All swans gone

Whatever happened to the wildlife?
When I last visited Airthrey loch,  Stirling university a few weeks ago  there was only one swan left. Today it’s gone. A few years ago, I counted fourteen at this time of the year.
Is it anything to do with this ( see extra photo)?
The algae look treacherous, and it must be the only explanation for the disappearance of the swans.
According to American research there are several factors that encourage algae growth from change in climate temperature, to increase in nutrients in the water.
Nearly every day I come across examples of climate change effecting us personally. My next-door neighbours have just returned from Florence. They travel regularly to Europe and they say they had never experienced such violent thunderstorms and lightening, unheard of at this time of the year.