Voyage 2 Sea-bed Ecology - Chatham Rise - Trip Reports
The first voyage of the Chatham- Challenger project was in August 2006 during which a series of multi-beam echo-sounder transects were completed across the Chatham Rise and Challenger Plateau. Based on the multi-beam results, the main aim of Voyage 2 is to collect information on the biodiversity and seafloor habitats on Chatham Rise with a view to comparing it to a similar data-set that will be collected on Voyage 3 to the Challenger Plateau.
Week 1: Getting deep-sea beasties to say “Cheese!”
The Voyage 2 team use a newly developed camera system to estimate deep ocean biodiversity and examine seafloor habitats.
The Deep Towed Imaging System, or DTIS, collects high-definition still and video images, and can be controlled by pre-programming the instrument or by sending electronic signals up and down the conducting cable. Importantly, low resolution video images are also relayed up this cable to the controller on the vessel so that biologists onboard can make real-time observations of the seabed creatures and their habitats.
Ideally, good images are obtained with DTIS “flying” at only 2-3m off the bottom, which is extremely difficult to do when there is a 2-3m swell!
After just one week, we have already obtained some impressive footage of animals that live in the muddy sediments of the Chatham Rise. These soft-sediment habitats cover the largest proportion of the world’s seafloor and are therefore important for maintaining marine biodiversity.
Download Voyage 2 Trip Report 1 (PDF 248kb)
Week 2: Sleds R Us
It’s been another busy week of sampling seabed habitats. Each day involves sampling at a number of sites that we think will characterise the biodiversity of different habitats on the rise. It is a 24-hour-a-day job, with the scientists and the ship’s crew and officers separated into separate watches, spread over two 12-hour shifts.
As well as DTIS, we are also using sleds and trawls that enable us to obtain actual samples of the animals we are observing.
The main sled we use looks a lot like a World War I tank. It has two steel runners, a 1m x 0.5 m-wide open mouth and a short mesh net for retaining the captured animals.
Steel tubes on the sides of the sled also allow us to collect sediment samples and to monitor when the sled is on the sea-floor.
When the sled is recovered, the sample is dumped onto the deck of the ship and is literally swarmed over by scientists eager to see what animals have been captured.
Download Voyage 2 Trip Report 2 (PDF 691kb)
Week 3: Boring Coring
For the last three weeks we have spent our time using various cameras and sleds to catch glimpses of every-day life in the Deep. Certainly, the photos and the biological specimens give us an appreciation of what the world is like in the cold, dark bottom waters of the Chatham Rise. From photographs, however, the sea-floor in soft-sediment environments can appear pretty monotonous.
Despite what you see in the seabed photographs, however, these habitats are far from boring. The multitude of burrows and trails tell us something about how animals live in the deep-sea.
Sea urchins move over extensive areas of sea-floor, chowing down on organic matter deposited in the sediments, and carnivorous gastropods “charge” after their prey (since speed is very relative in the deep-sea).
Some asteroids (sea stars) half-bury themselves in the sediment and ophiuroids (brittle stars) hang out in large burrows. Wherever there are even small pebbles of rock to cling to, sponges, corals and anemones happily live in soft-sediment environments, sometimes on the backs of other more moveable beasties
Download Voyage 2 Trip Report 3 (PDF 442kb)
Week 4: Everything, but the fish
As the second voyage of the Oceans 20/20 Chatham-Challenger Hydrographic, Biodiversity and Seabed Habitat project comes to a close, it is interesting to reflect on the voyage's achievements.
Over the course of four weeks we have travelled more than 6000km across the length and breadth of the Chatham Rise. We have collected biological and sediment samples from 293 stations at 99 sites. We have sieved more than 10 tonnes of sea floor material (rocks and sediment) to document nearly 3500 samples, some of which may be specimens that are new to science. Two hundred and seven fish specimens were also collected, but most were identified onboard and discarded. We have more than 110 hours worth of video tapes covering a range of sea-floor habitats from rocky seamounts to burrowed muddy sediments and just over 25,000 still images capturing the everyday life of the animals that inhabit the deep-sea.
The success of this voyage was made possible by the expert crew we had onboard Tangaroa who have gathered a large new data-set for New Zealand and overseas biologists to delve into.
Download Voyage 2 Trip Report 4 (PDF 888kb)