Invasive species, also known as exotics, are plants, animals,
insects, and aquatic species introduced into non-native habitats.
Without natural predators or threats, these introduced species
then multiply.
Often,invasive species travel to non-native areas by ship,
either in ballast water released into harbors or attached to the
sides of boats. From there, introduced species can then spread
and significantly alter ecosystems and the natural food chain as
they go. Another example of non-native species introduction
is the dumping of aquarium fish into waterways.
Invasive species also put water conveyance systems at risk. Water
pumps and other infrastructure can potentially shut down due to
large numbers of invasive species.
A California ecosystem has gotten a big boost from an adorable,
fluffy and hungry friend. At Elkhorn Slough National Estuarine
Research Reserve, a newly-reinvigorated population of native
southern sea otters has eaten so many invasive European green
crabs that researchers say the otters have locally solved a
problem that has plagued the West Coast for years. States are
spending millions to protect their inland waterways from the
tiny crabs. Though small – they reach only four inches in width
– the invaders harm native wildlife and shoreline ecosystems.
At stake are multi-million dollar shellfish industries for
Dungeness, king crab and other species. But at the reserve,
otters have almost wiped the crabs out, helping the estuary’s
ecosystem come back into balance.
The California Fish and Game Commission (Commission) acted on a
variety of issues affecting California’s natural resources
at its Dec.11-12 meeting in Sacramento, including
emergency action to list the invasive golden mussel as a
restricted species. The Commission also acted to extend
emergency regulations 90 days for the recreational
catch-and-release white sturgeon season and added language for
permitted catch handling. The public was able to participate in
the meeting in person, via webinar and by phone. To protect
California against the spread of invasive golden mussel
(Limnoperna fortunei) discovered Oct. 17 at the Port of
Stockton, and in the days following as far south as San Luis
Reservoir’s O’Neill Forebay, the Commission added golden
mussel to the list of species restricted from live
importation, transportation and possession. This discovery is
North America’s first; golden mussel is native to China and
Southeast Asia and was likely transported across the ocean on
large ships.
Although sea otters are an unofficial mascot of the Monterey
Bay area and popular among tourists and locals alike, they are
also described by scientists as voracious predators that help
keep problematic invaders out of coastal waters. A recent study
was published in the scientific journal Biological Invasions,
detailing that otters at the Elkhorn Slough are keeping
populations of globally invasive green crab at bay. … Green
crabs were first found at the slough in 1994 and the population
peaked in the early 2000s. Since then, the population has
declined and hasn’t reached the peak numbers again. Meanwhile,
the population of sea otters has risen. Sea otters were
recovering from near extinction in California in the early
2000s. The new study is first-time evidence that the recovery
of the otters is benefitting the overpopulation of invasive
species.
An invasive species in the San Joaquin County Delta is putting
water officials on high alert. Despite its name, the golden
mussel isn’t native to the Golden State, but instead to
Southeast Asia. Now, some lake boat ramps and launches are
closed, to try and keep the invasive species at bay. The
mussels were first detected upstream on the San Joaquin Delta
back in October. Officials say it likely got here from an
international shipment into the port, and it’s the first time
this species has been found in North America. Underneath the
ripples and waves of the San Joaquin Delta, the invasive
species is threatening the surrounding wildlife.
U.S. Rep. Joe Neguse introduced legislation on Tuesday aimed at
boosting efforts to slow the spread of highly invasive aquatic
species in waterways across Colorado and the West, following
the detection of zebra mussels in several locations on the
Western Slope this summer. …. Bennet and Daines have
introduced several versions of the bill dating back to 2019.
Colorado Parks and Wildlife announced in July that testing had
confirmed the presence of zebra mussel larvae, known as
veligers, in the Colorado River and in the Government Highline
Canal near Grand Junction. The species poses an “extreme risk”
to water ecosystems because it strips plankton, an essential
food source, from the water. Adult zebra mussels can also
threaten water supplies and irrigation systems by impeding or
stopping water flows and attaching to infrastructure, causing
millions of dollars in damages and increased maintenance costs.
After the recent discovery of a destructive mussel in the
Sacramento-San Joaquin River Delta, some experts say California
officials have failed to effectively enforce laws designed to
protect waterways from invaders carried in ships’ ballast
water. A state law enacted 20 years ago has required
California officials to inspect 25% of incoming ships and
sample their ballast water before it’s discharged into
waterways. But the tests didn’t begin until two years ago —
after standards for conducting them were finally set — and
testing remains rare. State officials have sampled the ballast
water of only 16 vessels out of the roughly 3,000 likely to
have emptied their tanks nearshore. Experts say stronger
regulations are needed, as well as better enforcement.
A newly detected invasive mussel is posing a potential threat
to Lake County’s water bodies. The Lake County Water Resources
Department, and Watershed Protection District urge residents
and visitors to Clear Lake, and other Lake County water bodies,
to be aware and on the lookout for invasive golden mussels
(Limnoperna fortunei). The newly detected invasive mussel
(freshwater bivalve) found in several locations in the Port of
Stockton and in the Sacramento-San Joaquin Delta region. On
Oct. 17, the California Department of Water Resources reported
finding attached, adult mussels at a sample site location in
the Port of Stockton. Mussel specimens were sent to UC Davis
Genomic Variation Laboratory and confirmed to be golden
mussels, originally from China and Southeast Asia; the species
had not previously been detected in North America.
Colorado wildlife officials keep putting up geographic and
psychological barriers to the noxious water weed Eurasian
watermilfoil, and the voracious invader keeps busting right
through. The fast-growing water floater — the bane of
Colorado handlers for nearly two decades — now has been found
in Pueblo’s Fountain Lake, near the Interstate 25 and U.S. 50
intersection, and its outlet into the broader Arkansas River.
The announcement is the first major spread of milfoil in
Colorado since a 2022 invasion of Boulder Reservoir, and opens
up the southeastern part of the state to all sorts of
trouble.
A large, fast-breeding rodent that tears through wetlands and
crops has raised alarm among Solano County officials and
farmers. Nutria, which may grow up to 2 feet long and weigh 20
pounds, were discovered in the Central Valley as early as 2017,
after going undetected for 40 years in California. But recently
they’ve multiplied. State Fish and Wildlife efforts have
captured a total of 5,171 nutria across 10 counties, including
Stanislaus, Fresno, San Joaquin, Mariposa, Sacramento, Contra
Costa, Madera, Tuolumne and Solano. The fear is they will
migrate to other North Bay areas beyond the Suisun Marsh,
specifically into sensitive wetlands and watersheds, such as
the Napa-Sonoma Marshes Wildlife Areas, San Pablo National
Wildlife Refuge and San Francisco Bay.
In the vast labyrinth of the West
Coast’s largest freshwater tidal estuary, one native fish species
has never been so rare. Once uncountably numerous, the Delta
smelt was placed on state and federal endangered species lists in
1993, stopped appearing in most annual sampling surveys in 2016,
and is now, for all practical purposes, extinct in the wild. At
least, it was.
This tour guided participants on a virtual journey deep into California’s most crucial water and ecological resource – the Sacramento-San Joaquin Delta. The 720,000-acre network of islands and canals support the state’s two major water systems – the State Water Project and the Central Valley Project. The Delta and the connecting San Francisco Bay form the largest freshwater tidal estuary of its kind on the West coast.
Nutria are large, beaver-like
rodents native to South America that have caused alarm in
California since their rediscovery along Central Valley rivers
and other waterways in 2017.
The growing leadership of women in water. The Colorado River’s persistent drought and efforts to sign off on a plan to avert worse shortfalls of water from the river. And in California’s Central Valley, promising solutions to vexing water resource challenges.
These were among the topics that Western Water news explored in 2018.
We’re already planning a full slate of stories for 2019. You can sign up here to be alerted when new stories are published. In the meantime, take a look at what we dove into in 2018:
Sixty percent of California’s developed water supply
originates high in the Sierra Nevada mountains. Our water
supply is largely dependent on the health of our Sierra forests,
which are suffering from ecosystem degradation, drought,
wildfires and widespread tree mortality.
We headed into the foothills and the mountains to examine
water issues that happen upstream but have dramatic impacts
downstream and throughout the state.
GEI (Tour Starting Point)
2868 Prospect Park Dr.
Rancho Cordova, CA 95670.
For more than 100 years, invasive
species have made the Sacramento-San Joaquin Delta their home,
disrupting the ecosystem and costing millions of dollars annually
in remediation.
The latest invader is the nutria, a large rodent native to South
America that causes concern because of its propensity to devour
every bit of vegetation in sight and destabilize levees by
burrowing into them. Wildlife officials are trapping the animal
and trying to learn the extent of its infestation.
Estuaries are places where fresh and
salt water mix, usually at the point where a river enters the
ocean. They are the meeting point between riverine environments
and the sea, with a combination of tides, waves, salinity, fresh
water flow and sediment. The constant churning means there are
elevated levels of nutrients, making estuaries highly productive
natural habitats.
A troublesome invasive species is
the quagga mussel, a tiny freshwater mollusk that attaches itself
to water utility infrastructure and reproduces at a rapid rate,
causing damage to pipes and pumps.
First found in the Great Lakes in 1988 (dumped with ballast water
from overseas ships), the quagga mussel along with the zebra
mussel are native to the rivers and lakes of eastern Europe and
western Asia, including the Black, Caspian and Azov Seas and the
Dneiper River drainage of Ukraine and Ponto-Caspian
Sea.
This 24×36 inch poster, suitable for framing, explains how
non-native invasive animals can alter the natural ecosystem,
leading to the demise of native animals. “Unwelcome Visitors”
features photos and information on four such species – including
the zerbra mussel – and explains the environmental and economic
threats posed by these species.
This 24×36 inch poster, suitable for framing, explains how
non-native invasive plants can alter the natural ecosystem,
leading to the demise of native plants and animals. “Space
Invaders” features photos and information on six non-native
plants that have caused widespread problems in the Bay-Delta
Estuary and elsewhere.
The 24-page Layperson’s Guide to the Delta explores the competing
uses and demands on California’s Sacramento-San Joaquin Delta.
Included in the guide are sections on the history of the Delta,
its role in the state’s water system, and its many complex issues
with sections on water quality, levees, salinity and agricultural
drainage, fish and wildlife, and water distribution.
