OK here is some more very interesting information.
Based on this information I would be very embarassed to have my name on the article that started this thread.
The thermal vents are putting off a tremendous amount of heat. I would strongly suggest googling the below article.
Thermophilic Sulfate Reduction in Hydrothermal Sediment of
Lake Tanganyika, East Africa
LARS ELSGAARD,l* DANIEL PRIEUR,2 GASHAGAZA M. MUKWAYA,3 AND BO B. J0RGENSEN4
Universite Pierre et Marie Curie, Paris 6,1 and Centre National de la Recherche Scientifique,2 Station Biologique de
Roscoff, F-29682 Roscoff; France; Centre de Recherche en Sciences Naturelles, Station d’Uvira, Uvira, Zaire3;
and Max Planck Institute for Marine Microbiology, D-2800 Bremen 33, Germany4
Received 21 October 1993/Accepted 18 February 1994
I just discovered this article that could possibly shed some light on this issue.
I know I’m no PHD but it makes one curious.
The Max Plank Institute is a pretty respected organization so it’s not like I’m speaking out of my ear.
I googled: Hydrothermal vents in Lake Tanganyika, East African Rift system Pflumio, Catherine, Castro, Maryse, Boulegue, Jacques, Gente, Pascal, et al. Geology. Boulder: Jun 1993. Vol. 21, Iss. 6; pg. 499
And I came up with the above article from the Applied and Environmental Microbilogy journal.