Cruise News

 
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 >>

Crozet worm blog
18/12/05

by Adrian Glover

What am I doing in the middle of the Southern Ocean, 1000 miles from anywhere, collecting worms? And in particular, why should anyone care about worms from the Crozet Islands of all places? Despite the occasional few minutes of self-doubt, lying awake at night in my cabin aboard RRS Discovery, I can, I think, answer this question. For one thing, it turns out that worms are rather more common than you might think. The earth’s surface is over 60% ocean, and take any sample of the seabed of that ocean – with a bucket, trawl, or dredge – and the chances are you will bring up a large handful of worms, especially polychaetes – marine segmented worms which are known for their ‘hairy’ appearance. These things are so dominant in the marine realm, that an alien from outer space, randomly sub-sampling planet Earth for life, would most likely bring up a load of polychaetes in their first samples.

The ‘worm’ lab…
The ‘worm’ lab…

So they are common, but what do they do? And most importantly, why should anyone care? This question can be answered in two ways. Firstly, because the abyssal plains (such as those around the Crozet Islands) are so remote and difficult to sample, we have really very little knowledge of this group of organisms. So, for the most part, we don’t know what they do. But the research that has been carried out shows that they are incredibly biodiverse, with perhaps thousands, even millions of undescribed species in the deep sea. The first step in understanding an ecosystem is to describe the animals that live there, and to compare these new species with those we have found from elsewhere. This gives an idea of the ‘community’ of animals living in this region, and how similar – or different – it is to other places that we know much better. Describing these new species also allows us to place them in their evolutionary context, on the ‘tree of life’, which helps us to understand how and why these things evolved in the first place.

Somewhere in this bucket is a worm that is going to change the world!
Somewhere in this bucket is a worm that is going to change the world!

The second part is perhaps more complicated. What function do these worms perform? Worms that live on abyssal plains, 4000m from the surface of the ocean, are detritivores, consuming ‘detritus’ (dead organic-rich material) that has fallen from the surface layers of the ocean, where photosynthesis takes place. Hence they perform the rather important function of recycling organic material at the seafloor. The abundance and community structure of the worms, can help us to understand the processes occurring in the ocean above. We can measure various wormy parameters (e.g. how abundant, how many species, what function they perform) and compare this with what we know about the biology of the ocean above them.

The USNEL spade box core. Advanced ‘bucket and spade’ technology.
The USNEL spade box core. Advanced ‘bucket and spade’ technology.

So that is the reason I am here. There are worms down there, and somebody needs to sort them out. One of the other cool things about polychaetes is that they are actually quite pretty. So here are some pictures of polychaetes (taken down the microscope) from our recent trawl and box core samples at station M5:

A large scale-worm from the abyssal plains of Crozet.
A large scale-worm from the abyssal plains of Crozet.
A cirratulid polychaete brought up in a box core.
A cirratulid polychaete brought up in a box core.
This large, onuphid polychaete is abundant in our trawls and lives in muddy tubes.
This large, onuphid polychaete is abundant in our trawls and lives in muddy tubes.
Click on the pictures for a larger version. Opens in new window/tab
 
Last updated 4/02/08