The monetary rewards for marine biologists range from not great to modest to somewhat okay. Right out of college, a graduate can expect to make around $30k each year. The more initials you have after your name, the more money you'll tend to make, though. Those with master's degrees bring home more dough, while a doctorate degree can get you around $80k-plus a year.
But don't forget location, location, location. What you pull in—salary-wise, that is—can depend on where you work. Those toiling in private firms tend to make more than those on the government dime, say $100k vs. $70k, at the top end of the salary scale.
The true reward for these intrepid marine biologists is the satisfaction that their work not only helps the environment now, but also well into the future. If you love the ocean, but really need to make the big bucks, steer clear of marine biology, and satisfy your love for the sea with a nice aquarium.
Please don't tap the glass.