11 August 2002 - Science ends, refit starts
RRS James Clark Ross Diary
Position at 1200: 5Drydock, Fleet Support Limited, Portsmouth Naval Base
The End of Science and refit
Firstly apologises for the lack of recent updates, but you might get some impression from what follows just how busy we have been.
When we last wrote we were in the middle of a cruise for the British Geological Survey (BGS) off the North West coast of Scotland and their final installment follows a little later. This is also accompanied by a article from Mick Mackey from the University of Cork in Ireland on his observations of whales and seabirds, while we've been conducting the surveys. Thanks to Mick and all the BGS team for their contributions, it's much appreciated.
So what has the JCR been up to in the mean time? Sunday the 28th July saw the end of the science programme and we steamed southwards round Ireland and into the English Channel heading for Portsmouth, where we arrived on the 31st July. Our first task was to demobilise the cruise equipment from this cruise and samples and equipment from our earlier Arctic excursion, then it was on with the task of refit. This year we have moved to a new yard for our annual dry-docking, to a company called Fleet Support Limited (FSL) who are based in the Royal Naval dockyard here in Portsmouth. Below you can see one of the famous landmarks on the Portsmouth skyline, that of HMS Victory which, of course, was Nelson's flagship at the battle of Trafalgar back in 1805.
We are scheduled to spend a little over three weeks in the yard having a lot of jobs done to upgrade the ship and make her ready for another voyage southwards in September. One of the major jobs this year is to start the process of replacing the protective skin on the hull. The steel making up the hull has a very hard coating applied to it to resist the worst effects of the ice and sea, but obviously after eleven voyages south even this is showing it's age. So this year we are replacing 1000 m² of the worst effected areas around the bows and sides. The first job then is to remove the paint and remaining covering on the hull which is done initially with very high pressure water blasting, which is then followed by shot blasting to prepare the steel for treating. The picture below shows this work in progress.
This is the stage that we have reach at present with the preparation almost completed. So in the coming week the treatment and a fresh coat of paint will be applied to bring the vessel to looking like new once more. We hope to bring you some more pictures of the ship and the work taking place either later in the dry-dock or shortly afterwards, but as a taster below we have John Summers our Scientific Deck Officer adding some scale to the propeller and rudder.
The Science bit in the middle
The Second Installment from the BGS Crew
Geological Background of Survey BGS02/02, Hatton Bank. Our second survey area is north Hatton Bank, the last piece of continental crust of significant thickness before the North Atlantic oceanic crust begins. Rifting affected the bank as it affected the Rockall Trough 150 to 55 million years ago. However, during the last 55 million years, Hatton Bank has experienced three or four compressional phases which have been recorded in the rocks.
Our survey of Hatton Bank has revealed some interesting structures within the basalt layer and the sediments lying immediately above. The rocks have been folded and faulted on the southeast side of the bank, rather like folds in a carpet (it may transpire that the whole of north Hatton Bank is one large amplitude fold). By examining what layers have been folded and what layers haven't, we can estimate the time of folding. Also, if we map the folds in detail, their orientation should tell us the direction of the forces that led to their deformation. We may then look to what mechanisms drove those forces: were they effects from the opening of the nearby Atlantic Ocean, effects from movement along large scale faults or effects from the building of the Alps?
The hard rock of the basalt on Hatton Bank (and indeed all over the Atlantic margin) impedes the acoustic energy used to image the rock layers. This means we cannot 'see' the rocks that lie beneath the basalt, which are the sediments deposited in rift basins in the Rockall area when the Atlantic Ocean was trying to open. The rocks below the basalts are likely to be Cretaceous in age (100 million years old) but could potentially be much older (up to 320 million years old). This age range spans the Jurassic period (200 to 150 million years ago) when many oil forming rocks were deposited. Jurassic rocks are extensive in the North Sea, a well known oil province, and there is the possibility that oil exists in the Rockall and Hatton areas. Presently, the only way we could image the sediments beneath the basalts would be through 'windows' in the basalt. These would be areas which escaped being covered by basalt, or where the basalt has been eroded away.
More information on Hatton Bank and its potential for hydrocarbons can be found in HITCHEN, K. 2001. Is Hatton Bank the new Jeanne d'Arc Basin? First Break, 19, 358-360.
The Other Science Department Onboard....
Budgies and Blubber of the Blue
Cetacean and Seabird Observation Summary
As part of the BGS's regional geophysical survey in the Hatton-Rockall area, I was invited to join RRS James Clark Ross to conduct general surveys of offshore cetacean (whales, dolphins and porpoises) and seabird populations. The current survey is an extension of the Irish Cetaceans and Seabirds at Sea study, which is based at the Coastal Resources Centre, University College Cork, Ireland. Observers involved in the study have already made some interesting observations, including the sighting of the rarely encountered blue whale, northern right whale and the elusive sowerby's and true's beaked whales. The project was undertaken on behalf of the Rockall Studies Group and Porcupine Studies Group of the Petroleum Infrastructure Programme - a programme set up by Ireland's Department of the Marine and Natural Resources in 1997. The main aims of the research are:
- to establish reliable baseline information on the distribution and abundance of seabirds and cetaceans off western Ireland throughout the year;
- to identify critical habitats for these species; and
- to provide independent scientific information essential for conservation and management purposes.
It was also my job to inform BGS scientific staff of visual cetacean presence prior to activating seismic equipment (i.e. sparkarray and airguns) so that operations could be deferred until the animals were considered a safe distance from the vessel (>500m). I also attempted to assess any behavioural responses of the cetaceans to underway seismic operations.
The primary study area during the cruise extended from the continental shelf edge, north-west of the Isle of Lewis, across the northern sector of the Rockall Trough, concentrating in the area around the Rosemary Bank, and westward to a region north of the George Bligh Bank and the Hatton Bank (Figure 1). Surveys were also conducted on the homeward leg, as the vessel steamed south over the Anton Dohrn Seamount, through the Rockall Trough and over the continental shelf southwest of Ireland.
Full surveys were conducted during each day of the 18-day cruise (12th July - 29th July 2002). The average working period for each day was restricted to 5.30am and 8.00pm GMT, although ship downtime, high wind conditions and severe sun glare limited available survey time further. Over 498km² of trackline were surveyed during a total of 154 hours 20 minutes (average ~ 8.5 survey hours per day). The survey effort area (km²) achieved for each ¼ ICES square, each measuring 15' latitude x 30' longitude, is highlighted in Figure 1.
Since the JCR left Stornoway, a total of nine cetacean species have been recorded, comprising a total of 262 animals that were recorded during 49 sighting events, including four multi-species encounters. Seven toothed cetacean species (n=233 animals) and two species of the filter-feeding baleen whales (n=13) were positively identified during 43 encounters. In addition to those positively identified animals, 16 unidentified cetaceans were observed during six separate encounters, including the distant sighting of a breaching beaked whale, and the remains of a dead large whale species.
All but two of the toothed species were recorded within the survey area during seismic operations. The two exceptions, Risso's dolphin and white-beaked dolphin, were observed over the continental shelf, northwest of the Isle of Lewis. The harbour porpoise was represented by a single, dead individual during the initial stages of the first seismic line (NRT1). The most numerous and frequently encountered species was the long-finned pilot whale, which was sighted on 23 separate occasions (47% of all encounters). This squid-eating species accounted for over 72% of all individuals recorded (n=189 animals). With the exception of a single encounter, all pilot whale sightings occurred at depths between 1100-2500m. The pilot whale was the only species that appeared to display a positive response to seismic operations (i.e. actively approached vessel and arrays). This investigative behaviour has been observed during previous surveys on seismic vessels, and may help to explain the relatively high encounter rate. On two occasions, immature pilot whales were observed swimming in close association (within 30m) of the sparkarray, in a similar manner to bow-riding dolphins.
The second most frequently encountered toothed whale was the deep-diving sperm whale. Twelve sperm whales were recorded during ten sighting events, although nine animals were observed in close proximity to other individuals (i.e. with 1-2km). Although most sperm whale sightings tend to occur in waters of great depth, three individuals observed during HB13 were recorded over a 4-5mile course at a depth of ~590m. All but one sperm whale encounter occurred during seismic operations, where they appeared to display total indifference to the acoustic activities. In most encounters, sperm whales were observed "fluking-up" indicative of a deep dive. The only species that showed possible signs of avoidance during seismic operations were the common dolphins (Figure 2) and white-sided dolphins, which kept an unusually cautious distance from the vessel.
Only two species of baleen whale, the fin and minke whales, were identified throughout the cruise, all of which occurred during seismic operations. Eleven fin whales were recorded during five encounters. Fin whales (Figure 3) have a reputation for showing indifference to shipping traffic, and like the sperm whales mentioned previously, they displayed little to suggest that they were affected by the seismic activity. Although one large individual breached clear of the water in a very spectacular display, it cannot be said with any certainty that this behaviour was in response to the airguns and sparkarray. Three individuals observed well ahead of the ship's trackline, steadily swimming directly towards the vessel, moved past at a cautious distance (~400m) without breaking their "stride". The two minke whales observed during a single encounter, slipped across the ship's bow 800m ahead of the trackline.
Approximately 3300 seabirds, representing 19 species, were recorded during the 18-day survey. In addition, 32 waders were observed during the latter part of the survey. By far the most frequently encountered seabird species (~55% of total) was the northern fulmar (Figure 4), which was a constant companion throughout the survey period. Although low concentrations were recorded in most areas surveyed, large concentrations were periodically observed in association with fishing vessels. Northern gannet numbers were highest over the continental shelf region, where foraging adults dominated. The low concentrations of northern gannets recorded in the northern regions of the Rockall Trough and Hatton Bank, were generally dominated by juveniles of varying age-classes. The low numbers of black-legged kittiwakes noted during this survey is in contrast to the moderate densities observed during a similar survey in the southern Hatton Bank region last May. Interesting observations of migratory species were also made during the study period. The sighting of eight individual sooty shearwaters and a single great shearwater marks the onset of the migration of these pelagic species across the North Atlantic. They will continue their migration down past Ireland and the British Isles during August and September, returning to their breeding colonies located on islands east of South America. The 22 small skuas (pomarine, arctic and long-tailed skuas) marks either the end of the northern migration to their northern breeding/feeding grounds or the early departure to the southern wintering grounds off Africa and South America. The latter scenario is indicative of poor "lemming years" in the breeding grounds of the Arctic tundra. Only two representatives of the auk group were recorded - the common guillemot and the Atlantic puffin. The Atlantic puffin was observed in low concentrations throughout the survey area, while occasional records of single common guillemots were made spasmodically. Records of storm petrels were restricted to waters east of the Rockall Trough, with the highest numbers recorded off the breeding colonies along the southwest Irish coastline.
And Finally from Mick we see him in his usual position up on the monkey island scanning for his next sighting.
Fishing for Spagetti
The final piece of work before heading south was to recover a mooring that had broken free and was drifting in our area. It had been laid by participants of our Arctic cruise from another ship last year. Maybe a fishing boat had snagged it or part of the equipment had failed, either way the main buoy was on the surface sending out it's position. As can be seen from the pictures below the task was anything but straight forward as the cable had managed to tie itself in knots, but the deck crew got it sorted out. This was good as not only did we recover most of the valuable instruments with their data, but also removed a hazard to shipping as well.
Above: Left - the after deck during the recovering operation. Just a little blue line! Right - GeorgeStewart (Bosun) and Derek Jenkins (AB) unravelling the "knitting". Click the images to enlarge them.
Department of the Week
It was pointed out on recent update that some of the deck department had been missed out so to hopefully rectify this we have the present day shift.