Friday, 22 November 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).