In 1849, the Gold Rush brought over 700 ships carrying fortune-seeking gold miners to the San Francisco Bay Area looking to “strike it rich.” Little did they know that historical events like this, and a boom in the maritime industry, would bring an influx of vessels carrying tiny aquatic hitchhikers. Today, after a century and a half of maritime industry, San Francisco Bay is now home to more invasive species than any estuary in the world.
Global shipping traffic in and out of San Francisco Bay continues, which means a higher risk of introducing more invasive species, such as the burrowing isopod Sphaeroma quoyanum, to the Bay from their attachment to the hulls of ships visiting our massive harbor. While this isn’t the only way that species are moved in and out of ports, it’s a major contributor to a worldwide problem.
From microalgae to barnacles, organisms attach themselves to the surfaces of ships, a process which scientists call “biofouling.” Biofouling affects everyone who has a stake in the health of San Francisco Bay. In addition to spreading non-native species, when marine life attaches to a ship’s hull, it increases drag, lowering a ship’s fuel efficiency. Lowered fuel efficiency leads to higher exhaust emissions, which both damages the environment and increases operating costs for the maritime industry.
Researchers like myself want to understand these migrating microscopic organisms, like those attached to the underside of a 65,000 DWT Panamax Tanker ship crossing the Pacific from Asia and travelling up through San Francisco Bay. I work at San Francisco State University’s Estuary & Ocean Science Center, with Dr. Andy Chang of the Smithsonian Institute and Dr. William Cochlan of San Francisco State University, where we are measuring how such long voyages through widely different ocean conditions affect these hitchhikers.
While many scientists have studied larger organisms such as barnacles and mussels, we chose to narrow the scope of our work (well, using the microscope, to be precise), focusing on less-studied organisms — microscopic algae — as scientists still don’t know much about the impacts of their journeys across the seas.
We employed remotely-operated vehicles, and collected samples of algae to figure out how diatoms — tiny single-celled photosynthetic algae, and some of the first colonizers to attach to ship’s hulls — were impacted by a change in environmental conditions while hitchhiking across the South Pacific Ocean on the Training Ship Golden Bear. The ship left the California State University Maritime Academy in Vallejo, CA during its summer 2018 training voyage, and was sampled at Long Beach, CA, Lahaina HI, and finally again at Vallejo, CA.
We found that while the microalgae were negatively impacted by high temperature, salinity, and light exposure in Lahaina, HI, they were able to recover by the time the ship returned to Vallejo, CA. Conversely, we observed that all that attached barnacles had perished by the time the ship reached Hawaii, and did not recover once the ship’s voyage ended in Vallejo, CA.
Later, we studied biofouling communities under controlled, laboratory conditions at the Estuary & Ocean Science Center to determine how these organisms reacted to massive changes in salinity from the relatively fresh waters of the Bay to the much saltier waters of the open ocean. Despite exposure to high and low salinity, microalgae were resilient to extreme shifts in environmental conditions.
Regulations developed by the California State Lands Commission are intended to limit marine invasions, but microfouling on operational shipping vessels is a poorly studied area. Using evidence provided from our research, regulators can now better assess which vessels are more likely to spread non-native species, and therefore warrant further inspection.
Our research on biofouling, and the development of microalgal communities on ships, provides the scientific understanding necessary to address the spread of non-native marine species on a global scale. On a smaller scale, it wouldn’t hurt to have one less invasive clam show up in SF Bay.
The first author, Chrissy Edmiston is a Master of Science graduate student at San Francisco State University’s Estuary & Ocean Science Center in Tiburon. Her co-authors, Dr. William Cochlan — a Research Professor in the Biology Department, and Dr. Andrew Chang — the Program Leader at the Smithsonian Institution are based at the EOS Center as well. Chrissy will be defending her MS Thesis research later this year as one of the first students to graduate in SFSU’s new graduate program in ‘Interdisciplinary Marine and Estuarine Science (IMES)’ funded by the U.S. National Science graduate training initiative (RIPTIDES) awarded to SFSU in 2016. Chrissy can be reached at firstname.lastname@example.org. This is part of a series of stories looking at the bay and ocean around us through the eyes of researchers at EOS.