I'm studing for my bachelor's degree in Natural Science and I have to chose the path for my future life. I have to chose the right kind of graduate studies. Since I love computer science, maths and marine biology more in details I love the tropical ecology especially that of the coral reefs and atols in the pacific ocean, the whales (e.g. the humpback whales and their migrations), the computer simulations and mathematical models. Thus, I want to ask you if is there a branch of marine biology that allow me to study and specialize myself in tropical ecology and in math & computer science too, because in my current course we don't have any exams of computer science and only one of maths, and I'm feeling sad for this. The right path coul be the computational biology? Exist in biology, some field called "Computational Marine Biology" or "Computational Marine Tropical Ecology"? One last thing, what about Ecoinformatics?
This advice is America-centric; graduate programs in other countries may be different, especially in regards to assigned course work, etc. But this should more-or-less be solid. Also, I'm assuming you're interested in a PhD.
I don't know if what you're looking for is a proper field, but that doesn't matter. Ideally, grad school is where you do research on your own terms, and what lab you join is the single most important consideration. What you want is a competent program that:
First, find faculty who are doing research you are interested in, and look at the programs available at their schools. Since they're the most important consideration, everything else will fall into place after that.
Next, email 5 of those professors with an introduction of what you're interested in, particularly about their research. Ask them what programs are most appropriate at their university, and how flexible you can be in taking appropriate coursework.
At some point, you'll probably want to decide if you want to be more of a marine biologist or a computer scientist. Your diploma at the end of the decade is only going to say one of those things. That shouldn't make a huge difference as to your job outlook, but is worth thinking about. Practically, the question is whether you want to get your hands dirty, go out on a boat, and collect your own data. Alternatively, if you join a CS program, you are more likely to be analyzing large datasets collected by other scientists.
At most universities, you'll likely only have the option to join a biology program. But there are certainly excellent CS programs with biology oriented faculty. Even then, the CS faculty is more likely to be doing genomics and such.
For practical recommendations, the University of Washington in Seattle would probably have something appropriate to your interests. While I was there, my lab was adjacent to an Oceanography lab that had a video wall for visualizing ocean currents and such. Not precisely marine biology, but UW has a very collaborative faculty and I'm sure the two departments work together.
UW also has a strong computational biology program that you can go into either through CS or through one of the many biology programs. You should also check out the Institute for Systems Biology at UW. I saw a presentation there specifically about DNA exchange between marine microorganisms. I'm not saying UW is your best option, I just know that school because I did my PhD there.
A final word of advice. Once you're in a program, it's very likely your interests will change as you learn about other research going on. And also, it's quite possible you won't get into the lab you want simply because of money or logistics. With both of these in mind, be flexible about where you're willing to go. What you do during your PhD isn't really that important anyway. If you're going to be research scientist, it's what you do during your Postdoc that will establish your career. Just take the opportunity to learn everything you can and see what's out there.
Hope this helps. Good luck!
Alexander's advice is excellent in the general case, but since I faced a very similar problem when I applied to grad schools last year, I wanted to offer my perspective on this specific union of fields. Many people (including me) believe that this intersection is about to be a really important field - ecologists are starting to recognize the need for scientists with these skills, but there is not yet a lot of infrastructure in place to train such scientists. This presents a challenge to people like you and me right now. On the other hand, it means that if we can find a way to acquire these skills, we should be pretty well set up to help establish this field (bonus: we should be pretty well set up to get jobs).
I am personally of the opinion that if your interests are truly interdisciplinary, it's a really good idea to go somewhere that has a framework in place to support interdisciplinary work. Otherwise, you can end up in a situation where your adviser doesn't feel equipped to offer guidance on large portions of your projects, which can strain your working relationship and stymie your progress. Despite the lip service paid to the importance of interdisciplinary research, however, programs that are set up to provide interdisciplinary mentoring can be hard to find. The best course of action depends very specifically on how you want to combine these fields.
If you want to stay rooted in biology and use computer science and math as tools without doing research that furthers them as fields, you're in luck. There are a lot of labs with PIs who do this kind of research and many more who are interested in finding people who can, as terdon said, "do their modeling." I would be careful of the latter scenario while you're still in the learning phase of your career, however. As a student, your goal should be to learn how to best do the research that you want to. If you are the lone modeler/math person in a group, you may be in high demand but your rate of learning will probably be a lot slower than if you had an adviser who was actually doing what you are interested in. If these are your interests, your options are pretty varied but take a look at UC Berkley, and UC Davis. Also UW, as Alexander suggested. There are indeed good collaborations between biology and computer science there. I found it helpful to search for people who were studying macroecology, but that might be a label that is used more for terrestrial systems.
However, if you want to do research that actually furthers computer science in addition to biology, things get more complicated (I don't know if there are people who do both math research and biology research so I can't speak to that). Don't constrain your thinking by believing that you have to get a degree in one or the other; dual degree programs exist (and that may sound intimidating, but they aren't necessarily more work, just different work), although they are so few and far between that you might decide that it makes the most sense to just choose one field. If this is what you want to do, take a look at UC Santa Barbara - they do a ton of marine bio research and are home to the National Center for Ecological Analysis and Synthesis. Also, again, UW. I'd recommend my program too, but it's neither marine nor tropical.
In general, if you want to get a feel for how open a lab is to you doing interdisciplinary research, I found that it was best to just ask explicitly. If a place offered joint appointments (i.e. the ability for me to be co-advised by professors in two departments), dual degrees, or even just had research groups that involved people from multiple departments, I took that as a great sign.
In summary, don't start out with low expectations for finding a match for your interests. That said, it will ultimately be valuable to be flexible, as both finding a perfect match and getting accepted to it definitely requires a lot of luck. The considerations that I've brought up here won't make or break your grad school experience or your eventual career. They're just things to keep in mind if you have the option. I also apologize that it's probably a bit late in the application season for this to be useful to you, but I had such a horrible time grappling with these same issues that I just wanted to put what I learned out there in case it can help anyone.
EDIT: I forgot to address ecoinformatics! Ecoinformatics can fall into either the "computer science as a tool" category or the "furthering both computer science and biology" category, although it falls into the latter category much more frequently than modeling does. It still all comes down to what exactly you want to do. Look at research in computer science journals. If doing that sort of thing appeals to you as much as biology research, then you should be thinking about trying to pursue both fields. I found doing some pure computer science research helpful for figuring this out, but you probably don't have time for that.