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.
The Mississippi silverside (Menidia audens[1]) is one of the
most abundant fishes in the San Francisco Estuary and in the
fresh waters of California in general. As the name indicates,
it is not native to the state but was introduced into Clear
Lake, Lake County, in 1967, from which it quickly spread
widely, via the California aqueduct system and through angler
introductions as a bait and forage fish (Moyle 2002). It is a
small fish, 7-12 cm (3-4 inches) adult length but typically
occurs in large schools. Its impact on native fishes is poorly
understood but is most likely negative. This blog tells the
story of how it came to be introduced, as a classic example of
the Frankenstein Effect, where a well-intentioned,
science-based introduction created an out-of-control monster.
Ask any of the wine grape growers planting own-rooted stock why
they’re farming these massively risky grapevines and they’ll
all tell you the same thing: They just want to make really
great wine. But there’s another benefit to the gamble,
too—unlike most American wine grapes, which are overwhelmingly
grown on grafted rootstock, own-rooted vines are especially
drought-tolerant, produce a more predictable crop and use
significantly fewer resources. There’s a huge downside to
using own-rooted vines, though. If they get attacked
by phylloxera, the entire crop will die. It won’t be a
loss of just one season’s grapes—the entire vineyard itself
will be totally destroyed. And the invasive species is present
in the soil in vineyards throughout America.
Federal dam managers are preparing a springtime assault against
smallmouth bass on the Colorado River, possibly using cool
water from deep in Lake Powell to keep the non-native fish from
getting entrenched in Grand Canyon. Environmental and river
recreation advocates hope the U.S. Bureau of Reclamation will
pair cold water with a rush of water from deep behind Glen
Canyon Dam, both disrupting bass reproduction around Lees Ferry
and restoring eroded sandbars farther downstream. That option,
officially under study, is politically sensitive because it
would cost hydropower production and move water out of a
reservoir that has dropped to about a quarter of its storage
capacity. The stakes for humpback chub and other native fishes
are high. Young smallmouth bass, which grow into voracious
warm-water predators, were found between the dam and Lees Ferry
last year…
An invasive fish species could begin swarming more areas of the
Colorado River, officials have warned. In a report released in
February by the Bureau of Reclamation, concerns are raised that
smallmouth bass—an invasive species established in Colorado
River reservoir Lake Powell—could escape into other reaches of
the river, below the dam. Lake Powell, formed by the Glen
Canyon Dam, is seeing some of its lowest water levels ever.
Officials are concerned that the low water levels will cause
the smallmouth bass to escape past the dam, which has so far
served as a barrier for the fish. When water levels are high,
the report said it prevents the fish passing through.
California State Parks’ Division of Boating and Waterways (DBW)
announced today its plans for this year’s Aquatic Invasive
Plant Control Program in the Sacramento-San Joaquin Delta and
its southern tributaries. Starting tomorrow, March 1, DBW will
begin herbicide treatments to control water hyacinth, South
American spongeplant, Uruguay water primrose, Alligator weed,
Brazilian waterweed, curlyleaf pondweed, Eurasian watermilfoil,
hornwort (aka coontail), and fanwort. These aquatic invasive
plants have no known natural controls in the west coast’s
largest estuary, the Delta. They negatively affect the Delta’s
ecosystem as they displace native plants. Continued warm
temperatures help the plants proliferate at high rates.
The U.S. Bureau of Reclamation is seeking public input on a
plan to prevent smallmouth bass from spawning downstream of
Glen Canyon Dam. Officials say the historically low levels in
Lake Powell result in warm water being released from the dam
which creates ideal spawning conditions for the predatory
invasive species. The bureau wants to prevent the bass from
establishing in the Colorado River between the dam and the
confluence of the Little Colorado River and could try to reduce
the water temperature and change the flow velocity from the
dam. Smallmouth bass are a major threat to native fish
including the federally protected humpback chub that live at
the confluence.
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.
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.
