Biology Reference
In-Depth Information
Figure 15:
Microbial loop and the role of virioplankton in causing the consequential carbon and nutrient cycling in the ocean
ecosystem. Picture courtesy U.S. Department of Energy Genomic Science program and the website http://genomicscience.
energy.gov.
Color image of this figure appears in the color plate section at the end of the topic.
diverse (Moore
et al
., 1998). These two ecotypes also exhibit differences in nitrogen and phosphorus
utilization and copper (Mann
et al
., 2002) and also phage sensitivity (Sullivan
et al
., 2003). As already
mentioned, marine
Synechococcus
is represented by many strains that are grouped into MC-A and
MC-B. The distribution of these strains in relation to depth, salinity and nutrient concentrations has
been investigated in detail.
Prochlorococcus
seems to be abundant than
Synechococcus
, as the former
accounted to nearly 31% of the bacteria-sized organisms in the oligotrophic waters of North Pacifi c
(Waterbury
et
al
., 1979; Campbell
et al
., 1994). It was only through the use of fl ow cytometry and
epifl uorescence microscopy that
Prochlorococcus
emerged as the most important component of the
marine phytoplankton. These two cyanobacteria are suggested to fi x as much as 20-80% of the
carbon in these environments (Joint and Pomroy, 1983; Li
et al
., 1983; Waterbury
et al
., 1986; Liu
et
al
., 1997). Although the existence of VLPs in the cells of marine phytoplankton was demonstrated
