Day 12: Hidden creatures of the deep!

Today’s blog is written by Anne from the University of Hull, about the teeny tiny invisible creatures of the deep.

Look at the pictures of the amazing deep sea coral reef  and think about what’s living there. What mainly comes to mind? Coral? Fish? Sea urchins? Crabs? I bet you’re not thinking about the microbes, but that’s exactly what Geoff and I do! When we see a scene like that we’re wondering what bacteria, fungi and viruses are present there and what they’re doing. Just like humans have microbes all over their insides and outsides, the same is also true of corals and other marine creatures. These microscopic organisms can affect their hosts in a number of ways, ranging from helping to keep them healthy (think yakult!) to causing disease. However, we know very little about the identity or function of microbes in these deep, cold water coral reefs, largely because they’re so difficult to study.

The sampler on ROV
The main problems are that the microbes on the coral aren’t always very well stuck to them and the sea is full of other microorganisms so if coral is just pulled up to the surface, many of the microbes that live on it will be washed off and replaced by others. To get around this problem Geoff has designed and built a special sampler (see photo). This consists of six canisters with lids held on by super strong magnets which we fix to the remotely operated vehicle (ROV) and send down to the seabed. Once there, the right robotic arm of the ROV removes the lid of one of the canisters whilst the left arm picks up the ‘slurp gun’- a device like a really strong vacuum cleaner. It then uses this to hoover up a few little pieces of coral and puts them in the canister. The right arm then puts the lid back on and seals it tightly shut. By encasing the coral samples like this, we protect them from contamination so when the ROV returns to the surface, the microbes are still on them just as they were when they were originally 800 metres underwater. A huge amount of time and effort was put into designing and building this sampler and before this cruise it had never been tested under such extreme conditions, so the first dive was pretty nerve racking! It worked like a dream though and watching the ROV operators getting such great samples for us in such a technologically advanced way has been an amazing experience!
Geoff and Anne prepare samples

Once the ROV’s back at the surface, we remove the canisters and begin the challenging task of studying the microbes they contain. Classically, people have done this sort of work by growing them in petri dishes and tubes but this approach can lead to a very biased view of what was actually originally present as not all micro-organisms will thrive in such artificial conditions. For this reason we use techniques that don’t rely on growing anything at all. Just like the police use DNA evidence to see who was present at the scene of a crime, we use very similar techniques to find out which bacteria were on the coral.

Preserved coral polyp
We’ll also use a method called fluorescent in situ hybridisation (FISH) which uses special chemical probes which glow when they bind to bacteria so we can look at the coral under a microscope to pin-point their exact location. Unfortunately these techniques take a long time and require very expensive specialist equipment that we don’t have on the boat. This means that for now we’re spending our time preserving the corals so we can look at them once we’re back on dry land and finally understand more about these often ignored but very important little organisms!
Anne of Team Microbe
Geoff of Team Microbe