In North America, zebra mussels (Dreissena polymorpha) are one of the worst aquatic invasive species. Originating from Russia and Ukraine, these small mollusks have spread all over the world as a result of their frequent transport in ballast water used to stabilize boats. They have caused billions of dollars in damage to fisheries, water treatment plants and other water industries by clogging inflows and stealing nutrients from ecosystems. Researchers have now uncovered a new method of invasion – hitchhiking fish.
The discovery was made by researchers last year while assessing fish communities in a lake in southeast Quebec. A lake mullet (Couesius plumbeus), a species of minnow usually around 12 centimeters long, was discovered with a zebra mussel stuck to it. The discovery, published this month in the journal Biological Invasions, is the only instance in which a larval-free freshwater bivalve has been found to attach to a fish. The mollusks used byssal threads to cling to the helpless minnow (seen above), protein fibers they also use to cling to plants, rocks, and concrete.
This finding is particularly worrying because fish are highly mobile species with no way to get rid of these parasites. The mullet and related species are routinely transported from one body of water to another as they are used as bait by anglers.
Researchers are concerned that although boaters and other users of infested waters are advised to wash their craft, remove adherent plant matter from their equipment, and dispose of the water they carry before moving to another body of water, bait users are probably unaware that they may be inadvertently carrying zebra mussels. They claim that this finding shows that more care may be needed to prevent zebra mussels from spreading to new areas.
Source: science
Günceleme: 10/03/2023 22:23