PAs 10 Least-Wanted Aquatic Nuisance Species

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					                                                     Round goby (Neogobius melanostomus)
                                                     Origin: Introduced from Europe into the Great Lakes in
                                                     1990 from the ballast water of an ocean-going ship.
                                                                                                                                                       Aquatic Nuisance Species (ANS): Aquatic animals
                                                     Description: Small bottom-dwelling fish.                                                          and plants that have been introduced into new ecosystems. ANS
                                                     Concerns: Round gobies are aggressive feeders and can                                             have harmful effects on the natural resources in these ecosystems
                                                     find food in total darkness. The round goby takes over
                                                     prime spawning sites traditionally used by native species,                                        and the human use of these resources.
                                                     competing with native fish for habitat.
                                                                                                                                                       These are the most aggressive nuisance species that have invaded
                                                                                                                                                       Pennsylvania’s aquatic habitats. All have negative effects on
                                                                                                                                                       Pennsylvania’s native plants and wildlife. Every effort should be
Zebra mussel (Dreissena polymorpha)
Origin: Introduced from Europe into the Great                                                                                                          made to halt their spread.
Lakes in the 1980s from the ballast water of an
ocean-going ship.
Description: Small fingernail-sized freshwater
Concerns: Zebra mussels colonize on                                                                                                                Purple loosestrife (Lythrum salicaria)
surfaces, such as docks, water intake pipes                                                                                                        Origin: Introduced from Europe in
and native mollusks. Their only known                                                                                                              the early 1800s as an ornamental
predators, some diving ducks, freshwater                                                                                                           garden plant.
drum, carp and sturgeon, are not plentiful                                                                                                         Description: Tall-stemmed plant with
enough to have a significant effect on their                                                                                                       lance-shaped leaves. A spike with
                                                                                                                   Spiny water flea                pinkish-purple flowers tops each stem.
numbers. Zebra mussels have greatly affected                                                                       (Bythotrephes cederstroemi)
the Great Lakes ecosystem and economy.                                                                                                             Concerns: Purple loosestrife has been
                                                                                                                   Origin: Introduced from         found in all major river drainages in the
                                                                                                                   Europe into the Great           state. It can invade a wetland and quickly
                                                                                                                   Lakes in 1984 from the          crowd out native vegetation. It has little
                                                                                                                   ballast water of an ocean-      or no value for wildlife.
                                                                                                                   going ship.
                                                                                                                   Description: Small
                                                                                                                   plankton-eating crustacean,
                                                                                                                   slightly larger than one                                                                 Asian clam (Corbicula fluminea)
                                                                                                                   centimeter (0.4 inches) long.                                                            Origin: First introduced from Asia to the West Coast of North
                                                      Sea lamprey (Petromyzon marinus)                             More than two-thirds of                                                                  America around 1924. By the 1970s, the clam occupied most of the
European ruffe (Gymnocephalus cernuus)                Origin: Native to the North Atlantic region and
                                                                                                                   this length is a long,                                                                   Mississippi Basin, the Gulf Coast and eastern United States.
Origin: Introduced from Europe into the Great         introduced into the Great Lakes early in the 20th century.                                                                                            Description: Small freshwater mollusk.
                                                      Description: Primitive eel-like parasitic fish.               barbed tail spine.
Lakes in 1985 from the ballast water of an                                                                                                                                                                  Concerns: The Asian clam causes serious water supply problems,
                                                      Concerns: Even though this species is native to the          Concerns: The rapid
ocean-going ship.                                                                                                                                                                                           affecting power and water suppliers and other industries. Asian
                                                      Susquehanna and Delaware River basins, the sea               reproduction of this
Description: Small fish, close relative of the                                                                                                                                                              clams are drawn into intake pipes and block water flow.
                                                      lamprey has had a devastating effect on Great Lakes          species, lack of predators,
yellow perch.
                                                      fisheries, where it is non-native. It is a direct parasite    and competition with young
Concerns: Because of its aggressive nature,
                                                      on large game fish.                                           fish for food may greatly
the ruffe has the potential to devastate both                                                                                                                                                                     Red-eared slider
                                                                                                                   change the food webs of the
perch and walleye fisheries by competing for                                                                                                                                                                      (Trachemys scripta elegans)
                                                                                                                   Great Lakes.
food and habitat.                                                                                                                                                                                                 Origin: Native to the southeast
                                                                                                                                                                                                                  United States. Established
                                                                                                                                                   Eurasian watermilfoil                                          populations are the result of the
                                                  Hydrilla (Hydrilla verticillata)                                                                 (Myriophyllum spicatum)                                        release of unwanted pets.
                                                  Origin: Introduced from Southeast Asia in the                                                    Origin: Introduced from Europe in the 1800s.                   Description: Medium-sized
                                                  1960s, probably through the aquarium trade.                                                      Description: Submerged aquatic plant.                          freshwater turtle with a bright-red
                                                  This plant was first reported in Pennsylvania in                                                 Featherlike leaves have reddish-brown tips.                    stripe immediately behind the eye                            Photo credits: Round goby, Dave
                                                  the mid-1990s in Adams and Bradford counties.                                                    Concerns: This plant grows so densely that it                  on each side of its head.                                    Jude; Asian clams, U.S. Geological
                                                  Description: Submerged aquatic plant with finely                                                 becomes poor fish habitat, clogs propellers, and               Concerns: The red-eared slider                               Survey; zebra mussels, J. Ellen
                                                  toothed leaves. Resembles common elodea.                                                         restricts swimming. Eurasian watermilfoil is                   competes for food and habitat                                Marsden; Eurasian watermilfoil, spiny
                                                  Concerns: Hydrilla spreads quickly and creates                                                   common throughout the state, but less common in                with Pennsylvania’s native                                   waterflea, Minnesota Department of
                                                                                                                                                                                                                  turtles. This competition could                              Natural Resources; purple loosestrife
                                                  mats of vegetation that are extremely dense.                                                     the Northeast where native watermilfoils still thrive.
                                                                                                                                                                                                                                                                               (left), Ted Walke; purple loosestrife,
                                                  These mats may crowd out native vegetation.                                                                                                                     affect sensitive populations of                              M. Walter, Michigan Sea Grant;
                                                                                                                                                                                                                  native turtle species.                                       European ruffe, Gary Cholwek; red-
                                                                                                                                                                                                                                                                               eared slider, photo courtesy of U.S.
                                                                                                                                                                                                                                                                               Geological Survey; hydrilla, California
                                                                                                                                                                                                                                                                               Department of Food and Agriculture;
                                                                                                                                                                                                                                                                               sea lamprey, Great Lakes Sea Grant.

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