JC010: Mud volcanoes and submarine canyons


Cruise diary

Day 9: Friday 29 June 2007
Position: 38°14.18N 09°23.18W (Google Earth reference: 39 34’3”N 10 18’11”W)
Weather: Sunny

Richard writes:

"Yesterday I got talking to more of the ship’s crew. It was great to hear recollections about their lives at sea, and they had lots of hilarious stories to tell. They all asked me if I was thinking about a career change now that I have been on board for over a week! Over the next week Tina and myself aim to talk to more of them and find out exactly how they ended up in their jobs – maybe you can follow in their footsteps?

I have to say before I came onboard I thought that some people may be a bit ‘iffy’ about teachers taking up space on the RRS James Cook. It is after all a chance that only a tiny amount of people will ever have. In fact, it is quite the opposite and everyone seems to be really supportive of us and the reasons we are here. Jez, an operations manager, was talking to me about the whole Classroom@Sea project. He said he thought it was brilliant and that it would be a great opportunity to get lots of pupils involved, not only in the Science side of things, but also from an operational point of view – maintaining equipment, crane operations, technical support and much more. If it weren’t for the crew, none of this groundbreaking science would be able to take place – the ship could not have left Southampton!

Anyway, if you are interested in careers at sea, keep checking the website for further developments. Don’t forget, if you want to know more, you can always drop us a line using the ‘ask a question’ section. There are plenty of experts, in all sorts of fields, on board so you can expect a pretty insightful answer!

Today we:
Carried out a geological reconnaissance of the site of a landslide taking some cores, examples of the rocks we found and carrying out a swath survey of the topography.

Operations in full swing

Heavy lifting - hard hat zone!

Nothing to see here!

Tina writes:

"This is what I was taught at school:

‘Big bugs have little bugs
Upon their backs to bite ‘em.
Little bugs have littler bugs.
And so, ad infinitum’

When I looked carefully at this picture I spotted – bugs? – and were they there to ‘bite’em’?  If they were not there to ‘bite ‘em’ what were they doing?  Hitching a lift?  Feeding on something that was on the surface of the Sea Spider? 

So I started on a search to find out. The first thing I learnt was that the ‘bugs’ were probably amphipods.  Amphipods have sharp powerful jaws that slice through flesh, dead flesh.  They are scavengers.  The Sea Spider is most definitely alive so these amphipods may be just hitching a ride until they sense their next meal.  Or they may be trying to stay out of the fine silt on the bottom of the sea floor.

Understanding the different species that live in the deep oceans is vital if you are going to understanding the complex ecosystems. Here are some of the deep-sea fauna we came across in yesterdays ROV reconnaissance:

The scientists on board easily named most of these species, but what happens when you come across something you do not recognise?  How do you work out what it feeds on?

You can capture one and look at find out what it has eaten. BUT most deep-sea creatures are opportunistic feeders and this may not give the full picture.

To find out about the feeding habits of the animal you are studying you can investigate the different isotopes for elements like carbon and nitrogen in the animal you are studying. 

Try to follow the science:

Isotopes are different forms of the same element. So Carbon exists as different isotopes carbon-13 (heavy) and carbon-12 (lighter); carbon-12 is the most common and carbon-13 less common.  In fact naturally for every one atom of carbon-13 you find 99 atoms of carbon-12.

Processes in plants and animals select against  the carbon-13.  So a plant photosynthesising will have less carbon-13 in it and so will be isotopically light.  So when an animal at the bottom of the ocean feeds on something that has fallen through the water column (as marine snow) from the ocean surface it also becomes isotopically light.

When animals eat they then convert what they eat into energy.  BUT respiration in living things selects against carbon-13, and so the carbon-13 stays in the body.  So, relative to carbon-12 the carbon-13 accumulates.  And as you move higher up the food chain more carbon-13 accumulates.  So marine animals that only feed on other marine animals tend to be isotopically heavy. 

Carbon isotopes are used to work out if an animal has fed on something from the surface (isotopically light) or from food sources in deeper water (isotopically heavy).

Nitrogen is also used in the same way - you can get nitrogen-14 (light) and nitrogen-15 (heavy). This time, when animals excrete nitrogen they select against nitrogen-15 and so nitrogen-15 accumulates in the body becoming isotopically heavy.

Scientists know how much each stage of the food chain will accumulate nitrogen-15 and so can work out how far up the food chain an organism is.

Of course, it is far more complex than this but if you have followed this you are doing well - students study this at university.



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