Quagga mussels invade your waterways!
Dreissena rostriformis bugensis is the accepted name for what is regarded as possibly the most dangerous AIS (alien invasive species) currently affecting us (and the rest of the environment.) Native to the vast watershed of the Dnieper, it has crossed like the Vikings to other watersheds and now sits worldwide as a hazard to waterways, fish, drainage and providing multiple other ecological threats to other animal species. Even zooplankton are starved, as the animal removes so much matter from their food supply, while phytoplankton, blue-green algae and all other plants tend to appreciate them, as the water becomes so clear that more photosynthesis can take place, blocking waterways with vegetation.
Its size at 2cm (or 0.8 in) gives no clue about its potential. It quietly filters particles from fresh water, just like its fellow IAS, the zebra mussel. But the big push from quaggas comes from their veliger larvae. They breed prolifically, and despite eating some of the millions of offspring, many tiny planktonic larvae continue to the furthest reaches of water systems. Up the St. Lawrence to all the Great Lakes, since 1989; throughout much of Europe and Asia and everywhere that ballast water can carry it in the ships that now cross every ocean. Even an angler, cleaning his equipment, could easily spread the nuisance to a new river system, if he discards it in an improper way.
As well as dominating the water quality, the mussel can eventually poison the ecosystem. Waste from it accumulates, lowers the pH (acidity) and robs the water of oxygen (bacteria decomposition.) Perhaps the greatest threat is accumulation of environmental pollution from the water, the quagga's tissues are very tolerant, but the faeces they become highly toxic to wildlife. Many species in freshwater suffer, but native fish and invertebrates are always believed to be most heavily affected. The economic effect is greater as docks, breakwaters, buoys, boats, and beaches are heavily infested as well insidious blocking of water intakes and pipes.
The Centre for Ecology and Hydrology in the UK have this year declared the quagga as "the top-ranking threat to our natural biodiversity." It's incredible that the animal has only just arrived - at Heathrow! More history of freshwater crayfish and many other "invaders" in these articles: IAS Species, Part I.