Continuing with the algae theme...haha just kidding.
Seriously though, algae are so important to the proper functioning of marine environments. And they can be intimately connected with its dysfunction as well.
Excellent article on algae blooms and genome sequencing from WHOI: http://www.whoi.edu/page.do?pid=7545&tid=282&cid=90450&ct=162
Enjoy.
