Wide Sargasso Sea?

Poole Park lake has been invaded by a mixture of blanketweed and tasselweed, giving the results shown. In some directions the lake looks more like a meadow now. It's apparently the result of higher temperatures plus more nutrients in the lake (which has a lot of associated swans and Canada geese). If you scoop it out (expensive) it grows more. You can't kill it cheaply or greenly. We seem to be stuck with it, for a while at least.
As a fellow-travelling environmentalist, what should I make of this? Is all nature good nature? (After all, it doesn't pose any threat to people, fish or wildfowl.) Is it a warning of climate change shifting our biosphere, and if so, should I learn to love the weed? Or am I right to have aesthetic longings for the clear blue water there used to be in the park?