Microbiology of seawater
- The world’s oceans cover some 70 per cent of the Earth’s surface and have a salt content of 3.5 percent.
- The depth to which light can penetrate varies, but is limited to the first 100 meters.
- Compared to freshwater habitats, marine ecosystems show much less variability in both temperature and pH.
- A main issue in marine environments is that of pressure this increases progressively in deeper waters, and at 1000 meters reaches around 100 times normal atmospheric pressure.
- Increase in pressure is a decrease in temperature and nutrients.
- However, certain members of the Archaea have been isolated even from these extreme conditions.
- In contrast to terrestrial ecosystems, where plants are responsible for most of the energy fixation via photosynthesis, marine primary production is largely microbial,by the help of members of the phytoplankton.
- Protozoans and fungi that feed on the phytoplankton.
- Because of the high salt concentration of seawater, the bacteria that are typically found in such environments differ from those in freshwater.
- In the last decade or so, the presence of ultra microbacteria has been detected in marine ecosystems at relatively high densities; these are around one-tenth of the size of ‘normal’ bacteria.
- Marine bacteria are of halophilic.
- Anaerobic decomposing bacteria inhabit the benthic zone, carrying out reactions similar to those that occur in freshwater
- The profundal zone is largely free of microbial life.