Polar pecking order and biodiversity

New research into how biodiversity is generated and maintained in the seas surrounding hostile Polar Regions is reported in this month`s Proceedings of the Royal Society (Biological Sciences).

British Antarctic Survey biologist David Barnes studied `battles` between rock-dwelling marine organisms in shallow seas from the Poles to tropics to come up with a `league table` and a `polar pecking order` that lead to a greater understanding of extreme environments and how marine organisms may react to global change.

Barnes found that the battle for survival in the shallow seas surrounding the Polar Regions is much tougher than in the tropics. Not only must small aquatic animals (Bryozoa) compete for space to get food, they also have to contend with massive destruction of their habitat by icebergs and rough seas. However, by a strange twist of fate, these harsh conditions appear to increase biodiversity.

Barnes suggests that it is the very disturbance from ice and waves that ensures the long-term survival of these animals and increases biodiversity. He concludes that without a continuing battle against the extreme environment, polar aquatic animals at the top of the pecking order would out-compete other species and reduce biodiversity. Global climate change, however, could tip the balance in favour to those species at the top of the pecking order.

He says, `Small aquatic animals – bryozoans – that occur all over the world in very different environments were the ideal organism for this study. Although `a pecking order` exists in animals from elephant seals to bryozoans, until now we didn`t know what role this played in biodiversity. In tropical seas for example, battles between species often end in a draw and a wide variety species continue to live in this environment. Whilst in the Polar Regions one dominant species usually comes out on top. If it were not for the battering by ice the result could be monoculture.`