‘A given environment, where one or more parameters show values permanently close to lower or upper limits known for life, may be considered as an ‘extreme environment.’ European Science Foundation
From the deepest seafloor to the highest mountain, from the hottest region to the cold Antarctic plateau, environments labelled as extreme are numerous on Earth and they present a wide variety of features and characteristics. The life processes occurring within these environments are equally diverse, not only depending on stress factors (e.g. temperature, pressure, pH and chemicals), but also on the type of life forms, ranging from microbes to higher species.
‘How is life limited by and has adapted to extreme external biotic and abiotic factors?’
Polar regions, outer space or deep-sea, these environments have always triggered human curiosity and their exploration has fascinated not only scientists but also the general public. However, they have been explored or sampled only very recently, mainly because of earlier technical limitation
For most environmental parameters constraining life, specific limits have been established. For example, the highest temperature allowing the complete life cycle of an organism (the archaeon Pyrolobus fumarii) is 113°C, the lowest is -18°C. A given environment, where one or more parameters show values permanently close to the lower or upper limits known for life may be considered as an ‘extreme environment’.
Coping with extreme conditions, microbes, plants and animals have demonstrated the ability to adapt and metabolise under high environmental stress. Relying on specific and complicated mechanisms, some organisms even require such conditions to live and evolve.
A few typical extreme environments can be identified. This Unit of work will focus on two extreme environments;
The Deep ocean and Polar Regions