Even in the dark abyss of the deep ocean animal communities can undergo rapid, widespread and radical changes. Scientists at the National Oceanography Centre are at the forefront of monitoring these changes and understanding the mechanisms responsible. Their latest research is published in a special issue of the journal Deep Sea Research II.
We often think of the deep ocean floor as stable, relatively unvarying environment untroubled by surface climate conditions. But long-term monitoring has shown that animal communities living at great depth on the seafloor can change radically over remarkably short periods, and that these events are ultimately driven by climate.
Such faunal changes are exemplified by the 'Amperima Event' the sudden mass occurrence of the sea cucumber (holothurian) Amperima rosea recorded on the Porcupine Abyssal Plain (PAP) situated off the southwest coast of Ireland in the northeast Atlantic. Communities of animals living on the seabed there at depths of nearly 5000 metres have been monitored from 1989 to the present day.
A major change occurred in the PAP community between 1996 and 1999 involving a number of animal groups, including sea anemones, segmented worms, sea spiders, sea squirts, brittle stars, and sea cucumbers, all of which increased in abundance.
However, the population explosion in the sea cucumber Amperima rosea (hereafter Amperima) was particularly striking thus the 'Amperima Event'. Before 1996 the sea cucumber was found in only ones or twos. They were very rare. But by 1999, the sea cucumber reached such high densities that if you were able to walk on the deep seafloor, you would have difficulty in avoiding squashing them flat.
Dr David Billet and his colleagues showed that the increase abundance and dominance of Amperima occurred over a very wide area, greater than the size of the UK. Changes are also apparent in the abundance of other animals livin
|Contact: Dr. Rory Howlett|
National Oceanography Centre, Southampton (UK)