Hello there!
Yes. It definitely is a good course.
The difference between Marine Microbiology and Zoology is in the course structure. Although these both are part of Life Science only and majority of the subjects are same but still, at higher level the difference arises.
You can become a lecturer in this field by clearing NET CSIR, Gate exams.
There is good scope ahead in both professional area as well as academic area.
Good Luck!