The discovery of deep sea corals on the Hebrides Terrace Seamount by the Changing Oceans Expedition has just been published in Nature Scientific Reports and featured on the BBC.
The new populations of deep-sea corals were discovered growing on
the slopes of the UK’s highest underwater mountain – a site recently added to
the list of Scotland’s new Marine Protected Areas.
Standing at 1400 m above the surrounding seafloor, the Hebrides
Terrace Seamount is the UK’s highest underwater mountain (Beinn Nevis is 1344 m
above sea level).
The deep-sea corals were discovered by a robot sub during the
first-ever visual survey of the steep, sloping flanks of the Hebrides Terrace Seamount,
an extinct, subsea volcano, during the Changing Oceans Expedition
The corals support rich communities of other species and play a
critical role in the life history of species that range far beyond the UK’s
shores, such as threatened deep-sea skates which lay their eggs on them.
Researchers were surprised
to find the corals growing at such depths, in seawater that is less hospitable
than shallower water such as Rockall Bank where some of the best-known cold-water
coral reef systems in the world are found.
At the seamount depths, the seawater is naturally more corrosive
to coral skeletons and as ever- greater levels of carbon dioxide are released
into the atmosphere, the oceans of the world are becoming more acidic.
Therefore the corals discovered during this survey may provide an
important warning gauge of climate change, because they are already growing
close to their limits.
If the water gets any more corrosive as the oceans become more
acidic, then the parts of these deep-sea coral reefs that support so many other
species will dissolve away.
The knock-on impact of ocean acidification on already-threatened
and little known deep-water species such as the deep-water skate, could be
catastrophic.
Because ocean ecosystems are under pressure from ocean
acidification and other aspects of global climate change, Marine Protected
Areas will become a vital way of conserving fragile ecosystems like those on
the Hebrides Terrace Seamount.
The international survey team was led by Prof J Murray Roberts of
Heriot-Watt University, aboard the RRS James Cook. Supplementary ship time funding for the
Hebrides Terrace Seamount ROV survey was received from the Joint Nature
Conservation Committee with the agreement of NERC.
Speaking about the discoveries made during the survey, Prof Roberts,
Professor of Marine Biology at Heriot-Watt University, said “These were some of
the most exciting surveys we’ve ever carried out at sea.
“We had spent almost a month at sea before we surveyed the
Hebrides Terrace Seamount and it was so different from the other sites we
examined.
“Now we need to get back to these sites to work out how these
corals are able to survive in these harsh conditions.
“In the meantime it’s very promising to see this important place
included as one of Scotland’s Marine Protected Areas.”
Their findings are reported in an
academic paper: Henry, L.-A. Et al. Environmental variability and biodiversity
of megabenthos on the Hebrides Terrace Seamount (Northeast Atlantic). Sci. Rep. 4, 5589; DOI:10.1038/srep05589 (2014)
recently published online in Scientific Reports www.nature.com/scientificreports
