientist Karen Kalumuck couldn’t resist the opportunity to take a closer look.

“I call that dock schmutz,” laughs Dr. Kalumuck, senior biologist at the Exploratorium. “It’s the sea life that attaches itself to docks, piers, pilings, and boat hulls.”

These life forms—which include barnacles, mussels, sea stars, and a host of barely visible creatures—plague boat owners and colonize structures built over water. For their invasive and potentially damaging behaviors, these organisms have also been dubbed the “fouling community.”

However foul, the life forms colonizing the very foundations of the new museum also present a gleaming opportunity: to conduct authentic scientific research onsite at the new bayside campus.

So where does “dock schmutz” come from, and what can we learn from it?

“Folks are generally well acquainted with ocean life—whales, dolphins, and fish, for example,” says Kalumuck. “But the vast majority of the ocean’s animals are invertebrates that spend early life as tiny, planktonic larva,” swept along with the currents until they are eaten or morph into their adult forms.

Hitchhikers Invade
In their planktonic stage, explains Kalumuck, these organisms can be carried in the bilge water of cargo ships, while their adult forms may cling to the ships’ undersides. “These unintentional hitchhikers can be transported thousands of miles from their native home. And without the normal checks on their growth in their native habitat, such as predators or adverse environmental conditions, these newly introduced species can thrive and propagate dramatically, at times threatening native species.”

Invasions by sea are nothing new for the San Francisco bay and delta. In fact, the area is one of the world’s most invaded aquatic systems, with estimates that 80 percent of its biomass is made up of non–native species. Some of these species end up clinging to any available underwater surface, from a pier piling to a plastic tile submerged for research purposes.

One Person’s Schmutz Is Another Person’s Science
Not far from the Exploratorum’s old home, near the yacht harbor, Kalumuck has submerged squares of PVC in order to mimic what happens on docks and pilings.

“By checking these PVC settling plates periodically, photographing them and identifying species,” says Kalumuck, “we can detect the beginnings of invasions, monitor the seasonal fluxes of the various organisms’ abundance, study the effects of known contaminants on the normal populations, and even indicate that some natural- or human-caused environmental change is leading to a shift in the normal complement and abundance of organisms.”

Dr. Kalumuck has been working with Associate Professor Dr. Sarah Cohen, who studies the population biology of marine organisms and their ecological and evolutionary genetics. Cohen and other faculty members at the Romberg Tiburon Center for Environmental Studies (San Francisco State University’s marine laboratory) are also interested in collaborating on research at the Exploratorium’s new waterfront location.

The museum’s new home will span a variety of aquatic environments. According to Dr. Kalumuck, the far end of the piers is “over relatively deep water, churning and full of oxygen,” while closer to the street, the piers sit over shallow, calmer water that contains less oxygen, “ideal venues to research a host of environmental effects on the animals and plants of the bay.”

Image of Pier 15 seen from the water
These photos show how rapidly organisms in the waters of the San Francisco Bay can colonize and grow on a PVC settling plate. The clear bubbles and orange blobs on the plate (shown below at 3 weeks and 8 weeks) are tunicates. Tunicates—which are animals, not plants—have proven to be valuable research subjects. The solitary tunicate Ciona intestinalis has had its genome sequenced, and has long been used as a model organism for studying embryonic development. The orange colonial tunicate Botryllus exhibits a rudimentary “self-nonself” recognition, a type of primitive immune system, and is a model of stem-cell differentiation.
Image of tunicates on settling plates at 3 weeks - beginning signs of biological activity
Settling Plate, 3 weeks
After 3 weeks in the water, the PVC plate shows a collection of individual clear and orange blobs—the beginnings of colonial tunicate colonies.
Image of tunicates on settling plates at 8 weeks - lots of biological activity
Settling Plate, 8 weeks
At 8 weeks, large areas of orange and clear blobs show tunicate colonies thriving on the settling plate. The clear bubbles are solitary Ciona intestinalis, one of a common species of tunicates used in research labs.