Zebra Mussels as Fashion

Way back in the early 1990's, at the International Pearl Association (IPA) "Pearls '94 conference in Hawaii, Steven Ahlsted took a look at, what was then the growing problem of Zebra mussels in US rivers.  Ahlsted was with The Clean Water Initiative in Norris, Tennessee and his predictions that this was going to be a serious & growing problem, was correct.  He advised that, ecologically they were a serious threat to native freshwater mussel populations and, surprisingly to some, he said they were also a serious threat to the cultured pearl industry throughout the world. 

Photo: A clever soul had the idea to collect some of these invaders, drill and string them as an inexpensive necklace. click on the picture to enlarge it. Photo credit: Matt Arden

The zebra mussel, endemic to the Caspian Sea, was transported to the Great Lakes in ballast water and on the hulls of ships. Zebra mussels were first found in the Great Lakes in 1988, and in the Tennessee river in 1991.  However, in the Netherlands they first noted them in 1973.They are able to colonize very quickly (about 8000 can colonize a single washboard clam and suffocate it) and the females are capable of producing as many as 1 million eggs in 2 years!  In 1994 Ahlstead stated, "This small mussel with zebra-like stripes has the potential to become the most serious befouling post of any exotic species introduced into North America"   Sadly, his words have been prophetic.

Zebra mussels look like small clams with a yellowish-brown D-shaped shell, usually with alternating dark- and light-colored stripes and most are less than an inch. They usually grow in dense clusters containing hundreds of individuals and are generally found in shallow (6-30 feet), algae-rich water.  Apparently they are the only freshwater mollusk that can firmly attach itself to firm objects such as submerged rocks, dock pilings, boat hulls, aquatic vegetation, and water intake pipes.  And, sadly they can survive outside the water for 2 or 3 days in moist conditions. 

These days, those wishing to walk in Lake Michigan need to wear swimming shoes as they feel like razorblades under bare feet.  Looking at the Lake now, it is noticeably cleaner and clear.  This, however, is not a good thing, the mussels are removing all the nutrients in the water that other marine life feed on, as well as suffocating clams and mussels. They clog water intake systems so badly that most Departments of Water use scuba divers to clear off their equipment regularly.  They also cling to the hulls of boats, and in bilge water on ships (which is how it is believed they came to invade North America in the first place.

Kansas Dept. of Wildlife & Fishing has these preventative instructions: 

Preventing Their Spread

Boaters and anglers using El Dorado Reservoir, the Walnut River, or Winfield City Lake can prevent the spread of zebra mussels to other Kansas waters by carefully checking their boats and trailers. Any water in the bilges or live wells should be drained before leaving the lake. Mud attached to anchors or ropes should be removed, as should any vegetation on boats or trailers. If someone boats in zebra mussel infested water (El Dorado Reservoir, Walnut River, or Winfield City Lake), they should dry their boat for 5 days or clean it thoroughly with hot water (~140 degrees F). If hot water is not available, a 10% bleach solution can be used to kill any zebra mussels present. Bait should not be transported from El Dorado, the Walnut River, or Winfield City Lake to another lake. Instead, unused bait should be poured onto dry land. Never release bait into a lake, and don’t take bait from one lake to use in another. Anglers who wade to fish and duck hunters should clean their boots after leaving an infected lake. REMEMBER: it is against both state and federal law to release zebra mussels. Make sure you do not have zebra mussels or water from zebra mussel infested water with your equipment.