Friday 31 August 2012

Diverse marine habitats

After a busy weekend of multibeam, a low pressure weather system moved in and
the Pole Star was forced to head back to Oban to shelter. This gave us time to
back-up and examine the data we had collected during the previous week.

Based on multibeam data that Gill and Kirsten (BGS) processed on board, we
were able to select locations for sampling. Groundtruthing is an important part of
the survey as it allows us to assign particular habitats to corresponding areas of
multibeam. The two pieces of equipment we are utilising for this purpose are a
drop-camera and Day grab. The drop camera allows us to take videos and
high-resolution stills of organisms living on the reef or projecting from the
sediment, whilst grab samples of sediment allow us to extract organisms from
within. Cefas are providing technical support and expertise in the form of Simon
and Jo to assist with the groundtruthing.

Stanton Banks SCI is proposed for designation because of its Annex I rocky and
stony reef habitat. Through use of the drop camera, we now have information on
the types of species that live on and around the reef. From images collected so
far, we have seen various types of crab, starfish, featherstar, sea urchin and sponge.

Brittlestars (Ophiocomina nigra)

Edible crab (Cancer pagurus)

Featherstars (Leptometra celtica) and squat lobster (Munida rugosa)

We have also found muddy sediments around the reef features. Though there are
 fewer conspicuous species on the surface compared to the rocky areas, we have
seen a number of sea pens and nephrops.

Sea pens (Funiculina quadrangularis) and langoustine (Nephrops norvegicus)
We are currently heading for a crew change before transiting back out to Stanton
Banks to try and finish the survey in a good weather window between gales.

Tuesday 28 August 2012

A lesson in multibeam acoustics

Last time I mentioned that we were anticipating some bad weather. When it finally hit
we had to batten down the hatches and take shelter moored on the beautiful Isle of
Barra overnight. We managed to go ashore whilst the vessel took on fresh water,
stock up at the local shop, and make a visit to the local pub.

We are now back collecting multibeam data over the southern section of Stanton
Banks SCI (Site of Community Importance). Our BGS colleagues have written a
paragraph to explain a bit more about their work:

Hydrographic surveyors “look” into the ocean to see what the sea floor looks
like. A multibeam echosounder is a device typically used by hydrographic
surveyors to determine depth of water and the nature of the seabed. On the
Polestar, we use a Simrad EM3002D shallow water (0.5-160m) high resolution
multibeam system. This  system collects a swath of bathymetry data that is up to
10 times the water depth wide. By running survey lines correctly spaced apart,
very accurate 100% coverage of the water depth can be collected. Data is
processed onboard using Caris, taking into account position, ship motion etc.
The final product is displayed using 3D viewers to fly through the data as if
the water were not there. The images BGS produce can then be used to aid
JNCC and CEFAS scientists in determining the best locations for camera tows
and grab sampling.
Kirstin & Gillian

On a closing note, this morning we saw dozens of common dolphins jumping in the
wake of the ship and spied a pod of about 150 out in the distance. I also saw my first
ever minke whale this afternoon as well!

Becca Lowe

Tuesday 21 August 2012

Playing with Mud

After a couple of days of multibeam to the north of the Stanton Banks site, we got to do some biological sampling. We conducted five video tows and two grab samples from areas of interest detected in the multibeam images. On one camera tow over rocky reef, we observed hundreds of small prawn cracker sponges, Axinella infundibuliformis (see image), encrusting the rocks. On other tows, we saw areas of burrowed mud, with seafans and evidence of Nephrops norvegicus. The two grab samples we collected were both of muddy sediment, which have now been sieved and preserved ready for analysis. It was my first time doing grab sampling, hence the cheesy photo with the Day grab! We use a Day grab to sample finer sediment as it tends to disturb the sediment less during collection.

We are now back to using multibeam for the next couple of days over the larger south-eastern portion of the Stanton Banks site.
There is a large area of low pressure heading towards us over the next couple of days with some murmurs of swells reaching up to 2.5m so there is some trepidation about that!

Becca Lowe

Sunday 19 August 2012

A Rough Start

Stanton Banks are a series of granite rises which outcrop from the seafloor south of the Outer Hebrides (approx. 124km west of UK mainland). Stanton Banks was designated as an SAC in 2008 and has now been accepted as a Site of Community Importance. Five surveys have been conducted on Stanton Banks, which confirm the presence of Annex I reef. The aim of this survey is to acquire further information on the presence and extent of Annex I reef and additional data to help develop a baseline for future monitoring of the site.
After a couple of small teething problems (including electrical failure onboard the vessel) leading to a minor delay to the survey departure, we have finally set sail bound for Stanton Banks. We departed Oban at 1300hrs on Friday 17th August and sailed through calm seas to arrive at Stanton Banks at 2200hrs. The Pole Star is proving herself to be an incredibly rocky ship even with very little swell of just 1m. Acclimatising to this is proving to be a challenge in itself but all in all, we are all in ship shape.
I should mention who 'we' all are: Gareth Johnson and myself (Becca Lowe) from JNCC, Simon Pearson and Jo Murray from CEFAS and Kirsten Crombie and Gillian Horner from BGS. BGS are currently hard at work using acoustic techniques to measure bathymetry of the seabed so that we can decide where best to take video and biological samples.
On a less technical note, the food is top notch (if you can manage to keep it down!) and I also spotted a pod of common dolphins yesterday evening and this morning jumping beside the vessel. I didn't have my camera with me at the time but hopefully some wildlife pictures to come....
Becca Lowe