Marine microbial ecology

Marine microbes - single celled plants and animals (phytoplankton and protozoa), bacteria and viruses - comprise most of the living matter in the sea. Photosynthesis by phytoplankton takes up CO2, producing the food that supports, directly or indirectly, the wealth of marine life for which Antarctica is renowned. However, only a small proportion of the carbon taken up flows directly on to organisms such as krill, fish and whales. Most of this carbon is cycled by microorganisms in the so-called microbial loop.

Marine microbes also have major effects on the world's climate. By absorbing carbon dioxide, they contribute to the uptake of CO2 from the atmosphere, thereby moderating the global Greenhouse Effect. The Southern Ocean is one of the world's important 'sinks' where carbon is transported to the deep ocean by sinking particles. Some microorganisms also produce chemicals which, when ventilated to the atmosphere, form aerosol particles that can trigger the formation of clouds.

Scanning electron micrograph (SEM) of the chitinous lorica (outer shell) of a tintinnid
Image: Fiona Scott
The urn-shaped lorica (outer shell) of this tintinid is 35 micrometers long, composed of hard, chitinous material, and has a surface sculptured with cup-shaped depressions.
SEM of the dinoflagellate Protoperidinium latistriatum
Image: Fiona Scott
Protoperidinium latistriatum is a pentagonal dinoflagellate cell, about 30 micrometers long. It has an outer shell made of polysaccharide armoured plates each separated by adistinct, zipper-like growth zone.
SEM of Triparma columaceae subspecies alata, a member of the Parmales
Image: Fiona Scott
Triparma columaceae subspecies alata is about 3 micrometers across, roughly spherical in shape but pointed towards both top and base. The outer coating of the cell is made up of a small number of striated, silica plates, each having a wing-like projection.
SEM of the silica skeleton of the silicoflagellate, Dictyocha speculum
Image: Fiona Scott
The silicon skeleton of Dictyocha speculum is a hexagonal ring with a long spine projecting from each corner.
This page was last modified on 12 August 2010.