Sounds from Iceland

By Clare Embling

Image credit Mike Hood

It’s great to be back on the Extended Ellet Line – the last time I came on this survey was 10 years ago on the RRS Charles Darwin. Then and now I was towing a hydrophone behind the ship (an underwater microphone) to listen for whales, dolphins and porpoises (cetaceans). Then it was for my PhD investigating the distribution and habitat use of cetaceans off the west coast of Scotland. This time I bring my PhD student (Leah Trigg) who is looking at the impact of shipping noise on marine mammals.

I use sound as a tool to find out where cetaceans are in the oceans. Out here in the deep blue sea far from land, the sea is often rough, and cetaceans hard to spot, so using hydrophones becomes a much better way of finding them. Our hydrophone is towed 350m behind the ship to distance it from the ship noise, we can hear most cetaceans that vocalise except for the very low sounds of baleen whales (they ‘moan’ below our range of hearing, and below the range of our hydrophone < 100Hz). It’s a shame because we saw a fin whale on our first day out of port, in glassy calm seas (never seen one out here before because the sea conditions aren’t usually good enough!) – it would have been great to be able to hear it too!

Here’s an example of what we’ve heard this trip – it’s a fantastic recording of some pilot whales. If you listen carefully you should be able to hear their whistles (used for communicating between each other – their version of language), echolocation clicks (used for finding their fish or squid food), but also you’ll be able to hear the pings of the ship’s echosounder used to find the bottom in this very deep patch of ocean, the rotating of the propeller, and maybe even some water noise from the waves going over the hydrophone.

 

A patchwork ocean

By Stefan Gary

Yesterday’s blog mentioned that the glider Eltanin had been trapped in an ocean eddy. Ocean waters can vary dramatically from place to place and eddies are evidence of the mixing between waters. The result of these eddies is an ever-changing patchwork ocean, an example of which is shown in the image below. The outlines of Ireland and Scotland are in the lower right corner and the glider recovery location is marked by the black circle.

The sea surface temperature map shown here is supplied to us thanks to the NERC Earth Observation Data Acquisition and Analysis Service (NEODAAS). This map, constructed from near-real time observations, helps us understand the large-scale ocean conditions surrounding us while we are at sea.

We are currently just south of Iceland and have successfully completed 4 full-depth casts for collecting water samples and data from sensors. Conditions are good and we’re making good progress. Unfortunately, it wasn’t clear enough to catch sight of Iceland despite the fact that our mobile phones caught signal!

Glider recovered!

By Ashlie McIvor and James Coogan

Photo Credits: Winnie Courtene-Jones and James Coogan

The Extended Ellett Line cruise continued with another action packed day of discovery! It all kicked off with a fire drill at 15:30 and afterward we headed to the forecastle deck for hose training. Everyone had a fun turn of blasting water over the edge of the ship. With that done and dusted we progressed into glider recovery mode.

The poorly glider, Eltanin, had battery issues and was caught in a swirling ocean eddy, travelling in circles like a drunken sailor! As we approached, honing in on the position, it was all eyes on deck to spot the bright yellow casing bobbing among the rolling waves. Once spotted, the cauldron of excitement just about boiled over and the spectator sport began in earnest. We huddled on the decks above the work deck, and waited, cameras trained.

Retrieving her was a little more challenging. The crew assembled with a “recovery lasso” mounted on a long stick attempting to snare the disobedient robot. Multiple attempts were made in vain before the DIY extend-o-broom was brought out, consisting of a long stick with a broom duct taped to the end. The glider made one last bid for freedom before the combined efforts of extend-o-broom and recovery lasso managed to hook the tail and hoist her up. Eltanin was then stretchered off and treated to a shower after her long voyage. Well deserved!

The Adventure Begins

Jonathan Tinker Met Office Hadley Centre

Image credit: Elizabeth Comer University of Southampton, National Oceanography Centre.

I’m fairly new to research cruises, so thought I might write a blog entry to give a fresh perspective.

So it’s now day two on the Cruise, or Julian Day 160, as I’m starting to get used to referring to it as. We sailed out of Glasgow yesterday, with lovely conditions, having seen porpoises, seals, a submarine and several whales. Yesterday was mainly about getting into the swing of the cruise, safety drills, starting to get everything ready for research once we get on site.

We had our first practice instrument deployment (the “shake-down”) this morning (red circle on the map). We had planned to do this at the continental shelf break, north of Ireland, where the water first drops to 500m. However, this would have been in the middle of the night so we planned our practice run for after breakfast, in about 2000m of water. This involved lowering a rig, with a number of instruments and 24 water bottles (“rosette sampler”) to take water samples. The instruments measure a number of things, including the temperature and salinity of the water (via the CTD), chlorophyll, oxygen concentration etc. It’s interesting lowering expensive equipment off the side of the ship! The rig was winched off the deck by the crane, and then lowered over the side to 500 m. On the way back up, the water bottles were closed (“fired”) at 9 different depths to take water samples, with many replicates.

Once on deck, the rosette sampler was flooded by scientists, learning what we’re going to have to do over the next 71 CTD casts (the black dots on the map). There was strict order to who sampled the water bottles, to minimise contamination. The first samples were used to measure oxygen, followed by dissolved (inorganic) carbon. This was followed by water samples for salinity, density, nutrients (Nitrate, Phosphate, Silicate), and finally trace metals. This took us about an hour to learn all the very careful techniques, and all the logs we had to fill in – when we do it for real, we’ll have to be much faster. After this, the hydrophone was lowered to listen for marine mammals (a sperm whale was heard in the distance) and to study marine noise.

We are now steaming for Iceland where we will begin our transect line, and all the CTD casts (and well as the “epibenthic sled” – more on this later!). We have crossed the Rockall Trough and the Anton Dohrn Seamount – this seamount may cause more mixing which is a good environment for creatures. Perhaps this is what attracted the beaked whales we saw. I was surprised how blue the water is here.

However… we have to make a detour to pick up a poorly ocean glider, with a failing battery pack (the red star on the map). Ocean gliders are marine robots. This one had glided from Scotland all the way to Iceland and back, until one of the battery packs had failed. We have been in contact with it and hope to pick it up tomorrow – stay tuned…

Here we go!

by Stefan Gary

Welcome to the 2016 Extended Ellett Line blog. We’re aboard the RRS Discovery for a 18-day science cruise between Scotland and Iceland. We left the port near Glasgow this morning after a couple days of spectacular sunshine while loading equipment. As of this writing, we’ve just passed Islay and headed into pea soup fog.

The Extended Ellett Line is a repeat hydrographic section where we have been measuring the water properties for more than 40 years. The Extended Ellett Line is also the eastern termination of the OSNAP line. This year, some questions that our cruise will help to address are:

1) Is the temperature of the open-ocean, upper waters between Scotland and Iceland continuing to decrease?

2) Can we still detect the imprint of the exceptionally strong 2013/2014 winter storms in the subsurface waters offshore of the UK?

3) Be there whales? In particular, how many beaked whales and sperm whales can we detect with a towed hydrophone?

4) Have microplastics made it into the bellies of deep sea creatures?

Over the next 17 days we will post short updates and thoughts about life at sea on this blog and tweet with #AtlanticObs.