Deep realm research beyond the Census of Marine Life: A trans-pacific road map

The ChEss project of the Census of Marine Life (2002-2010) helped foster internationally-coordinated studies worldwide focusing on exploration for, and characterization of new deep-sea chemosynthetic ecosystem sites. That work advanced our understanding of the nature of factors controlling the biogeography and biodiversity of these ecosystems in four geographic locations: the Atlantic Equatorial Belt, the New Zealand region, the Polar Oceans of the Arctic and Antarctic and the SE Pacific close to the Chile Triple Junction. Major discoveries in the Atlantic included the location of the deepest vents (found on the ultraslow spreading Mid-Cayman Rise) and the hottest vents (found on the Southern Mid-Atlantic Ridge). Furthermore, it was shown that the major fracture zones of the Mid-Atlantic Ridge do not create barriers for the dispersal of a number of vent species but may act as conduits of dispersal for cold-seep species that have been shown to be amphi-Atlantic. The more remote South Pacific region received comparatively less attention, although In the New Zealand region, 10 new cold-seep sites were discovered along the Hikurangi margin while off Chile - a unique place on Earth where an active ridge is being subducted beneath a continental margin - recent exploration provided evidence for two separate hydrothermal sources, one of which may be sediment hosted, along with a methane-rich cold-seep area. Based on our 8 years of investigation of deep-water chemosynthetic ecosystems, worldwide, we are now uniquely well placed to recommend a range of future directions. Highest priorities, from this perspective, should include a concerted effort to link with other scientists active in the Deep Ocean Realm and coordinate a major investigation of the South Pacific Ocean - the largest contiguous habitat for life within Earth's biosphere, but also the world's least investigated deep-ocean basin.