Crocosphaera watsonii (strain
WH8501) belongs to a novel genus of marine unicellular (2.5-6 µm
dia.) diazotrophic cyanobacteria that occur in ocean waters warmer
than 24?C. It has been isolated from offshore
open ocean oligotrophic waters in the western tropical Atlantic and from
the tropical Pacific oceans where it may achieve cell densities exceeding
1,000 cells per milliliter within the euphotic zone. The size, abundance
and rapid growth rate (i.e., 35 hour doubling time at 30?C) of Crocosphaera
WH8501 indicate that this diazotrophic cyanobacterium is capable of contributing
significantly to oceanic carbon and nitrogen budgets in the tropical
regions of the world's oceans.
Photo credits: Zehr, J.
P., J. B. Waterbury, P. J. Turner, J. P. Montoya, E. Omoregie,
G. F. Steward, A. Hansen, and D. M. Karl.