The National Geographic reported that a crustacean is invading the lakes and eating planktons which leave small fishes nothing to feed on. This species is called the Bythotrephes longimanus or also known as the spiny water leaf which measures half an inch, making it a titan in the world of phytoplanktons.
Spiny water flea has a single black eyespot, mandibles, and a prominent tail that is 70% of its entire length. They are commonly found in Lake Ladoga, near the Baltic Sea in Russia.
Records show that these invasive parasites had reached Lake Ontario in the early 1980s when European ships released ballast into St. Lawrence River. It then infested Lake Superior by 1987 and now has been established in smaller lakes. They mainly prey on Daphnia and other planktons.
Effects of Spiny Water Flea
The population of plankton in Minnesota's lake has decreased by as much as 60% since it was infested with the spiny water flea, according to recent studies. In turn, it has affected other animals like the yellow perch, walleye, and other native game fish.
Additionally, fish in those lakes grow more slowly during the first year of their life, making them more vulnerable to predators. Spiny water flea is a voracious predator of plankton, which is the main food of all young fish.
They reproduce rapidly through asexual reproduction, which means that males are not required for their populations to grow. They easily grow in numbers during the warm weather wherein they could produce at least ten new ones in just two weeks.
According to the Lake George Association, the ability of spiny water flea to reproduce quickly enables them to monopolize the food source, which leaves other fish with no more food and affects their growth.
Even if these parasites can be eaten by fish, their spiny tail makes it for fish to swallow, presenting an ecological disadvantage to other species in the lake.
Lastly, they collect in masses on fishing lines and downrigger cables which can clog the first eyelet of rods, damage the drag system of a reel, and prevent the fisher from catching any fish.
Where Are They Located?
The first spiny water flea in North America was discovered in Lake Huron in 1984. It rapidly spread in the Great Lakes like Lake Ontario in 1985, Lake Michigan in 1986, and Lake Superior in 1987.
Then in 2008, some of them were discovered in Great Sacandaga Reservoir in New York, whose outlet is just 20 miles west of Lake George. The following year, experts have also found these parasites in Peck Lake, then Stewarts Bridge Reservoir in 2010, and then in Sacandaga Lake in 2010 also.
Another batch was found in Glens Falls Feeder Canal and Lake Champlain Canal in 2012. Two years later, spiny water flea was also spotted in Piesco Lake and Lake Pleasant.
A report from Lake George Association said that spiny water flea follows the plankton, wherein it stays deeper during the day and surfaces at night time. Also, they said that it is most likely that these creatures can be found about 10 to 20 meters deep in the main part of Lake George.