From 2000 to 2005, a non-native plant and its hybrid rapidly changed the makeup of California’s San Francisco Bay.
The invasive species, Spartina alterniflora, created an even more adaptable hybrid with its relative, the bay’s native marsh plant, Spartina foliosa. The hybrid threatened to turn tidal mud flats into meadow, eliminate shorebird foraging habitat, and push the native S. foliosa toward extinction.
Peggy Olofson, director of the Berkeley-based San Francisco Estuary Invasive Spartina Project, says the non-native S. alterniflora, also known as smooth cordgrass, was introduced to San Francisco Bay’s eastern shoreline by contractors and workers for the U.S. Army Corps of Engineers during the 1970s, as part of a dredging restoration program.
S. alterniflora, and especially its hybrid, quickly took over large swaths of the bay.
“In San Francisco estuary, we have thousands of acres of open mud flat, and many of the plants, the hybrids, decided they loved it there,” Olofson says. “So they started filling in all of the mud flats. They decided that they also liked the high marsh area, where there are just a couple of species that live native in our state. So they started taking over those areas and displacing the natives from those areas also.”
The native cordgrass was just one species S. alterniflora and its hybrid threatened. The invasive species changed parts of the bay where the endangered California clapper rail, a salt marsh bird, forages, and shrank the habitat of the endangered salt marsh harvest mouse.
The plants not only became a problem for animal species. One unexpected consequence of the hybrid was its ability to thrive in pond water. The number of biting mosquitoes increased dramatically, inconveniencing the local community and discouraging public use of the area.
The plants also began to change natural drainages in the Bay Area.
“One of the things that is a concern for people who were responsible for flood control and protecting human houses is that the plant clogs the storm channels, the channels that are tidal right by the bay where all of the creeks and streams have to discharge in order to get the storm water off the hillsides. It clogs those up and causes them to back up and causes flooding in the adjacent areas and the upland areas.”
Established by the California State Coastal Conservancy in 2000, the San Francisco Estuary Invasive Spartina Project set about eliminating S. alterniflora and its hybrid from the estuary. The project is a partnership between government agencies, environmental organizations, and individuals.
In 2005, the organization began eradicating the invasive Spartina with the herbicide imazapyr.
“This is a very low-toxic substance, which just happens to work very, very well on this plant,” Olofson says.
Due largely to the organization’s efforts, the footprint of the invasive Spartina and its hybrid has been reduced from more than 800 acres in 2006 to fewer than 90 acres today. Still, Olofson says the work is not done.
“Now that we are getting close to being successful with eradicating the hybrid, the marsh is left without any [native] foliosa,” she says. “What we are doing now is we are starting a very large re-vegetation program and going back and introducing the native cordgrass into areas where it was completely removed or displaced by the hybrid.”
Pterois volitans, also known as the red lionfish, is a native to the Pacific Ocean and was introduced to the Atlantic Ocean as early as 1985 by the way of the aquarium trade. Lionfish are a growing threat off the coast of North America because they have no natural predators and prey heavily on young reef fish, as well as juvenile snapper, grouper, and shrimp.
A universal call has been made to eradicate the invasive lionfish, and some surprisingly entertaining and unconventional methods top off the list. Lionfish derbies are being held, where fishermen and divers compete to catch the ravenous invasive, and an "Eat Lionfish" campaign has emerged to encourage a market for the flavorful fish.
Term Part of Speech Definition Encyclopedic Entry abundant Adjective
in large amounts.
organisms that have a well-defined shape and limited growth, can move voluntarily, acquire food and digest it internally, and can respond rapidly to stimuli.
Army Corps of Engineers Noun
government organization concerned with construction projects.
body of water partially surrounded by land, usually with a wide mouth to a larger body of water.
Encyclopedic Entry: bay Bay Area Noun
region surrounding San Francisco Bay in the U.S. state of California.
California clapper rail Noun
endangered species of salt marsh bird native to the central coast of California.
waterway between two relatively close land masses.
Encyclopedic Entry: channel community Noun
group of organisms or a social group interacting in a specific region under similar environmental conditions.
result or outcome of an action or situation.
flowing body of water that is smaller than a river.
harm that reduces usefulness or value.
to eject or get rid of.
to remove sand, silt, or other material from the bottom of a body of water.
community and interactions of living and nonliving things in an area.
Encyclopedic Entry: ecosystem eliminate Verb
conditions that surround and influence an organism or community.
to destroy or remove.
mouth of a river where the river's current meets the sea's tide.
Encyclopedic Entry: estuary extinction Noun
process of complete disappearance of a species from Earth.
to rest on the surface of a liquid.
overflow of a body of water onto land.
Encyclopedic Entry: flood forage Verb
to search for food or other needs.
government agency Noun
organization serving the government of a country or nation.
type of plant with narrow leaves.
environment where an organism lives throughout the year or for shorter periods of time.
Encyclopedic Entry: habitat herbicide Noun
natural or manufactured substance used to kill plants.
the end result of two different sources of input.
herbicide used to control weeds.
invasive species Noun
type of plant or animal that is not indigenous to a particular area and causes economic or environmental harm.
Encyclopedic Entry: invasive species marine Adjective
having to do with the ocean.
wetland area usually covered by a shallow layer of seawater or freshwater.
Encyclopedic Entry: marsh meadow Noun
wide area of grassland.
having to do with machinery or automated tools.
to move from one place or activity to another.
organisms that travel from one place to another at predictable times of the year.
the system of growing one type of crop.
mud flat Noun
area left bare by receding lake or tidal waters.
native species Noun
species that occur naturally in an area or habitat. Also called indigenous species.
art and science of determining an object's position, course, and distance traveled.
Encyclopedic Entry: navigation nutrient Noun
substance an organism needs for energy, growth, and life.
Encyclopedic Entry: nutrient opportunity Noun
Pacific Flyway Noun
route taken by many migratory birds of the Americas, stretching from Alaska to Chile.
small body of water surrounded by land.
restoration project Noun
project to restore an environment to its natural habitat.
salt marsh Noun
coastal wetland that is flooded with seawater, often by tides.
salt marsh harvest mouse Noun
endangered rodent native to California's San Francisco Bay Area. Also called the red-bellied harvest mouse.
part of a plant from which a new plant grows.
beach, or where a body of water meets land.
Spartina alterniflora Noun
swamp plant native to the eastern coast of the Americas, Africa, and Europe. Also called smooth cordgrass or saltmarsh cordgrass.
dying from lack of food.
body of flowing fluid.
path or line of material.
movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.