New Zealand is one of the few places in the world where at least four types of chemosynthetic habitats occur in close proximity, allowing scientists to address key questions about the patterns of biological distribution that cannot be addressed elsewhere.

Onboard NIWA’s deepwater research vessel Tangaroa, the 21-member expedition – led by scientists from WHOI, NIWA, the Scripps Institution of Oceanography, and the University of Hawaii at Manoa (UH) – has spent two weeks exploring eight cold seep sites and other ‘chemosynthetic’ ecosystems on the continental slope to the east of the North Island, lying at depths of 750–1050 m.

The team pinpointed potential seep sites using sophisticated sonar to map seafloor topography and substrate and to detect plumes of methane-enriched water. The scientists then lowered a towed video and still camera system over each site to identify seep organisms and the extent of the seafloor they covered.

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With the live video feed, the scientists observed 30–40 cm long tube worms emerging from beneath limestone boulders and slabs lying at the core of the seeps. Around the rocks were patches of blackened sediment and pockets of white bacterial mats.  Most sites also had extensive shell beds consisting of live and dead shells of various types of clams and mussels. These were fringed with stands of another type of deep-sea tube worm that is also gutless and relies on symbiotic bacteria for its nutrition. Corals and, at two of the sites, numerous sponges, were also observed.