Petaluma scientist’s research uncovers hidden creatures, aims to protect Bay Area waterways
Andrew Chang lay on his stomach on one of the piers at Petaluma Marina and plunged his arm into the cold, brackish water of the Petaluma River. The Petaluma resident reached under the dock and grabbed a handful of tiny living things that look like something Dr. Seuss would dream up.
“Tubeworms, sponges, mussels, algae. These are all invasive species that compete for food and habitat with the native species,” said Chang, 42, displaying the creatures for me to inspect. “They’re plankton-eating filter feeders that came from another part of the world, most likely by hitching a ride on boat hulls, in the ballast water used to balance cargo ships, or even in plastic garbage that drifts across the ocean.”
Invasive species, even such tiny organisms, can wreak havoc in the local marine ecology by competing with native species for food and habitat, and potentially cause significant economic burden to humans as well.
For over 20 years Chang and his team of marine biologists at the Smithsonian Environmental Research Center lab in Tiburon have patiently studied these tiny marine critters.
“I love the process of science and being able to do science!” Chang said. “I love going out there and learning about what's going on underwater and seeing how things are changing.”
One method he and his team uses is to submerge a plastic panel tied to a brick at some of the sites they study.
“We do this at 15 sites in the Bay-Delta every year,” he said. “Then we come back weeks, months, or even years later and see what’s growing on it. We identify these organisms by their shapes and characteristics, often under the microscope. We also use genetic information. We do this methodically over and over again, year after year.”
This painstaking research also shows the impact of climate change — which has brought the extreme weather and high temperatures we’ve seen in California in recent years — on marine ecology.
“For example, the amount of rainfall affects the amount of freshwater that pours into the Bay from the rivers, changing the salinity of the Bay water,” Chang explained. “Some of these organisms are sensitive to those changes. We’ve seen invasive species that showed up all over the Bay one year but disappeared in another when conditions changed.”
People may think of marine biologists donning scuba gear and going to faraway places to study dolphins or whales, but a lot of important work also happens along our home shores.
Chang grew up just north of Baltimore near Chesapeake Bay, the location of the Smithsonian Environmental Research Center’s headquarters. Like the San Francisco Bay, it’s a hotspot for invasive species due to the high volume of recreational boats, commercial vessels, and other human activities. The research center conducts multi-year projects that require long range commitment, maybe for decades.
Since the 1960s, Chang’s agency has collected information on over 500 invasive species, and built open-access databases on plants and animals in coastal marshlands.
“Funding these kinds of projects can be a challenge because it doesn’t seem ‘sexy’ until years down the road,” Chang remarked.
But he knows well that investing in long-term science is worthwhile.
“When I was a child, every Christmas our family got a box of macadamia nuts from Uncle John Chin, who was my mother’s uncle in Hilo,” he remembers. “It always came with a note that said ‘Carbon dioxide level is 338.77 ppm’ or whatever.”
Chang’s great uncle, John F.S. Chin, worked for the U.S. Geological Survey in the Mauna Loa Observatory on Hawaii Island from 1963 through 2000, where his team measured the carbon dioxide level in the atmosphere.
“I didn't think much more about it until I got to college, where I learned about climate change and carbon dioxide levels,” Chang recalled. “And lo and behold, there it was in the textbook! The graph of the measurements uncle John took, year after year.”
Decades of careful observation provided critical evidence for climate change.
“Right now, we’re beginning to test the effectiveness of the 2004 California law that requires management of ballast water in ships,” Change said. “This law requires vessels arriving from another part of the world to discharge ballast water in the open ocean before entering U.S. ports. “The idea is that coastal organisms, sensitive to the salinity, temperature, and other environmental conditions, will not survive in the mid-ocean waters,” Chang explained. “We’re now able to compare with data we collected before the law was enacted to see how well it works. We don’t have the final conclusion yet, but it’s looking promising so far.”
Chang is enthusiastic about this slow, patient work and understands its importance in the long term.
“What really keeps me going,” he said, “is knowing that our work can help guide policies to protect the environment.”