When most land lubbers look out of their window first thing in the morning, they are likely to spot a blackbird, sparrow or blue tit bouncing around the backyard or bickering on a bird-feeder. When we here on the James Cook awake and peer out of our cabin’s portholes, the first thing that we’re likely to encounter, are a flock of Great Shearwaters majestically negotiating the storm-induced swells that have either gently rocked us to sleep or violently thrown us out of the scratcher. As you can probably gather from the ornithological introduction, I am the ship’s bird watcher. I am also responsible for the visual and acoustic records of those whale, dolphin and porpoise (collectively known as cetaceans) populations that inhabit the offshore waters of the Mid-Atlantic Ridge, although we haven’t caught sight of any blubbery beasts for a few days now!!
This Monday morning was a particularly fine Monday morning. Clear sky, flat sea and little wind – a bird observer’s dream day out. The James Cook had been making steady progress at 4 knots since 5.15am, trawling the sea-floor for specimens that would keep Nikki’s scalpel-bearing troops busy for the afternoon. David also had his camera primed and ready for any unique-looking beastie that survived the ascension from darkness to daylight. I too prepared myself for a busy morning, surveying the ocean ahead positive in the belief that something big was going to break the surface soon. The survey started brightly when a small group of Great Shearwaters crossed the bow and landed no more than 100m from the ship – a rare sight indeed. While taking a couple of photos of this elegant pelagic seabird, I noticed that the settled flock appeared to be keeping pace with the ship’s progress. When the seated birds began to overtake the vessel I knew something was awry. Alas, the net had got itself snagged, and in an effort to free it from the basement the second mate, Rob, had slipped the ship into reverse.
Second Mate, Rob, enjoys a good Force 9 storm.
After nearly six hours of careful maneuvering the gear remained firmly attached to the ocean floor, so the decision was made at 15.00 hours to employ the ship’s muscle to persuade the net free from the ocean floor. From 2600m below the surface the benthic trawl gear, or what was left of it, should have taken about an hour to surface. Unfortunately, due to the great strains placed on the gear during the tug-o-war haul, the cable snapped rendering the gear, and its contents lost.
Once the residual cable was back on deck, CTD number 42 was deployed down to 150m to collect samples for Gavin’s chlorophyll analysis and Victor’s optical cast was also sent into action. Chlorophyll levels are used to estimate variations in phytoplankton biomass through the water column and supplies a measure of how productive a body is at any given time. Gavin indicated that the chlorophyll levels for the northwestern stations have been surprisingly low. Gavin believes that we have arrived at the tail-end of an algal bloom, which is currently senescing. He also indicated that the water column in this region (54 10N, 36, 06W) has a mixed layer down to 40m, which was probably driven by the recent Force 9 storm.
CTD 42 comes up for air.
The Force 9 storm also impacted on Gavin’s Reflectance Radiometer, which resides on the meteorological platform at the pointy end of the ship. Together with Viv, Gavin repaired the cable, which frayed and broke during the storm. This instrument measures the reflectance of sunlight from the sea surface, which in turn, validates the remotely sensed data generated from ocean colour satellites (e.g. SeaWIFS, MODIS, MERIS).
Gav & Viv at work on the Reflectance Radiometer.
The NOCS Shrimp that was deployed last night commenced recording images of the ocean floor at 23.30 last night. The two and half hours of recordings that resulted included images of brightly-coloured Holothurians (i.e. sea cucumbers) and tall columnar sponges. Some of the images generated from Nikki’s PAL lander’s most recent outing included Cusk Eels, Pycnogonids (i.e. Sea Spiders), Rabbit Fish, Blue Hake and Grenadiers.
While I have your attention, I may as well give you a 3-week summary of some of the seabirds and cetaceans that we have observed to date:
Sixteen species of seabird have been observed since James Cook left Bantry Bay, Ireland on July 15th. The most frequently encountered species is the Northern Fulmar, particularly in the north western sector of the survey region. The Great Shearwater (pictured) has consistently been observed in moderate concentrations together with the odd Sooty Shearwater, as they migrate north from their island breeding grounds off the east coast of South America. Both juvenile and adult Arctic Terns were observed in small groups of up to seven birds over the south western station during their southward migration to Antarctic waters. All four skua species commonly observed off Ireland and Britain have been noted over the MAR. The Arctic Skua has been frequently recorded harassing the flock of Great Shearwaters that constantly hover behind James Cook like a child’s balloon at a town fair.
The identity of the most interesting seabird “sighting” for the trip thus far has yet to be confirmed. While investigating a group of pilot whales, I photographed a passing Great Shearwater. On examining the photograph later that evening, I noticed another bird flying alongside the shearwater. This bird may be a Zino’s Petrel (Pterodroma maderia), Europe’s rarest breeding seabird!! Formerly believed to be extinct during the 1960’s, Zino’s Petrel is now classified as Critically Threatened with a current population of 250 to 400 birds. Unfortunately, I didn’t see the petrel – I just photographed it.
The Great Shearwater.
Seven species of dolphin and whale have been recorded during the survey’s first three weeks. The most commonly sighted species has been the aptly named Common Dolphin, although the Long-finned Pilot Whale (pictured) also became a regular visitor once the James Cook reached the southwestern stations. Occasional sightings of Striped Dolphins and Atlantic White-sided Dolphins have been punctuated by regular distant encounters with adult and juvenile Sperm Whales. The most significant sightings of the survey involved a single Northern Bottlenose Whale and a pod of five Sowerby’s Beaked Whales.
A tight family group of Long-finned Pilot Whales.
A day that began with bright skies and flat seas has suddenly deteriorated this bleak Monday evening into thick sea mist and Force 10 winds – time to down tools and hove too.
University College Cork