Ecologists have long been fascinated by organisms living at extremes, be they microbes in boiling geysers, polar fish swimming in ice-laden seas or oryx living in the driest deserts. Studies of such organisms have revealed the remarkable flexibility of physiological systems in adapting to a range of what are, at least for us, formidably hostile environments. Recently we have come to recognise that life can be found in almost any habitat where water remains liquid, challenging our anthropocentric notions as to what constitutes a normal environment. This reassessment has come at a time when serious consideration is being given to not just contemplating the possibility of life beyond Earth, but actually going there to look. The time is clearly ripe for a thorough and comprehensive review of our knowledge of life in extreme environments, and this is precisely what this volume is aimed at providing.
The book emanates from the European Commission Framework 7 Coordination Action for Research Activities on Life in Extreme Environments (CAREX). It comprises 27 chapters with a strongly international authorship: the 60 authors come from 14 countries. Although a strong European bias is inevitable given the funding from CAREX, there are notable contributions from the US, India, Australia, New Zealand and South Africa.
The volume opens with two introductory chapters. The first tackles the vexed question of what precisely is an extreme environment, and the second takes a historical perspective, pointing out that what we might regard as an extreme environment now (for example anoxia) was once the norm. The arrangement of the remainder of the book is conventional with individual chapters are assigned to different environments. There is a degree of overlap in subject areas between some chapters, for example those dealing with polar terrestrial habitats, cold alpine regions, and polar deserts; and again there are individual chapters dealing with hydrothermal vents, the deep-sea, and high-pressure environments. In general, however, these chapters complement each other rather than duplicating content, and the book gains overall from the interesting differences in perspective. For example only the chapter on high pressure deals with physiological aspects, the other two concentrate instead on ecological and life-history aspects.
The chapter on polar marine ecosystems emphasises the contrasts as well as the similarities between the two polar regions, and placing nice emphasis on processes such as disturbance. Sea ice is a key feature of polar marine systems and is given an individual chapter. Polar terrestrial environments are given a thorough review and the cold alpine regions are set in the context of the cryosphere as a whole, showing that in terms of area they are more important than the polar regions, and emphasising the importance of atmospheric dispersal as a linking process. A short chapter on subglacial lakes is inevitably somewhat speculative, but does provide a useful synthesis of knowledge before any of these lakes are sampled and analysed.
Other environments covered include terrestrial hydrothermal areas, caves, acidic, alkaline and hypersaline lakes, and habitats exhibiting anoxia and high UV. There is a short discussion of climate change, and also of anthropogenic extreme environments, and the volume concludes with discussions of possible technological developments based on extremophile phsyiologies, and the relevance of extreme environments of Earth for life elsewhere in the universe. The chapters have been well edited, and are generally well up to date. For example the discussion of diversity in deep-sea benthos includes the latest (2010) important data from the Census of Marine Life. The book is produced to a very high standard, and includes a nice selection of images, many in colour.
When extreme environments are pulled together into a single volume such as this, a number of interesting themes emerge. Extreme environments are more varied, more extensive than might be expected. And they can be highly productive, with a rich and diverse biota.
Lastly, praise is due to the editor, Elanor Bell. Not only has she collated and edited an impressive body of authors, and managed to get the volume out in a timely manner, she is lead author on four of the chapters and co-author on a further three. This is an excellent volume that should stand as the definitive review of the ecology of extreme environments for many years. I enjoyed the book greatly, and it will be much used in the coming years.
