Another successful survey aboard the Cefas Endeavour

We’ve now come to the end of our allotted survey time at North Norfolk Sandbanks and Saturn Reef SCI and were very lucky with the weather given the time of year! We have been gathering evidence on site now since the 5th November and have lost less than two days in total to unworkable conditions.

We managed to survey five areas in detail where Sabellaria spinulosa reef had been previously recorded , collecting 100% acoustic data in these blocks with accompanying video and grab samples. In some areas, it was very clear from the sidescan sonar signature that there was reef on the seabed. The image below demonstrates what I like to call a “mackerel’s back” pattern indicative of a well-developed reef in the centre (clearer in the darker areas).

Areas of suspected Sabellaria spinulosa reef to the west of Saturn Reef in the North Norfolk Sandbanks and Saturn Reef SCI (JNCC/Cefas 2013)

The images below were taken from some of the areas identified on the sidescan image above and demonstrate the type of reef that Sabellaria spinulosa can form. In order to determine whether the aggregation of worm tubes constitutes a reef feature, the extent, height and patchiness will need to be considered back in the laboratory.

 

Concretions of Sabellaria spinulosa tubes that will be assessed for “reefiness” when back in the laboratory (JNCC/Cefas 2013)

The presence of live Sabellaria was confirmed by taking samples from the seabed, which can also give an idea of the scale of the worm tubes. Some tubes, such as those in the image below, were well in excess of 10cm.

Sabellaria spinulosa worm tubes sampled using a Hamon grab (JNCC/Cefas 2013)

We also managed to take 85 Hamon grab samples from across the sandbank features and map the profiles of the sandbanks using multibeam. Given that the draft of the Cefas Endeavour is 5m (or 6.2m with the multibeam blade down) and that some of the sandbanks are less than 7m in depth, we had to be very careful when sampling the crests of the banks to ensure we didn't get stranded!

A processed Hamon grab sample ready to be preserved in formaldehyde (JNCC/Cefas 2013)

I'd like to say a big "thank you" to Paul Whomersley for all his hard work during the cruise and shift leads Chris Jenkins and Joanne Murray for keeping the scientists motivated. Once again, the Endeavour scientists and crew worked around the clock to ensure we gathered all the data that we needed to.

Gareth Johnson

The End is Nigh

Hello again from the Cefas Endeavour, where we are currently making good our getaway from North Norfolk Sandbanks and Saturn Reef SCI. Our time at this site complete, we are now steaming south towards the Thames Estuary to another site, from where we will be working for the final few days of this research cruise.

So what have we learnt from our time at North Norfolk Sandbanks and Saturn Reef SCI? Last week I described our two objectives for this survey- to try to find evidence of Ross worm (Sabellaria spinulosa) reef in the site and to see whether biological communities found in different seabed habitats within the site are statistically different from each other. While a lot of work remains to be done back in the lab to process and interpret the data we've collected, we have been encouraged by the amount of potential Sabellaria spinulosa formed reef observed on this survey, both in the sidescan sonar data and the grabs and camera tows collected, as well as some of the other critters we've come across.

Up close and personal with a potential biogenic reef formed by Ross worm (Sabellaria spinulosa) tubes (JNCC/Cefas, 2013) 

Dahlia anemone Urticina felina nestled in sand with hydroid species and Sabellaria spinulosa formed tubes (JNCC/Cefas, 2013) 

We have also collected grab samples from the troughs, flanks and crests of many of the sandbanks. Sample locations, or "stations", were chosen to include landward and seaward facing sides of the sandbank, as well as inshore and offshore locations. The samples collected will enable us to make comparisons between the communities living in and on the seabed at these sites. Some of the animals that form these communities can be seen below.

(Top) Sieve containing seabed sediment and associated fauna, including the Serpent brittlestar Ophiura ophiura, (Bottom) Masked crab Corystes cassivelaunus (JNCC/Cefas, 2013)  

Completing this work has very much been assisted by an improvement in our weather over the last few days (see below picture, and feel free to compare with the previous post's view from Beccy's cabin window!). And, of course, the work would have been quite difficult without the hard work and expert knowledge of our Cefas partners (not to mention their ship, our survey platform and home for most of this month!).

Leaving site (Joey O'Connor, 2013)

Weather up, surveyors down

Unfortunately Wednesday and Thursday have been bad days on the boat as we are down on weather. High winds and choppy seas mean that we cannot deploy the camera or grab equipment safely (for proof of the conditions see the photo below of my cabin port hole.) Conditions were even too rough for the sidescan sonar as the device was moving too much in the water column creating poor quality data. As good quality sidescan data is critical to identifying areas of Sabellaria, we have also stopped this operation for the time being. We have spent this time collecting some additional multibeam data to improve our knowledge of the sandbank bathymetry and we are hopeful that we will resume grab sampling later on today.

A wave hits my port hole on the lower deck (Rebecca Oliver/ JNCC). 

I thought I would take this opportunity to talk about the day-to-day operations of scientists on the vessel. The scientists generally work in one of 3 places: the plotting room, the dry lab or the wet lab. Joey mentioned the plotting room in the previous blog, which is where all the acoustic data is observed and cleaned, so I will focus on the laboratories where work is more hands on.

Dry Lab (Rebecca Oliver/JNCC)

The dry lab is located next to the side gantry so we have quick access to where the equipment is deployed, such as the drop camera and Hamon grab. In the photo above, Julia is sat in the “hot seat” from where she can watch the vessels movements and advise the captain on the next station. She also notes down the position of the vessel when each piece of equipment is being used (these are known as fixes). This positional information is essential in order for us to match our acoustic data and biological samples with an accurate position on the seabed. From this room we are also able to watch a live stream of the video from the drop camera when on the seafloor. Another member of staff is in charge of taking still photos, whilst watching the video feed, but getting a good image is a real skill as there is a small delay between pressing the button and the shot being taken so you have to have quick reactions (or be prescient).

The wet lab is, like the name suggests, where the wet, mucky work happens. Here, we store the sieved grab samples we bring on board and prepare them for later analysis. Before they come inside, they are sieved through a 5mm and 1mm sieve on deck. This separates out any macrofauna species (>1mm) living within the sediment which we then preserve for lab analysis once we are back.  We also keep a separate sample of the sediment so we can measure the size and distribution of the component particles: this is known as a PSA sample (particle size analysis).

Stage 1: Jo Murray and Linford Mann deploying the grab (Rebecca Oliver/JNCC)

Stage 2: The Hamon grab sample once removed from the grab, prior to sieving (JNCC/CEFAS). 

Stage 3: The sample is washed through two sieves; firstly a 5mm sieve (above), then a 1mm sieve (right). In this sample we found a sea potato, an Echinoderm that lives buried in the sand and is covered in hair-like spines (JNCC/CEFAS).

Signs in the Sand

Hello again from North Norfolk Sandbanks and Saturn Reef Site of Community Importance (SCI), where our survey efforts are continuing.

As Beccy mentioned in Monday's blog, the day shift have been spending most of their time collecting grab samples and video tows, while night shift duties have tended to focus predominantly on acquiring sidescan and multibeam sonar data. My night shift colleagues and I have been assured that this is a result of the survey design and the influence of changing weather patterns (both of which affect which survey methods we employ at any given time), and that we would be foolish to consider it a conspiracy... What we can say with certainty is that this has meant that while the day shift have been carrying out the more "hands on" bits of work, we've been based in the Plotting Room, where we've been collecting acoustic data to help inform groundtruthing.

Cefas scientists Chris Jenkins and Paul Whomersley  interpreting acoustic data in the Plotting Room (Joey O'Connor, 2013) 

The idea behind using acoustic data to inform our groundtruthing efforts is based on the theory that Sabellaria spinulosa reef can be detected from sidescan sonar. A recent paper discussing this can be found by following the link. For information on how sidescan sonar works (and, indeed, what it is) please refer to this document, produced by the Mapping European Seabed Habitats (MESH) project.

As different substrates reflect sonar waves differently (much like a ball dropped on concrete will return further than a ball bounced off mud or sand, all other things being equal), we are hoping to identify the unique acoustic "signature" that reef formed by Sabellaria spinulosa has. Therefore, as we collect the data we check them for possible Sabellaria reef signatures. We then take note of locations where we've seen a potential reef signature. These locations are visited, and we carry out camera tows and grabs to see what is actually on the seabed.

Gas platform (Joey O'Connor, 2013)

In other news, it has been a quite surreal survey working amongst the myriad oil and gas platforms in this part of the world. Attached above is an example of one we passed yesterday. Further images and information on these installations can be found in a recent blog written by our Scientist-in-Charge for this survey, Cefas stalwart Paul Whomersly, who has also been blogging throughout the survey.

Hunting for Sabellaria spinulosa

Five days at sea and data collection is currently going well. We have had one period of bad weather which stopped surveying for 12 hours, but we all made it through to the other side. So far, the night shift have been collecting most of the information on the bathymetry of the seabed through sidescan sonar and the day shift have been collecting underwater video footage and grab samples of the seabed sediment and associated species.  We are utilising a sidescan sonar towed behind the boat as it enables us to distinguish between Sabellaria spinulosa reef and surrounding sediment from the different acoustic signatures of the two substrates.

If you have read the previous blog entries from this survey, you will already know that we are particularly interested in finding Sabellaria spinulosa (Ross worm). We have continued to find evidence of this species and in one grab sample we found reef that the worm had constructed, which looks like honeycomb made of sand (though the "honeycomb worm" is actually the common name of another species in this genus, Sabellaria alveolata). We broke the sample apart to check that it was occupied by the worm, which, in this instance, it was.

A cross-section of some Sabelleria spinulosa reef with worms occupying some of the holes (JNCC/CEFAS). 

Photo showing how Sabellaria spinulosa forms a reef allowing other species to thrive, such as this common starfish (JNCC/CEFAS). 

Sabellaria spinulosa reef forms solid structures out of the otherwise flat seabed creating shelter and hiding places. What species can you find in this photo? (JNCC/CEFAS)

We have now moved further south within the North Norfolk Sandbanks and Saturn Reef SCI to an area which is surrounded by gas platforms. On route to this new area, we took the opportunity to practise emergency drills and on this occasion a dummy was thrown into the water and “man overboard” was announced over the tannoy. We all assembled quickly at the muster station and took up lookout either side of the vessel as the captain turned the vessel around and the crew launched the workboat. It is reassuring to know that these skills are kept up to scratch and how well the crew all work together as a team.

 The Endeavour workboat returns to the vessel after rescuing a dummy during the “man overboard” drill (Rebecca Oliver/JNCC)

Sandward Ho!

Greetings from the Cefas Research Vessel (RV) Endeavour, where we are currently undertaking the second leg of our seabed survey of the North Norfolk Sandbanks and Saturn Reef Site of Community Importance (SCI). Further information on the site can be found in the previous blog, as well as on our website (www.jncc.defra.gov.uk).

With about half of our survey party having just spent a week out here, we returned to site in the wee hours of Wednesday morning with a good idea of what lay in wait for us- lots of sand! This has so far turned out to indeed be the case, though we have observed fine (i.e. muddy) and coarse (i.e. gravelly) sediments accompanying the sand in some of the samples and video tows collected. Fauna potentially seen so far include the bryozoan Flustra foliacea,  the Dead Man's Fingers coral Alcyonium digitatum, assorted sponges, starfish, brittlestars, hermit and swimming crabs and some fish species, including dogfish, sandeels and plaice. I say potentially as the above species have been "identified" via a live feed from a camera positioned above the seabed to a moving vessel full of over excited scientists- the data will be fully analysed and species confirmed (where possible) back in the relative comfort of the lab.

Alcyonium digitatum and anemone (JNCC/Cefas, 2013)

Sand eel, Ammodytes sp., in the 1mm sieve once the fine sediment had been sieved through (JNCC/Cefas, 2013)

We have also seen Ross worm (Sabellaria spinolosa) tubes, which provide a surface for other species to attach and can increase species abundance in sandy sediments. Biogenic is defined as "produced by living organisms or biological processes"- in the case of the Ross worm, tubes of sand are formed which can clump together to form biogenic reefs which protrude from the seabed. These give a hard substrate with nooks and crannies for other animals to attach onto and live in, and as such function in a similar manner to coral reefs or a rocky seabed.

Sabellaria spinulosa tubes with the starfish, Asterias rubens (JNCC/Cefas, 2013) 

Our objectives on this survey are twofold. Firstly, we are trying to find evidence of Ross worm reef in the site, as biogenic reef habitats (including those formed by the Ross worm) are listed as being of conservation importance by the EU Habitats Directive (http://jncc.defra.gov.uk/page-1445). Secondly, we hope to ascertain whether infauna communities found in different habitats within the site are statistically different from each other. To achieve this we are aiming to collect a sufficient amount of data from three different depth zones identified before the survey: sandbank troughs, flanks and crests. Answering these types of questions is paramount to understanding the relationships between biological communities and the environments that they inhabit.

To date we have been concentrating on the first objective, as well as enjoying some very nice sunrises.

Sunrise (Joey O'Connor, 2013)

North Norfolk Sandbank and Saturn Reef SCI site survey

JNCC has recently completed a lead scientist training cruise hosted by Cefas aboard the RV Cefas Endeavour. The survey was staffed predominately by JNCC staff, with support from senior Cefas and JNCC scientists and the ship’s crew. The aim of the survey was to train JNCC marine staff up to a level where they could lead future JNCC seabed surveys.

JNCC and Cefas scientists who led and participated in the training cruise. 

Bottom row (l to r): Bill Meadows, Joey O’Connor, Neil Golding, Declan Tobin, Koen Vanstaen; Middle row: Oliver Crawford-Avis, Megan Parry, Laura Robson, Fionnuala McBreen, Nigel Lyman, Laura Cornick, Julia Rance, Sue Ware; Back row: Mike Nelson, Paul Whomersley, Mark Whybrow, Gareth Johnson

Neil Golding and Mike Nelson donning their survival suits during an early muster drill

The training was carried out on the first survey leg of the North Norfolk Sandbanks and Saturn Reef Site of Community importance (SCI). The vessel returned to Lowestoft on the 12th November to swap off some of the JNCC staff for Cefas scientists and then the vessel will return to site. Two JNCC staff will join the second leg of this survey. The SCI is located in the southern North Sea and has been designated under the Habitats Directive for Annex I sandbanks and biogenic reef.  The North Norfolk Sandbanks themselves are a series of ten main sandbanks and associated fragmented smaller banks formed as a result of tidal processes and Saturn Reef is a biogenic reef formed by the polychaete worm, Sabellaria spinulosa.  The banks support communities of invertebrates which are typical of sandy sediments in the southern North Sea such as polychaete worms, isopods, crabs and starfish. They extend from about 40km off the north-east coast of Norfolk out to approximately 110km.

Site bathymetry showing the distribution of sandbanks

Sabellaria spinulosa biogenic reef, is a fragile structure, comprising thousands of delicate sand-tubes made by ross worms (polychaetes) which have consolidated together to create a solid structure rising above the seabed. Last week, during the training survey, a number of areas of S. spinulosa were identified, which will now need to undergo assessment to see whether they meet the criteria for reef.

Suspected Sabellaria spinulosa reef sampled during the CEND22_13 survey to North Norfolk Sandbanks and Saturn Reef SCI

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

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.

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!

Sea Sea TV?!

Our progress has gone well over the last few days which has been helped by the good weather! The sea has been kind to us, which has made our job much easier. Whilst processing grab samples on Tuesday night, the day shift was treated to a beautiful sunset over Shetland in the far distance, and the night shift got to see the sun rise the following morning.

Finally, the acoustic work for box 1 has been completed!! The data has been used to identify 18 ground-truthing stations distributed throughout the box. Ground-truthing usually involves towing a camera just above the seafloor, which transmits a live video feed back to the ship showing us the different species and habitats that are down there. We’re also able to see how the seabed changes within and between stations, from sandy sediment to boulders and bedrock; it keeps the camera operator on their toes as big rocks often loom out of the darkness with no warning!

As well as collecting video, we also take regular photographs to help with identifying the animals we find. So far, we’ve seen several species of fish, including a well camouflaged monk fish, as along with an assortment of sponges, sea urchins, anemones and plenty of impressive starfish. This has started a competition between the scientists on board as to who can take the best photo!

If we find areas of sediment on the seabed, we may also collect samples from it using a grab. The stuff we scoop up can be analysed to determine exactly what type of sediment is present and also to identify any animals that like to burrow into it. But more about this in a future entry!

Now that the 18 stations have been completed, we have moved on to section 2 and have started to collect more acoustic data. The weather charts are showing lots of bright colours over the weekend, which generally means that stormy conditions are around the corner. We are trying to get as much data collected beforehand as possible, whilst also hoping that the forecast turns out to be wrong!

Sounds of the seabed

Since reaching Pobie Bank Reef cSAC on Saturday lunchtime, we have been focusing on collecting acoustic data using sidescan sonar and a multibeam echosounder. These data provide information about the seabed; sidescan uses diagonal sound waves to identify features on the seabed, whereas multibeam measures the depth of the seabed and collects 'backscatter' data which give an indication of the hardness and roughness of the seafloor.

Multibeam data

The data are collected in ‘swathes’ using sensors that are fixed to the ship's hull or pulled behind it on a torpedo-like 'towfish'. The sidescan has been collecting some interesting data so far, the detail in the images has allowed us to make out rock formations, different sediment types and even underwater pipelines!

The towfish out of the water

The towfish being deployed

We’re currently in the first of three survey sections, which is a 50km long rectangle where a single tow can take up to five hours! We hope to complete the acoustic work for this section later today. After the data have been processed by our colleague from the British Geological Survey, we can use some of the outputs to help inform where to focus the groundtruthing work.

Today the clouds have lifted slightly, but it's still very grey! This afternoon we’re due to collect another of our Marine Scotland Science colleagues from Shetland so we may even get a rare glimpse of land...