Stations 40 and 42, Oceans Survey 20/20 Chatham /Challenger expedition
How do we know what lives on the soft bottom of the Chatham Rise?
Capturing photos using our Deep Towed Imaging System DTIS reveals some but not all of the critters that call it their home. Taking physical samples (using trawls, dredges or corers) is still sometimes important to ‘ground truth’ what we see in the stills. And in most cases, these specimens can be matched up with the DTIS images and allow a confident identification in most cases which allows for less deployment of sampling gear, which in turns disturbs the seafloor less. See if you can spot the critters on the seafloor and whether you recognise any on deck!
Here is an example of the seafloor from station 40, around 480 m deep, of the 2007 Chatham/Challenger expedition on the southwestern flank of the Chatham Rise. In high-resolution you can see a few little critters on and in the soft sediment, such as the cup corals and the starfish. [Photos: DTIS/ Oceans Survey 20/20 Chatham-Challenger expedition]
A short tow later, station 42 of the 2007 Chatham/Challenger expedition across the same area reveals what we have (and have not) been seeing on the DTIS images. We collected a few larger starfish, cup corals and soft corals, quill worms, snails and hermit crabs and a suite of smaller critters. In all 50 different species were collected from a short tow on this site! Most of these would be invisible to the camera.
The unique single-polyp soft coral Taiaroa tauhou is only known from New Zealand and it is usually half-buried in the soft sediments, spot the little crown of the tentacles. We featured this fascinating creature as CotW #58. [Photo: Owen Anderson, NIWA/Oceans Survey 20/20 Chatham-Challenger expedition]
The cup coral Flabellum, can be seen half submerged or on top of the soft sediment. We featured these ‘dentures of the sea’ as a CotW #6. [Photo: Peter Marriott; Ocean Survey 20/20 Bay of Islands Coastal Biodiversity, Sediment and Seabed Habitat Project]
The quill worms, Hyalinoecia longibranchiata, are incredibly abundant in these habitats, they are large carnivorous or scavenging worms who build their own tube for protection. A Critter of the Week on these will be coming your way shortly. [Photo: NIWA/Oceans Survey 20/20 Chatham-Challenger expedition]
