What is the situation/consistence of the water on the border of salt water to fresh water?
Rivers end up in oceans.
River water is fresh water, whereas sea water is saline.
What is the water like at the point where the river ends up in the sea?
Is there a physical/steady border (where the river stops being a river), or is the border there where the consistency of the water reached a certain level of salinity (or freshness)?
As a side question: do fresh water fishes feel/taste/notice that the river reached its end, and will they then turn around asap?
This question is in the General Section. Responses must be helpful and on-topic.