Yes thats right these are the Russians which are invading and occupying the Thames - zebra mussels. According to the BBC there is an explosion in their growth triggered by warmer water. Its not a minor issue - they are classified as an invasive species in parts of North America.
These zebra mussels were first found in the Thames as far back as 1824 no doubt having fallen off one of the thousands of vessels using the great docks of London. The docks were so busy then that in 1800 when 1,775 vessels tried to dock where there spaces for only 545 ships there were delays of one or two weeks (*).
Yet another reason to try to combat climate change to stop the warming of our planet!
(*) history lesson from Peter Ackroyd's Thames.