Hitchhiking …..

….. creatures from the deep.

One of the instrument platforms that we placed on the seabed a year ago was a mooring with a set of pressure sensors strung vertically up a cable, pulled vertical by quite a lot of flotation.

Flotation in the marine instrument world is quite readily recognisable as its generally a dayglo colour that is easy to see ….. yellow, fluorescent orange or pink etc.

Glass flotation is normally enclosed in yellow plastic hardhats to give it some protection – for example when it comes into contact with the side of a vessel.

Here is the sensor array having been released from the seabed, it is now at the surface awaiting collection.

It has multiple sets of flotation spread along its length – the challenge now is to catch it, and get in onboard in one piece.

To do this, the vessel comes along side, a grappling iron is thrown to catch the stray line, that is pulled around to the stern, and winched in.

Everyone waiting to pull it onto deck wears a safety harness which is tied to the deck so the there is no chance they can fall overboard, or at least if they do they are not going anywhere apart from dangling above the water surface.

Flotation and datalogger are hauled out of the water.

This section has got rather tangled up and will be untangled when safely on the deck.

Home safe and sound, we had five further seabed platforms to collect and these turned out to be an interesting set.

Many had hitchhikers – being in the shallower water several crabs had moved in to what they thought was a nice new home.

And everything came back covered in a gooey, black biological slime.

So in addition to scrubbing all the mud from the platforms in the much deeper water, this set will have to be scrubbed from top to bottom to get all the biological goo off, which is also very smelly.

A lovely job in the hot sun on deck.

However, we can do that while we are waiting for all the data to download – having been deployed for so long that is voluminous and this take a while.

We have a similar data problem – although it is a good problem to have – with the Azores platforms.

They are similarly recorded as they should have done and also have large datasets.

Hot of the press – one of the numerous earthquakes that they recorded.

So very positive signs from the Azores, we wonder what’s in the Congo dataset – did these instruments record the large-scale sediment slides – turbidites – that broke the internet cables in January?

We’ll have to wait a bit longer to answer that question, as large volume datasets not only take a long time to copy from instruments, and also back-up (multiple times), they also take a long time to process to find out what is in them!

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