Thursday, 2 August 2012

Day 22 - Home to Southampton

Well, we’ve made it back to shore and the cruise is finished. We’ve unloaded our gear and the RRS Discovery is already on the next expedition headed towards Iceland.

As the Principal Scientist on the cruise, I’m ecstatic about the results we achieved. There is a great team of scientists, technicians and ship's crew to thank for making the fantastic data collection possible.

We not only collected a great selection of seafloor samples, but collected more than 300km of seafloor photographs - more than 186 miles.

Image showing 18 x 1 m segment of photographic data with the long-tailed sea cucumber psychropotes longicauda visible. Scroll to view more of the seabed.

This data will allow for a study of unprecedented scope in terms of scale and detail for abyssal depths.

It will take us more than a year to process all our samples and analyse all the pictures, but the result should provide new perspectives on biodiversity and the implications of future climate change for abyssal plain habitats.

In the weeks and months to come this website will continue to document project progress. We will have lots more to share before too long!
Thanks for your interest,

Henry Ruhl


Wednesday, 25 July 2012

Day 20 - Like a Rolling Stone

While others are acquiring spectacular images of the seafloor with Autosub, I’ve been amusing myself by... um… collecting stones. We find these embedded on the surfaces of megacores. Most of the stones originate from the higher points on the abyssal seafloor (i.e. the shallower sites), probably because these are areas where they are exposed by sediment winnowing.

Surface of stone with delicate network of Telammina; note the tiny
chambers strung out along the very narrow tubes that make up the network.
This genus is common on hard substrates at many sites in the deep ocean
A few are ‘clinker’ – lumps of burnt coal discarded by steam ships. Clinker is a very common human contaminant of the ocean floor, which is surprising since steam ships only operated for a period of about 100 years. However, most of the stones are bits of rock, almost certainly dropped by melting icebergs during the last glacial period. They often have a black coating, probably of iron-manganese oxide.

Despite initial appearances, deep-sea stones can be quite interesting. The ones that are exposed at the surface provide a hard substrate on which different creatures can settle, and are often teeming with life.

A stone with a brachiopod (Pelagodiscus) attached to the surface.
Also visible are two mat-like formations, one dark grey and
the other whitish in colour
During this cruise we found animals such as brachiopods and bryozoans on the stones. However, by far the most abundant organisms were foraminifera, single-celled protozoans that Laetitia has already written about. (Day 16)

Most foraminifera – forams – live in the soft sediment but others fix themselves to hard substrates. We found a wide variety of these attached forams on the stones.

This solid dome shows some internal structure suggesting the presence
of chambers within the dome. This suggests that it is a foraminiferan belonging to the 
Komokiacea.  This superfamily is extremely common in the deep sea, although
only a few species live attached to hard substrates

Some were simple mud domes, others included extensive networks of fine tubules and flat mat-like formations. But the most common was a delicate net of minute tubules with tiny chambers positioned along them. Unlike most of the encrusting forams, this one has a name – Telemmina.

The stones provide sanctuaries on the seafloor for foraminifera and animals that could not survive in the sediment. In the Pacific Ocean, manganese nodules are often densely covered with similar organisms. Nodules are much less common in the Atlantic Ocean, so it’s fascinating to see the same kinds of foraminifera settling on stones that were transported from distant continents by icebergs thousands of years ago.

An extensive network of fine tubules covers a large area of
this stone, while on the left-hand side is a mat-like crust. Both are
assumed to be foraminifera.

Andrew Gooday

Day 20 - The ship down below

The engineers are in charge of the ships engines, machinery, its smooth operation and repairs. It’s an important job and one that keeps the six engineers aboard hard at work.

One of the diesel-electric engines
Declan, the 3rd Engineer, passes me a pair of ear protectors as we begin our tour of the engine rooms below deck. The first things you notice are the four diesel-electric engines powering away, each producing 1550 KW. They provide us with the electricity used for the lights, right through to the propulsion of the ship.

Below deck there is more machinery that the engineers are responsible for which includes a sea-water to fresh water generator, the hydraulic systems for the winches, refrigeration units for the scientists laboratories and galley fridges, sewage treatment and a pressure system for the vacuum toilets.

We reach the control room, which looks as impressive as the ship’s bridge, with read outs for all the machinery’s parameters such as pressures and temperatures. In an emergency, if the bridge is down, the entire ship can be controlled from the engine room control desk.

Declan explains that the engine room is an UMS system (unmanned machinery space), which means it doesn’t require full time attention at night. However the UMS computer is linked to the engineers’ cabins. A fault will trigger an alarm alerting the engineer on watch that night to any problem.

Chefs Mark and Lloyd in the galley
Arguably one of the most important roles is that of keeping everyone on board fed throughout the three-week journey. With 43 people to feed this is a big operation.

Before our trip began enough food was stocked from suppliers in Southampton to fill two giant walk-in fridges for fresh fruit, vegetables and dairy, and two walk-in freezers for meat and frozen food. There is also an entire room for tinned food and condiments.

It has been known for the galley staff to stock the ship from food outlets abroad, such as the Bahamas or Chile. It’s possible to keep the ship fed for six weeks straight, although towards the end there does tend to be less fresh produce. For our trip we are able to enjoy fresh food throughout.

John Benning

Tuesday, 24 July 2012

Day 19 - Running the ship

The running of the RRS Discovery can be split into three main teams: the officers and deck crew; the engineers; and the catering staff, all of whom are governed by the ship’s Master. In total, there are 21 crew members, each and everyone being vital and working as a close team throughout.

It should be pointed out that from the ship’s crew point of view, they are all mariners together, working for the ship herself. It is generally believed that she (the ship) has a soul and most certainly a personality (described as cantankerous at times).

The Master, Peter Sarjeant
The Master is ultimately responsible for the entirety of the ship and all those aboard. The Master (referred to by the crew as ‘the Old Man’) is the key decision maker on board.

In the Merchant Navy, the Master is equivalent to the position of Captain. Peter Sarjeant has been Master for 24 years. Having joined the National Environmental Research Council in 1999 he has subsequently been in charge of the RRS Charles Darwin, James Cook and the Discovery.

As I sit talking to him in his quarters at the bow of the ship, he tells of adventurous trips of gigantic seas and near misses with hurricanes, I get the impression he very much loves his job, and in particular, the enthusiasm he sees from the scientific team. He tells me of how times have changed over the years. For example when he first began, the weather reports would come in by Morse code and it would be his job to plot out the isobar contour maps by hand.

Day-to-day working life entails management meetings with the scientists, officers and chief engineer, writing reports and communicating with shore. On top of that he is on call 24 hours a day.

Second officer William McClintock planning
the route for Discovery’s next trip to Iceland
The officers are in charge of the navigation of the ship and are a fail-safe for safe operations. Working 4-hour watches they man the bridge 24 hours a day. Each officer has also to deal with life saving drills, fire fighting equipment and medical matters.

Long distance journeys to far-away ports require careful planning. The nautical charts and publications are also checked and updated if required.

From the bridge the officers are in contact with the deck crew who work hard to organise the scientific machinery on deck. Working from the winch room, the deck crew will operate winches that can lift up to 10 tonnes of equipment. At the same time the officers on the bridge keep the ship stationary by means of carefully balancing the ship’s propellers and thrusters against the oncoming swell and wind.
Seaman William Mclennan, in the winch room

This is an incredibly skilled task. The RRS James Cook has dynamic positioning that automatically keeps the ship on position. The replacement RRS Discovery will also have this feature. But it is the experience and skill of the crew that keeps this 50-year-old vessel on station during deployments.

John Benning

Day 19 - The Abyssal Plain. Not so Plain after all

This is the main event! We mentioned before that Autosub6000 was being prepared for duty, and after a furious couple of weeks of work at Porcupine Abyssal Plain, the sub has successfully completed seven missions, collecting bathymetry data and over half a million photos of the seafloor.

Photo strip showing a dumbo octopus and a sea cucumber
These surveys are designed to gain a broader perspective of how communities might differ between abyssal hills and flat areas, which is similar to understanding how communities of animals might change as one moves from a valley to the summit of a mountain. On land it is easy to confirm on the ground what we can see from satellite photographs, but this is far harder in the deep-sea because we can’t see through the water using light. Instead, we have to use sound-based mapping techniques such as sonar to map large areas of the seabed and confirm them with remotely taken samples like those from the megacorer or photographs. The benefit of using Autosub for collecting photos of the seafloor is that it can cover vast stretches of the seabed quickly while collecting a huge number of photos, along with other data about the environment. The photo transects we’ve collected during this cruise span an area about the size of a medium-sized city, enabling us to view a greater area of the abyssal landscape than has been generally possible for deep sea areas.

Autosub has been deployed with two cameras. The downward facing camera takes photos directly below Autosub, and these photos are used to assess the number and types of invertebrates that live on the seafloor in different areas of the plain. Sea cucumbers are the dominant type of large invertebrates that we see in the abyss, and there are at least ten different varieties in our photos. Autosub takes one photo every 0.8 seconds, so the photos overlap. This overlap means that photos can be stitched together into long strips, giving a continuous picture of the seafloor. In just a few days, we have taken more than 300,000 photos with the downward camera, which will take months to analyse!

The forward facing camera is being used to look at the numbers and distribution of abyssal fish. Fish decline in number rapidly with depth, with only a few species able to survive on the limited food supply in the abyss. The rarity and mobility of fish means that surveys must cover large distances to determine their distributions over the seabed, which is why Autosub is such a valuable tool. Fish species in the abyss look quite different from fish that you see at the fishmongers; they are dominated by eels and rattails, and are typically scavengers that can cover long distances using relatively little energy to try and find food. We need to use a forward-facing camera to monitor fish because they are mobile, so can be startled and swim away before being seen by the downward facing camera. So far, we have collected around 250,000 photos, which means lots of fish to look for!

A steep volcanic rock face on the abyssal hill
In addition to Autosub, we have used SHRIMP (Sea floor High Resolution Imaging Platform) a towed camera system, to photograph one area of cliffs that was too steep for Autosub. The SHRIMP system had forward and downward video cameras and a downward facing still camera. Using this, we were able to see some rare rocky outcrops in the abyssal plain! This was really exciting, since this environment is largely flat and covered in muddy sediment.

As we come to the end of the highly successful Autosub missions at the Porcupine Abyssal Plain and anticipate exciting new finds, we find that we are positively swimming in photos!

Monday, 23 July 2012

Day 18 - Size Matters

We are collecting samples of the seafloor sediment for their particle size distributions to be analysed. This information tells us about the basic seafloor environment that animals live in and on. We already know that they live at high pressures, low temperatures and without light, but what is the bottom like?

The seafloor has hills and flat areas that are surveyed with bathymetry, and we can add the particle size of the sediments to that information. Due to the interactions of particles with ocean currents, the particles on higher areas can be coarser (i.e. sandy), than areas in valleys or flatter areas, where there can be higher proportion of very small clay particles. Core samples are sliced into several depths, and will be analysed at NOC. We shine a laser into the samples, and measure the light diffraction to find the size of the particles, since particles of different sizes bend the light at different angles. We can then determine the proportion of particles of each size.
The megacorer collects sediment in its tubes

Much of the sediment at the Porcupine Abyssal Plain is very soft and light brown in colour. We were very interested to see stones that have fallen from melting icebergs. These stones have travelled far from the continent, and provide a hard surface for some fauna to grow on. Clinker dropped from steam-powered ships provides other hard surfaces.

Sediment contains organic matter that falls from the surface ocean, which is consumed by deposit feeders such as sea cucumbers. Soft sediment with small particles is important for feeding and for fauna that bury themselves into the sediment. Looking at particle size differences at different locations around the plain can give us important information about spatial differences in faunal communities in the deep, potentially explaining why we might find differences in one area when compared with another.

Jen Durden and Steve Lawler

Friday, 20 July 2012

Day 16 - The tiny, tiny details

Foraminifera - they may be tiny, but if you look carefully…

H. elegans
Forams are single-celled organisms, which can be found living in deep-sea sediments. Benthic forams, which live in the seabed, are among the most common organisms living in today’s oceanic environments. Forams come in many different shapes and sizes and their structure can be quite elaborate. They have a test (shell), which is made either of calcium carbonate that they secrete, or from agglutinated sediment: bits of fine sand and sediment particles that the forams find on the sea floor.

Foraminifera are being collected on this cruise using the megacorer. This device takes sediment core samples from the ocean floor. The megacorer is lowered off the side of the ship to the sea floor to depths of around 4800m where the cylinders are pushed into the seabed.

Epistominella exigua
The megacorer is used to collect both macrofauna (organisms retained on a 300 μm mesh) and meiofauna (organisms that pass through meshes of 500 μm but are retained on a 40-69 μm mesh). The foraminifera fall into the group meiofauna because of their size. Macrofauna samples are collected in 100mm diameter cylinders, whereas meiofauna, (because they are smaller) are collected in 70mm diameter cylinders. Once back at the surface, the cores are taken off the megacorer and into the laboratory on the ship where they are sliced horizontally into twelve depth layers. Hundreds of forams can be found just in the top one cm layer of a megacore slice.

Bulimina aculeata

The samples collected during the cruise will be taken back to Southampton and used to understand the vertical distribution of forams throughout the sediment layers. Also, the relationship of foram distribution to the topography of the sea floor at the Porcupine Abyssal Plain will be investigated.

Trumpet Lagenammina

Laetitia Gunton PhD student at National Oceanography Centre Southampton and Natural History Museum, London

Images: A variety of deep-sea benthic foraminifera