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Aquatic invasive
species both plant and animal pose a serious threat to the biological
diversity of coastal waters the world over. With improvements in
travel technology, the rate of introductions of nonnative species
has increased dramatically.
It is important
to remember that humans have carried plants, animals, and disease
with them since they first began to travel. Most of the plants and
animals were considered necessary or beneficial. This includes everything
from food crops like soybeans and wheat, cattle, horses, pigs, fish
and shellfish, to pets and decorative garden plants.
Many other
organisms have been spread to various parts of the world unintentionally.
They arrive in the ballast water of ships, packing materials, wood
used for pallets, soil, or as hitchhikers on other plants and animals.
Once nonnative
species become established in a new environment where natural enemies,
pests, or disease that kept them in check in their native environment
are missing, they may spread rapidly and cause unanticipated negative
biological and economic impacts. There are numerous examples of
the impacts of aquatic invasive species in both marine and freshwater
environments. One of the most well known species is the zebra mussel
(Dreissena polymorpha). The zebra mussel has caused extensive
economic and ecological damage since arriving in the Great Lakes,
and is rapidly spreading throughout North America. The Quagga
mussel, a sister species, is now present in Lake Mead (NV, AZ)
and Lake Havasu, CA., which greatly increases the risk of introduction
into Washington State. Readily observed examples of aquatic invasive
species in the inland marine waters of Puget Sound and the Georgia
Basin include cordgrasses (Spartina spp.), Japanese eelgrass, (Zostera
japonica), Oyster drill (Ceratostoma inornatum), varnish
or dark mahogany clam (Nuttalia obscurata), and the European
Green crab (Carcinus maenas). In the past two years three species
of non-native tunicates have developed rapidly expanding
populations in Puget Sound and Hood Canal. Freshwater invasive species
in Washington include Eurasian Water Milfoil (Myriophyllum
spicatum), the Asian clam (corbicula fluminea) and the New
Zealand mudsnail (Potamopyrgus antipodarum).
WDFW
Contact Information
Questions
or comments regarding the state’s Ballast Water Management
Program may be directed to:
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