physical chemical biological etc conditions in fresh waters eg in lakes
A Mycologist studies fungi.
A person who studies audiology would be called an audiologist.
A scientist that studies motion, forces and energy would be called a physicist.
That would be a semanticist.
A person who studies potions would be called an alchemist or a potion maker.
This person would be known as a sociologist.
A person who studies reefs is called a marine biologist specializing in reef ecology.
A paleontologist is the type of person who would study fossils and dinosaurs.
A limnologist, or aquatic ecologist, would study algae in streams to determine if changes are occurring that could make the water unhealthy. They would analyze the type and abundance of algae present, as well as other water quality parameters, to assess the ecosystem's health and potential impacts on water quality.
a Marine Biologist is what you would call it.
That person would be called a scientist
Etymologist.