Freshwater Jellyfish

The freshwater jellyfish, Craspedacusta sowerbyi, are indigenous to the Yangtze River Valley in China, as well as the Amazon river. It was first found outside of these habitats in England around 1880, and since 1908 have been found in about thirty US states. This species most likely gets to places other than these through shipments of plants and animals. As of now through research, these jellyfish are found on all continents except Africa. They can be found in lakes, reservoirs, quarries, and other freshwater bodies of water. They are able to reproduce sexually as well as asexually, which often times will result in an abundance of the species in one area. These jellyfish do no change the local ecosystem drastically as they are about the size of a penny and don't really have the ability to harm much. The biggest change the jellyfish have on the ecosystem is that they impact the zoo plankton species structure, and they may consume small amounts of fish eggs. The sting the jellyfish produces can kill or paralyze small fish, but the jellyfish can die just as easily if an animal runs into them. Under lab conditions, the jellyfish killed and fed on striped bass larvae, although they are not considered a threatening predator to eggs or small fish. The freshwater jellyfish are not considered dangerous to humans because they only contain a very small amount of toxin and their sting will only affect small creatures. Due to the lack of harm to humans as well as the environment, there is not much anyone is doing to reduce their appearances. A factor that may contribute to the sudden abundances of freshwater jellyfish is global warming, as they appear in large amounts when temperatures are suitable for a population outbreak. They are said to be found in many Maine lakes, but have only been collected from Androscoggin Lake in the Androscoggin and Kennebec counties.


http://www.state.me.us/dep/blwq/doclake/jelly.htm
http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=1068 
http://www.jellyfishfacts.net/freshwater-jellyfish.html