San Francisco Bay has been called the most invaded Estuary in the world. From Chinese mitten crabs to zebra mussels from Europe to Atlantic cordgrass from the East Coast, the Estuary has been colonized by myriad animals and plants from other parts of the country and world. Water hyacinth now clogs Delta waterways; Asian clams regularly consume all the fish food in the water column; water primrose is carpeting over native flora. Many alien animals arrived in ships’ ballast water or aquarium water dumped by unknowing home hobbyists while plants like Atlantic cordgrass were introduced intentionally by the U.S. Army Corps of Engineers in restoration projects, from which the plants then hybridized with Pacific cordgrass, creating a menacing invader. But eradicating these invaders has proved tricky. Resource managers employ both mechanical and chemical means of control, both of which can cause other, unintended consequences. Eradication and control programs also require long-term vigilance, with new species being introduced all the time, species that exploit the habitats of native species and outcompete them.
Morning at Suisun Marsh is a living watercolor with a soundtrack. Miles of tule and pickleweed populate the foreground, split by canals glinting silver from the sun. In May, the hills undulate across the northern boundary in classic California gold. A red-tailed hawk’s iconic hoarse screech punctuates the insectine buzz as it takes off from […]
A few weeks ago, someone working in a big-box pet store in the Seattle area informed the U.S. Geological Survey that they had seen suspicious mollusks in ornamental aquarium plants that were being offered for sale. Federal scientists confirmed the presence of zebra mussels tucked away in a clump of Aegagropila linnaei, a green alga […]
Wall-to-Wall Sampling of the Delta’s Aquatic Weeds Via Remote Sensing, an interview with Shruti Khanna. In this episode of the podcast, Estuary News reporter Daniel McGlynn talks to Dr. Shruti Khanna, a senior environmental scientist at the California Department of Fish and Wildlife. Their conversation focuses on Khanna’s use of remote sensing technology to study […]
Tobias Rohmer and Ben Chen’s careful work in Hayward’s Cogswell Marsh represents one small moment in the massive, nearly 20-year-old Invasive Spartina Project. Treatment of the southern section of Cogswell marsh was halted in 2011, however, due to concerns about Ridgway’s rails who’d made homes in the invader. “Complete eradication has been and still is our goal,” says Marilyn Latta…
On multiple fronts, with multiple forces and weapons, California’s battle against invasive aquatic organisms continues. Notoriously, San Francisco Bay is the world’s most invaded estuary. The state’s lakes, rivers, and other freshwater wetlands have their own problematic exotics. Keeping them out, and preventing their spread once established, requires coordination among agencies and levels of government.
Now in its 17th year of monitoring and treatment, the San Francisco Estuary Invasive Spartina Project remains a uniquely ambitious invasive plant removal effort: from its timeline (indefinite) and size (covering 70,000 acres with more than 150 landowners and managers) to its budget (about $50 million to date) and use of technology (genetic testing, GIS, […]
A study by UC Davis researchers found a 97% decline in phytoplankton, the microscopic foundation of the food chain. “Understanding the causes for the decline in the pelagic [water column] community is essential so that efficient solutions can be implemented,” says Bruce Hammock, a research scientist at the UC Davis School of Veterinary Medicine’s Aquatic […]
According to the California Department of Fish and Wildlife, nutria have extremely destructive feeding habits that often lead to severe soil erosion, in some cases converting marsh to open water. Nutria also burrow into banks and levees, creating complex dens that extend as much as 6 meters deep and 50 meters into the bank, often […]
Several months ago, Mike Moran of the Delta’s Big Break Regional Park got a call about a cluster of unusual looking eggs. “We thought we might be looking at this channeled apple snail thing,” he says.
“They’re pretty charismatic,” says Julie Hopper of the tiny herbivorous weevil N. bruchi. Native to Argentina, these weevils were first brought to North America to combat the spread of the invasive weed water hyacinth.
The Ocean 102 lab at Diablo Valley College in Pleasant Hill is a proper marine biological laboratory. It smells faintly of seaweed and formaldehyde, while fearsome, plastic versions of marine predators hang from the ceiling. The Peterson benthic grab, a heavy jaw-like affair attached to a long rope sits in the supply room.
Whether you’re a fat salmon or a skinny smelt, life in the watershed of the San Francisco Estuary remains far from “natural.” Dams and levees block Estuary fish, alien clams compete for fish food, invasive weeds clog habitats, and exotic predators threaten life and fin. A few native species are holding their own, but others, like Delta smelt, have declined to such a degree that there are too few to count. Clearly, we have failed to stem the decline and ensure the recovery of native fish as we set out to do twenty years ago.
Walk back through time with this selection of early stories from Estuary’s first two decades of publication. Stories explore the impacts of overbite clams, water hyacinth and mitten crabs, and later follow legislative efforts to control ballast water discharges and eradicate Atlantic cordgrass and hybrids, among other initiatives.