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.”

Ecosystem Invaders: Spartina
Spartina alterniflora grows out from the coast into the water.

Invasion: Lionfish
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.

abundant
Adjective

in large amounts.

adjacent
Adjective

next to.

animal
Noun

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.

Noun

body of water partially surrounded by land, usually with a wide mouth to a larger body of water.

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.

Noun

waterway between two relatively close land masses.

community
Noun

group of organisms or a social group interacting in a specific region under similar environmental conditions.

consequence
Noun

result or outcome of an action or situation.

cordgrass
Noun

aquatic plant.

creek
Noun

flowing body of water that is smaller than a river.

damage
Noun

harm that reduces usefulness or value.

discharge
Verb

to eject or get rid of.

drain
Verb

to empty.

dredge
Verb

to remove sand, silt, or other material from the bottom of a body of water.

Noun

community and interactions of living and nonliving things in an area.

eliminate
Verb

to remove.

environment
Noun

conditions that surround and influence an organism or community.

eradicate
Verb

to destroy or remove.

Noun

mouth of a river where the river's current meets the sea's tide.

Noun

process of complete disappearance of a species from Earth.

float
Verb

to rest on the surface of a liquid.

Noun

overflow of a body of water onto land.

forage
Verb

to search for food or other needs.

government agency
Noun

organization serving the government of a country or nation.

grass
Noun

type of plant with narrow leaves.

Noun

environment where an organism lives throughout the year or for shorter periods of time.

herbicide
Noun

natural or manufactured substance used to kill plants.

hybrid
Noun

the end result of two different sources of input.

imazapyr
Noun

herbicide used to control weeds.

Noun

type of plant or animal that is not indigenous to a particular area and causes economic or environmental harm.

marine
Adjective

having to do with the ocean.

Noun

wetland area usually covered by a shallow layer of seawater or freshwater.

meadow
Noun

wide area of grassland.

mechanical
Adjective

having to do with machinery or automated tools.

migrate
Verb

to move from one place or activity to another.

migratory
Adjective

organisms that travel from one place to another at predictable times of the year.

monoculture
Noun

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.

Noun

art and science of determining an object's position, course, and distance traveled.

Noun

substance an organism needs for energy, growth, and life.

opportunity
Noun

chance.

Pacific Flyway
Noun

route taken by many migratory birds of the Americas, stretching from Alaska to Chile.

pond
Noun

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.

seed
Noun

part of a plant from which a new plant grows.

shoreline
Noun

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.

starvation
Noun

dying from lack of food.

Noun

body of flowing fluid.

swath
Noun

path or line of material.

threat
Noun

danger.

toxic
Adjective

poisonous.

Noun

movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.