i want to do field research dealing with marine organism conservation. should i get a degree in marine biology?

Marine bio would be best, but also you could go for biology, wildlife ecology, or something similar. Try to find a school with a marine bio lab that you can volunteer in as an undergrad. You'd be off to a good start that way. Good luck!

Marine Biology would be a good one, but most universities don't offer it as an undergraduate degree. It would probably be more realistic to get a B.S. in Fisheries and Wildlife Biology, Environmental Science, Zoology, or Biology and then specialize in something like Ecology, Marine Biology, or Conservation Biology. You can declare a specific/custom area of specialization on a graduate degree as long as the university provides the courses deemed required by your graduate committee. Keep in mind that it's difficult to guide your own research without a graduate degree. With a B.S. you're mostly just following orders.