Physiological adaptations to extreme pressures: the implications for palaeoecology

Abstract

ABSTRACTPresent-day organisms have colonised two distinct high pressure environments: the deep sea and oil well and other crustal fluids. In the former, pressures attain 100 MPa and temperatures are generally less than 4°C. In the latter, the temperatures are high, up to 150°C, and occur in combination with pressures of up to 50 MPa. The high temperature is close to the limit of thermal stability of the macromolecules essential for life. The adaptation of present-day marine organisms to high pressure is known to involve modifications to their cell membrane lipids and subtle changes in both structural proteins and enzymes. There is no reason to suppose that they are close to the maximum pressure to which they could adapt and higher pressures could have been colonised in the geological past. The existence of “marker” compounds, characteristic of high pressure organisms, is discussed, and the possibility that isotope ratios are distorted by metabolic processes at high pressure is raised.