is dying. Almost dead now. The algae cannot grow in the water, it will suffocate. There is not enough total dissolved oxygen gas. It has leaped out of the water and survives by wicking water up to it as the algae lives exposed to air containing oxygen. Sometimes bubbles connect with the algae and pop carrying water with oxygen gas to the algae.
There is no aquatic life. No algae, no insects, no frogs. Decaying leaves litter the bottom.
Normally there would be a fine green furry layer of algae covering these surfaces.