According to this from the NSF have been sequencing DNA from a range of planktonic microbes living at depths from 40 to more than 13,000 feet:
The interdisciplinary research team sequenced a total of 64 million base pairs, or subunits, of DNA from microbes and viruses they collected at each depth. In the process, they discovered thousands of new genes from novel and ecologically abundant microbes and found evidence of frequent gene exchange between organisms. The study also revealed variations in genetic composition at different depths–including differences among genes involved with carbon and energy metabolism.
Microbes near the ocean surface, for example, had more genes devoted to taking in iron, a major element necessary for growth in that zone. Genomes from organisms below the ocean’s deepest and darkest layers displayed almost epidemic levels of DNA associated with “jumping genes,” or pieces of DNA that can move from one part of the genome to another.
“Plants and animals are twigs on the tree of life when compared to the diversity of microbes that surround us,” said Matthew Kane, director of NSF’s microbial observatories and microbial genome sequencing programs, which also supported the work. “By approaching ecology through genomics, we are starting to get a truly paradigm-shifting view of all life on the planet.”
Interesting, for the most part I have heard very little about how this kind of large scale DNA sequencing is going to affect ecology…