A vulcanologist
Volcanology is the study of volcanos. So a volcanologist is a scientist who studies them.
A biotechnology scientist.
An Oceanographer. Marine Biologist, that sort of thing.
A scientist that studies viruses is called a virologist.
A scientist who studies mollusks is called a teuthologist.
A scientist that studies bears would be called an ursinologist.
virologist
An aviologist.
A meteorologist.
biologist
Mineralogists
Bridgeologist