WHAT ARE AQUATIC INVASIVE SPECIES (AIS)?
Aquatic Invasive Species (AIS) are organisms introduced into habitats where they are not native. Species introduced into new habitats often overrun their new home and crowd out native species. Once established, they can rarely be eliminated. Some have even caused the extinction of some native species.
HOW DID THEY GET TO THIS COUNTRY?
Within the ballasts of fast ocean freightliners, AIS survived the journey across the oceans to the Great Lakes, which is how most AIS have spread to the United States. But now AIS is being spread throughout our continent’s interior in and on boats and other recreational watercraft and equipment. Unfortunately, some introductions, such as carp and flowering rush, were intentional and were thought to be harmless and even beneficial.
WHAT ARE THE MOST PROMINANT AIS IN MINNESOTA AND WHAT IS BEING DONE TO STOP THEIR SPREAD?
In alphabetical order, these are:
ASIAN CARP- The term “Asian carp” is primarily used to describe the invasive bighead and silver carp. Black and grass carp (also from Asia) are not considered to pose any imminent threat. Both species have very small body scales, low-set eyes and large upturned mouths. They can weigh up to 100 pounds and grow to a length of more than four feet. Silver carp are renowned for leaping out of the water. Both species of carp were brought to the U.S. from China in the early 1970’s to improve water quality by removing algae from ponds, and to be marketed as a food fish. Both species escaped into the Mississippi River from southern aquaculture facilities in the early 1990s when the facilities were flooded. Steadily these carp have made their way northward to lakes, rivers, and streams, particularly in the Mississippi River and Great Lakes region. These carp are fast growing, often consuming plankton equal to their weight in one day. In eating plankton, these fish directly compete with mussels and fish, disrupting the food web in a water body. Control has focused on electrical barrier systems to repel them. Also, the University of Minnesota researchers are evaluating the possible release of sterile fish or pheromones to reduce their numbers.
CURLY-LEAF PONDWEED- This was accidentally introduced along with the common carp. It forms surface mats that interfere with aquatic recreation. Curly-leaf pondweed was the most severe nuisance aquatic plant in the Midwest until Eurasian watermilfoil appeared. Mechanical harvesting and approved herbicide applications are the only means for control.
EURASIAN WATERMILFOIL- This milfoil was accidently introduced to North America from Europe and spread westward into inland lakes primarily by boats between the 1950’s and 1980’s. It can form thick underwater stands of tangled stems and vast mats of vegetation at the water’s surface interfering with water recreation and the growth of native plants. A key factor in the spread of this plant is its ability to reproduce through stem fragmentation and runners. A single segment of stem and leaves can take root and form a new colony. The mechanical clearing of these plants creates thousands of fragments that can take root, so mechanical harvesting must be done with great care. Approved herbicide treatment is the most feasible, but expensive, means of control.
FLOWERING RUSH- This is a perennial plant from Europe and Asia that was introduced as an ornamental plant. It grows in shallow areas of lakes as an emergent and as a submersed form in water up to 10 feet deep. Its dense stands crowd out native species like bulrush. The emergent form has pink, umbellate-shaped flowers, and is 3 feet tall with triangular-shaped stems. Mechanical harvesting and approved herbicide applications are the only means for controlling flowering rush.
PURPLE LOOSESTRIFE- Purple loosestrife is a wetland plant from Europe and Asia, introduced into the east coast of the U.S. in the 1800’s. One adult plant can disperse 2 million seeds annually, so eradicating an established stand is difficult because of the enormous number of seeds in the soil. It can also resprout from roots and broken stems. Spreading naturally, but also having been distributed as an ornamental, it is now found in 40 states and all Canadian border provinces. This plant invades marshes and lakeshores forming dense, impenetrable stands which are unsuitable as cover, food, or nesting sites for native wetland animals such as ducks, geese, frogs, toad, and turtles. Many rare and endangered wetland plants and animals are also at risk. Biological control focused on finding insects that only attack loosestrife is being tested as a possible long-term solution to controlling this invasive.
SPINY WATER FLEA- This spiny water flea, or “B.C.”, is not an insect at all, but a tiny (less than half an inch long) crustacean with a long, sharp, barbed tail spine. A native of Europe and the Caspian Sea, this animal was first found in Lake Huron in 1984, probably imported in the ballast water of trans-oceanic freighters. Since then, populations have exploded and are found throughout the Great Lakes and in some inland lakes. Spiny water fleas reproduce rapidly and compete directly with small bait fish for food.
ZEBRA MUSSELS- Zebra mussels and a related species, the Quagga mussel, are small fingernail-sized mussels native to the Caspian Sea region of Asia. They were discovered in Lake St.Claire near Detroit in 1988. Tolerant of a wide range of environmental conditions, zebra mussels have now spread to all of the Great Lakes, the Mississippi River, and many inland lakes by attaching to transported boats and other lake equipment. Last year In Minnesota, super spreader lakes like Minnetonka, Gull, and Mille Lacs became infested with zebra mussels. Smaller lakes have also become infested such as Pelican Lake, Prior Lake, and the Alexandria chain. Female zebra mussels produce as many as 1 million eggs per year which eventually develop into larvae called veligers. In three weeks these larvae attach to any firm surface such as rocks, docks, lifts, boat hulls, native mussels, and even aquatic plants. These non-native pests cause millions of dollars of damage and lost revenues by destroying boat hulls, clogging water intakes, and eventually getting into irrigation intakes, sewer treatment facilities, and hydro electric plants. They eat the plankton that baitfish need, causing game fish populations to significantly decrease. They multiply exponentially, ruining lake bottoms and beaches with their razor sharp shells. At this time, control of zebra mussels involves boat inspections, draining water from boats, and penalties for not complying.
SPECIAL FOCUS ON ZEBRA MUSSELS
In collaboration with the Water Planning Task Force and the Kandiyohi County Board of Commissioners, a grant was received by the KCLA to fund projects related to preventing the spread and infestation of bodies of water by aquatic invasive species (AIS). Part of that grant went toward the production of a Power Point presentation titled “Zebra Mussel Impacts” by Dick Sternberg, a former senior fisheries biologist in the Minnesota Department of Natural Resources (DNR). Mr. Sternberg has written several books about freshwater fish and fishing techniques. His books have earned him national and regional awards with an estimated 10 million copies sold and he is considered one of the country’s top fishing authors and educators.
In recent years, Mr. Sternberg has devoted most of his time to conservation efforts, and was instrumental in establishing the Minnesota DNR Roundtable which gives fishermen more voice in water quality and fish management decisions. His latest creation, the “Zebra Mussel Impacts” production has been presented to numerous lake associations and groups around the state of Minnesota with the most recent presentation being at the DNR Roundtable on January 8, 2011. In addition to DNR staff, several state representatives and legislators were in attendance at that meeting. It was reported that the presentation made a tremendous impact and is undoubtedly one of the primary factors drawing attention to the need to put aquatic invasive species at the top of the state’s agenda. Below is Dick Sternberg’s “Zebra Mussel Impacts” Power Point presentation, his interview with Ron Schara on WCCO, and recent news articles related to aquatic invasive species (AIS).