09 Feb - Water, water everywhere....
RRS James Clark Ross Diary
Noon Position: 55° 22.7 S, 34° 21.5 W)
Distance Travelled since Grimsby: 21821.5 Nautical Miles
Air temperature @ Noon today: 4.7°C
Sea temperature @ Noon today : 3.3°C
Weather: Moderate/poor, WNW, 5, 982.0 mb
Water, water everywhere.........
The James Clark Ross has spent another week at sea and despite seeing several islands along the way, we have not managed to get ashore anywhere. We have been busy finishing off several more transects traversing the Scotia Sea between South Georgia and as far south as the ice edge. Our route took us far to the east and we came back through the South Sandwich Islands. These are a barren chain of volcanic islands connected by a submarine ridge that make up the easterly boundary of the Scotia Sea. They were discovered by Captain James Cook in HMS Resolution who sighted Southern Thule, the most southerly of the group, on 30th January 1775. The Admiralty Sailing Directions for the region describes the local weather: 'snow and poor visibility are frequent, rendering the islands difficult to approach...the mountain summits are almost always hidden by low cloud. The sun rarely shines for more than a few hours at a time'. The islands are poorly charted and most of the islands are volcanic with uncharted and ever changing dangers. Landing is extremely difficult and 'probably impossible except for by helicopter' for many of the islands. However they do have large penguin colonies and we saw many penguins in the waters round the islands. We passed carefully through Forsters Passage between Bristol Island and Southern Thule, 228 years after they were first discovered. To see our track update please click below.
We have also passed a couple of rocks to the southeast of South Georgia called the Office Boys on our way to South Georgia. Writing this on Sunday evening we are currently off the northeast coast of South Georgia and should be calling in at King Edward Point (KEP) tomorrow. There are fantastic views across to the sun setting over the spectacular South Georgia silhouette.
What makes the JCR a science ship??
We are currently in the middle of a 7 week science cruise in the Scotia Sea and are investigating many factors affecting the transport and survival of krill. The JCR has to fulfil a complex range of requirements that allow the scientists onboard to complete their experiments. This ship has a range of features that permit a wide range of investigations to be performed using the JCR as a platform for science. I'll try and explain how and why we can do the science we can.
The JCR was designed as a replacement to RRS John Biscoe in the late 1980's. The ship needs to fulfil 3 main roles:
- The logistical supply of people and supplies to the Antarctic bases
- To be ice strengthened and operate in Antarctic territories with the ability to break through ice
- It had to be a ship that could perform and support a wide range of scientific research
This tridentate role shaped the ship and resulted in the complex final design. BAS wanted a ship that could perform two main types of science, biological and geological. Representative groups of scientists were consulted and agreed the features that they wanted the ship to have to enable them to perform their experiments......
The JCR has a large array of very sensitive acoustic sensors at its disposal with echo sounders, sub bottom profilers and swathbathymetry. Fitted within the hull these instruments require the ship to be as quiet as possible. There are two main areas of noise production from a ship, the flow of water over the hull and the engines inside. The design of the hull is critical and the flow of water over its surface needs to be as smooth and clean as possible to reduce any vibrations caused by irregular flow. Acoustic sensors also need a good contact with the sea water beneath them so lines of the hull ensure that there is minimal aeration under the hull producing optimum acoustic transmission i.e. no bubbles of air are washed underneath the ship. The propeller is very quiet compared to normal ships when sea going but can also produce the power necessary in ice conditions. Since any vibrations caused within the ship are transmitted to the water outside via the hull vibrating, machinery is mounted on resilient rubber mounts that absorb any movement. Some are even mounted on a rubber mounted raft as well as their own mounts and so transmit minimal vibration to the hull and therefore to the outside water. Fluid flowing through pipes can also produce vibration and so all pipes are hung on rubber mounts to ensure the minimum of noise is transmitted to the hull. The engine on the JCR is an electric motor identical to that found in nuclear powered submarines and is extremely quiet. The JCR underwent trials at a military testing range where submarines and naval ships are tested and was found have an extremely low noise profile required for science work.
Above: (L-R) The smooth lines around the propeller are clearly visible. Gerry points to some of the resilient mounts on one of the generators. The smooth finish on the hull. Click the images to enlarge them.
Put us there exactly and keep us there!
Science often needs to be performed in an exact geographical position and so the JCR has to be capable of manoeuvring into exact locations. It therefore has to be easily manoeuvrable and be small enough to get into little bays and also to stay in an exact position in the open ocean. Mounted in the front and rear of the hull are two thrusters. These are not propellers but openings in the hull that can suck water up and then push it out in any given direction. These powerful devices therefore allow the ship to move in any direction, even sideways or backwards. When deploying a drill to the sea bed 4000m below the ship, the JCR needs to maintain it's position exactly above the drill and counteract the wind, waves and currents on the surface. To this end, the ship is fitted with a computer controlled dynamic positioning system (DP) that co-ordinates the rudder, propeller and thrusters to keep the ship over an exact location as defined using a GPS. This system is critical for many vertical deployments. The electric motor and shaft configuration and lubrication systems allow extremely low prop speeds for long periods of time to enable the ship to sail at a variable range of speeds including very slowly. This is unusual for most ships but is important for the JCR.
Above: Dave using the DP system (L) and the shaft (R). Click the images to enlarge them.
Keep the water clean
Virtually all of the work over the side of the ship is performed on the starboard side and aft end. This is to ensure that any science is exposed to the cleanest water possible. All of overboards (discharge pipes) from the ship are mounted on the port side and are underwater so to keep any potential contamination away from the science side and reduce any noise pollution caused by discharge falling into the water. The ship has the ability to retain all sewage produced onboard in tanks to prevent contamination of the water around the ship. The JCR also provides the scientists with a constant supply of uncontaminated sea water that is taken up through a dedicated telescopic pipe 1 metre below the ship. This water runs through specially coated and insulated pipes to reduce any alteration to the chemistry of the water and prevent changes in temperature before it reaches the laboratories. We can also provide an extremely pure water that is filtered and distilled. All these systems are there to ensure that the sea around the ship is kept as clean as possible to avoid any error in experiments.
Above: The starboard side of the ship where all the science takes place (L) and the port side of the ship (R). Click the images to enlarge them.
We need space to work
Approximately one third of the superstructure of the ship is dedicated scientific space. The ship contains 6 separate labs (wet, main, biochemistry, radioactive, prep, chemistry). The aft deck is a large open space that is used for the deployment or recovery of equipment. It can also take containerized workshops that are secured down to the deck allowing specialized labs or equipment to be housed temporarily. Important in the co-ordination of science is the Underway Instrumentation Control (UIC) room from which many of the integral acoustic sensors are directed from. This is a large room with many computers, a panoramic window to observe the scientific deck areas and winch controls in that form the hub of science. There is a large bridge with steering consoles facing forwards and backwards allowing navigation whilst observing in either direction. This is crucial when accurate positioning is needed when deploying equipment over the side and complements a system of CCTV cameras throughout the ship. The deck is wooden to provide a pleasant working environment and also protect fragile equipment. The aft deck is lower to the water (having a small freeboard) but without allowing the area to become to wet in heavy seas. For meetings and presentations there is a conference room and we have even got a gravity room in the centre of the ship for sensitive gravity measurements!!
Above: The working area of the deck (top) and the Underway Instrumentation Control (UIC) room. Click the images to enlarge them.
We need space for equipment and specimens
Two workshop spaces are provided for maintenance or construction of scientific equipment in addition to a large dedicated science hold that can also double as a lab. A cold room permits work in temperatures down to -3°C with storage of specimens in -20°C and -80°C freezers. There are explosive and chemical stores to safely transport substances needed for experimentation. The labs have a system to permit all gear to be secured down to the benches in rough seas. The outside deck is also fitted with a universally accepted matrix system that fixes equipment down to the decks. This allows scientists bringing their own equipment to be able to plan ahead and ensures safe stowage of gear.
It's good to talk!
We have a dedicated computer room with a range of computing facilities including a network linking all computers onboard together allowing rapid transfer of data around the ship. There is also a internal e-mail system and communications with the outside world are via e-mail (3 times a day), fax and satellite phone. There is even talk of 24hr internet access in the next year or two, even when in Antarctica. Temporary cabling can be run through watertight bulkheads using a special cicab system that maintains the fire and water integrity of that space. A clean and stable electrical supply is also constantly provided for the sensitive equipment. Integral to the ship is the swathbathymetry that was retrofitted in 2000. This is an extremely accurate acoustic mapping system that looks through a titanium window in the hull of the ship and is currently the most advanced in the world outside of military organizations.
Let us deploy
Clearly much of the science is done by dropping (or gently lowering - Ed) things over the side of the ship. We have two large stern and side gantries combined with 3 dedicated science cranes for deployment and recovery of equipment. The aft end has a stern door with is basically a removable bulwark that can be raised or lowered to allow easier access to the sea. Large nets need the stern roller to aid in recovery. There are hydraulic and electrical power available to equipment on deck if it is needed. The ship has facilities for deploying a wide range of nets, sensors and drills. Any thing from commercial fishing nets with 15 km of wire to piston coring of the seabed on 8 km of kevlar wire! Two winches of 10 and 30 tons use a variety of sophisticated cables with antitwist properties and conducting cables that allow electrical communication with the devices on the end of the wire.
We need somewhere to live!
Scientist need somewhere to live, relax and eat whilst not at work. Since many cruises involve 24 hour science then the ship must be capable of maintaining a community working 24 hour shift patterns. The JCR can carry up to 35 of scientists mainly in single cabins with ensuite. It has a library, bar and other social spaces. The scientists expect other hotel facilities such as showers, toilets, meals provided etc. etc.
Everyone on board is related to science in some way but there are two extra people onboard compared to a normal ship. A deck engineer is responsible for the technical and engineering support whilst a deck officer scientific ops, helps with the practical deployment of equipment and control of winches. The JCR also has 3 semi-rigid inflatables and a work boat for landing shore parties in remote areas.
As you can seen the JCR is a complex ship that has to fit all the above requirements round the logistical and ice strengthened roles. Predictably this ship is a compromise between all of the roles but is incredibly successful in providing a pleasant and efficient scientific working platform. It is sometimes quite bewildering to wander around and realize the complexity of the design the allows so much to be squeezed into such a small ship.
If you want to see more of the ship, why not take the virtual tour?
Unusual whale sightings No 2
On Tuesday whilst cruising along our transect on a beautifully calm and clear day, a large number of whales were observed from the ship. Large numbers of prions (seabirds) were seen sitting on the water in large rafts and seals spotted sleeping in the calm water with just their noses and flippers out of the water. 16 humpback whales, 3 southern right whales and one minke were seen close to the ship feeding on the surface. Several grey beaked whales were also seen about one mile away from the ship. Unusually, the humpbacks and right whales were feeding and swimming next to each other in the water. Fortuitously we stopped at station nearby and observed the whales for a total of 7 hours as they remained in the vicinity engaging in social activities such as flipper slapping and breaching (see pictures below). They were completely unaffected by the JCR passing by. Our echosounder revealed why we there were so many whales present. There was an incredibly dense swarm of krill reaching 60 m down from the surface in a layer approximately half a mile across. The echosounder picture is seen below.
Above: Clockwise from top left: Echosounder view of krill swarms. Humpback tail and flipper slapping, a breaching humpback and a southern right whale. Click the images to enlarge them.
It is unusual to see southern right whales with humpbacks and so this was a lucky sighting. Right whales normally feed on copepods rather than the larger krill. Minke and humpbacks would be feeding on the dense swarm of krill. The exact mechanisms of feeding and the potential of whales rounding up krill into swarms using bubble netting is still poorly understood but may have been taking place here. Interestingly the beaked whales hunt for squid and so would not be feeding on the krill. It is amazing to see so much wildlife involved in a 'feeding frenzy' in a tiny area after sailing through miles of ocean without seeing anything at all.
The krilling fields
After 56 stations and 8 transects we are finally coming to the end of this part of the biosciences cruise. The main point of the cruise has been to investigate the factors affecting the transport and survival of krill across the Scotia Sea. Over the last few weeks I hope to have outlined the basics of the experiments concerning oceanography, primary production and copepods but would now like to give a brief insight into what we have actually been doing with krill themselves.
At each station we have 'gone fishing' with the RMT net. This net is designed to catch krill and we are guided by the echosounder as to where the krill are. So in 21 of the 56 stations we have found krill and have caught some in our nets. Once we have krill onboard it is possible to set up several experiments.
How fast are the krill growing?
Krill conveniently have an exoskeleton almost comparable to a shell. For the krill to grow they need to moult by shedding this hard outer layer before growing a new larger replacement. Growing krill can perform this task approximately every 20 days. So at every station where krill have been present, 300 have been randomly sampled from those caught and kept in individual 500ml pots of flowing sea water. Each day they are observed to see if they have moulted and their old skeleton has been left floating in the pot. This is repeated for 5 days. The difference in the length of the krill and its old exoskeleton can give an indication of growth rates in the field. Krill are also studied onboard for the amount of chlorophyll in the gut and to give an indication of the gut transit time.
What causes krill to grow?
There are three basic factors that regulate how fast krill grow: food, body size and temperature. The larger the krill are the slower they grow. We are investigating the relationship between growth rates and food by comparing growth with the data collected by the primary production and copepod teams. It is important for krill to grow and put on fat so as to survive periods of low food and also to spawn.
Why do we need to know about the krill growth rates?
The factors that affect krill growth also have a key role in population dynamics of the krill stocks. A better understanding of these factors controlling growth can lead to the creation of models that allow prediction of population change and stock assessment. These models can then be combined with fisheries research to be used for better management of the fishing industry. Growth is also related to the energy budget of a system and gives an indication of the metabolism of the krill and also their health which can then be related back to food availability and use.
Things to do back in Cambridge
Many of the krill that are caught are frozen immediately for a variety of reasons. Genetic analysis looking at the ratio of RNA to DNA will be performed. Hormonal studies, lipid and elemental composition studies of the krill will also take place using the krill collected whilst on the cruise. The main thrust of this work is looking for regional changes linked to the food environment across the Scotia Sea and will be related to the primary production and copepod work. It also gives the scientists something to do for the rest of the year!!
Thankyou this week to: The Office Boys!
Coming up next week: Jollies galore, boys and boxes and baleen.