Life abounds deep in the Kaikoura Canyon

By Rebecca McLeod 27/10/2010 4


Why are we humans trying to get to Mars when we still have so much exploring to do here on lowly old Earth?! Perhaps we know enough about our seas already? Well, recent findings of scientists from NIWA and further afield suggest otherwise. In a paper in the prestigious journal Proceedings of the Royal Society B, these marine scientists report an incredible amount of life at the bottom of the Kaikoura Canyon – an undersea canyon just off the east coast of the South Island of New Zealand.

Kaikoura Canyon plunges into the deep sea just meters off the Kaikoura Coast. Map: NIWA ADD ADDRESS
Kaikoura Canyon plunges into the deep sea just meters off the Kaikoura Coast. Map: NIWA (http://www.niwa.co.nz/our-science/oceans/bathymetry)

Using a combination of grab samples of the seafloor sediment, and footage from cameras towed along the bottom of the canyon, the scientific team were able to measure the number of invertebrates (worms, sea cucumbers, sea urchins etc.) living in the muddy sediment of the canyon at depths of over 1 kilometer below sea level. They also measured the total weight of these invertebrate communities and found them to exceed by 100 times the highest invertebrate biomass ever recorded in other deep sea environments worldwide (excluding the unusual hydrothermal vent/black smoker communities).

The science team were able to tap into archived data from historical fish trawls to get information about the number of fish living in the canyon, and again they found the site to be incredibly “productive”, with extraordinary numbers of (creepy-looking) rattail fish down there – no doubt feeding on all those tasty invertebrates in the mud. And, just a hunch here, but I reckon this abundance of fish could well be one of the reasons sperm whales just can’t get enough of the Kaikoura region.

Fat Freddy's Drop trombone player gets a little intimate with a rattail. Photo: Phil Freeman for scoop.co.nz
Amazing what you find on the internet when you type in "rattail" - a picture of Fat Freddy's Drop trombone player Ho-Pepa getting a little intimate with one. Photo: Phil Freeman for www.scoop.co.nz

So why do so many creatures congregate in such a deep dark place? The scientists put it down to there being a huge input of food from the water column above and from coastal areas in shallower water (think plant material from land, kelp etc.) – all this material settles into the canyon as there isn’t a whole lot of water movement going on.

All of this new information raises the status of the Kaikoura Canyon to “one of the most productive benthic habitats known for the deep sea”. And it seems that given there are at least 660 such canyon habitats worldwide, and most of them are yet to be scientifically explored, we have a lot more to learn before we board that space shuttle for Mars.

Reference: F.C. De Leo, C.R. Smith, A.A. Rowden, D.A. Bowden and M.R. Clark (2010) Submarine canyons: hotspots of benthic biomass and productivity in the deep sea. Proceedings of the Royal Society B 277: 2783-2792

Related posts: Now we can all be deep sea explorers


4 Responses to “Life abounds deep in the Kaikoura Canyon”

  • Well, some of us do both – the lab I’m in works on hydrothermal vent organisms and astrobiology. In fact, a lot of people do, because deep-sea hydrothermal vents are good analogues for potential habitats on places like Mars or Europa. It doesn’t have to be either/or!

  • Ah yes, good point Lucy! Sounds like such a cool area of research – so what sorts of things are being researched in your lab at the moment?

  • Microbe-mineral interactions with iron reducers and the bioenergetics of methanogens and other thermophiles, mostly, from vents off the west coast of the US. Three of us are about to head off this weekend to a hydrothermal vent research conference, where there will be a bunch of astrobiologists as well. Should be really interesting!

  • Fascinating stuff, sounds like a great conference! I have been involved in research in chemosynthetic communities in recent years too – in the NZ fjords, where there is very high input of organic matter (forest and marine algae) to the seafloor, we find a lot of chemo invertebrates. No where near as high a biomass as most vent communities, but definitely supporting the wider food web in the fjords – all the way up to predatory fishes. These kinds of systems are being found all over the place! Great stuff.