Friday 6 September 2013

Land ahoy!

After spending two successful weeks surveying the Pobie Bank Reef, we finished the planned acoustic work in block four on Wednesday evening, before starting our journey back to Aberdeen.  We’ve really enjoyed finding out more about the seabed within the survey area, but are now looking forward to the prospect of getting back to dry land!

The day shift

The night shift

We were welcomed back into Aberdeen harbour by a friendly seal and a lovely sunny evening. We’d like to thank the scientists from Marine Scotland Science and the great crew on board the Scotia for all of their help over the last few weeks!

Entering Aberdeen harbour

Wednesday 4 September 2013

Rock around the clock

The last few days have been busily spent ground-truthing at stations across section 3 of the site. The seabed within box 3 has been particularly interesting, with complex sections of bedrock and boulders, providing homes for a range of wildlife. The underwater video has identified some especially vibrant scenes, such as the wall of brittlestars, orange dead men’s fingers (Alcyonium digitatum) and as yet unidentified purple encrusting species shown here.

We’ve also seen several sunstars, different types of crab and anemones. We had another ling follow the camera plum line and a large cod came into the view of the video for a while – our camera seems to be getting lots of attention from the locals! We’ve seen lots of sponges, ranging in colour from white to bright yellow and orange.

The slight time delay on the digital camera and the motion of the camera in the water means that taking the perfect picture requires a mixture of skill and luck. It's important that the pictures are of good quality, to ensure that the animals and habitats can be successfully identified. This has led to a bit of friendly rivalry between the JNCC staff on board as to who can capture the best image. Watch this space - the winning image will be shown on the next blog entry!

In addition to using the underwater camera, we’ve also been taking grabs of sediment where possible. Once samples of sediment have been taken, the sample is then washed in a washing machine like sieve to washing away the finer sediment. The water pressure in the sieve seems to have a mind of its own, frequently splashing both the user and unsuspecting passers by!

The dayshift were surprised to find a “mermaid’s purse” in one of their grabs, which is the egg case of a shark or ray. The night shift found two small cup corals (Caryophyllia smithii) on a stone in one of their grabs. This species of stony coral is similar to anemones but produces hard chalky skeletons to support and protect their bodies.

Now that the ground-truthing has been completed, we’re back to collecting acoustic data for an additional section of the bank. We’ll continue with this until around 8pm this evening, when we will say goodbye to Pobie Bank Reef and begin our steam back to Aberdeen.

Monday 2 September 2013

Whale song!

Conditions have certainly livened up over the last 48 hours! The wind has been gusting up to 45 knots and lots of small birds have landed on the boat to shelter from the weather. Luckily the Scotia (and its crew!) are taking it well and we’ve been able to continue collecting data without problems so far.

It’s been over a week now since we left Aberdeen, and we’re starting to get a good picture of our survey site. The main section of Pobie Bank Reef is located at depths of 70 – 100m, and is made up of bedrock and large boulders, surrounded by a mixture of sediments. We’re currently collecting acoustic data in the third survey block, where we’ve detected some large, dramatic rocky outcrops. Previous studies of the site have mentioned these topographically complex areas, and we’re looking forward to putting the camera down to find out more.

The rocky reef provides a hard surface for a range of sea life to establish on, including communities of encrusting sponges and bryozoans. The cup-shaped Axinellid sponge (Axinella infundibuliformis), has been seen regularly during the camera tows. Other species commonly spotted include cup corals (Caryophyllia smithii) and the brittlestar Ophiura albida. We’ve also seen hermit crabs in abundance, several squat lobsters, and even had a ling (Molva molva) following the camera plum line on one of the tows. We’re not sure if he was curious or hungry!

As certain people onboard are very enthusiastic about Cetaceans (whales and dolphins), the bridge kindly called down to the office on Friday morning to let us know when four killer whales joined us right next to the ship! Unfortunately, the whales did not take into account that the day shift had just started a camera tow and were busy following a transect. Stuck in front of the computer in a windowless lab, the scientists desperately hoped that the whales would stick around long enough for them to finish the line. Having just finished work, the night shift were obliviously eating their dinner upstairs, until they spotted the others on the look-out. We were all too late, of course, and so none of us got to see the “pandas of the sea” this time. But we are, somewhat optimistically, hoping they might come back soon. Anything can happen at sea!