I am only passingly familiar with Scala, so the best I can do is evangelize a bit for Clojure. It's a great language, but take all this advice with a grain of salt as it's coming from an enthusiast.
If you are looking for concurrency, Clojure is fantastic both for ease of programming and for performance. The immutable data structures mean that it's trivial to work with a coherent snapshot of the world without any manual and error-prone locking; the STM makes it fairly simple to change data in a thread-sensitive way without breaking anyone else's snapshots.
My understanding is that Scala has a lot of the nice functional tools that Clojure does, but Clojure will always win syntactically by virtue of being a Lisp. If you're looking to do some specialized bioinformatics stuff, Clojure is able to hide the bits of Lisp that you don't want, and raise your own constructs to the same level as the built-in language constructs. I can't find the reference right now, but there's some well-known quote about Lisp that goes like:
Lisp is not the perfect language for any program. But it is the perfect language for building the perfect language for every program.
That's horribly paraphrased, but in my experience it has been true. It looks like you'll want a fairly specialized set of tools, and no language will make those feel as natural as a Lisp.
