R/V Pelagia 2009 Day 1: The day of the landers

Today marked our first day of work on the HERMIONE/CoralFISH cruise; these overlapping projects focus on areas of biological wealth, which have either high numbers of species or rare species associated with a distinct area. These areas have been referred to as ecosystem hotspots and are sites of interest from both biological and conservational standpoints. The role that they play must first be understood before they can be effectively preserved.

We sailed from Galway at 2pm yesterday and arrived at Belgica mound in the early hours of this morning. This area was studied last year and found to be an area rich in cold water corals. The footage that was captured proved popular with the local media and public interest was captured in Ireland’s previously unknown coral reef.

Once on site we conducted a quick multi-beam survey of the area: this is essentially bouncing sound off the seabed and using the echo to form a three dimensional map of the area. The undersea mountains of this area are small and distinct. To effectively place our equipment we first needed an accurate map of the area to work from. Once that was completed we lowered the CTD (measuring conductivity (from which salinity can be calculated), temperature and depth). These factors are some of the most basic environmental conditions but also some of the most significant when it comes to what organisms are found in an area. The CTD is also equipped with a rosary of bottles. This is a ring of 24 sampling bottles that can be triggered at desired depths to bring water back from that layer. This water can then be subjected to more detailed tests such as nutrient content and amount of particles suspended within the water.

Once the CTD was complete I had my first opportunity to launch the lander (see photo) that I have been working on over the last few months. This will be used to compare the megafauna (large animals like fish and crabs) both on and off the coral mounds in the hope of identifying how these communities differ. The lander is basically a time-lapse camera looking down at some bait. A CTD and current meter is also attached. The current meter lets us estimate how far the smell of the bait has spread and, coupled with how many fish are seen in the image, allows us to make estimates of the number of fish in the area. Once the lander has collected this data, taking something between 12 and 24 hours, it is remotely commanded to release its ballast and surface.

Deploying a piece of equipment in this way for the first time can be a very stressful experience. You have to trust that you remembered to do everything right and then release it to fall to the seabed. Did I calculate the ballast and buoyancy correctly? Did I start everything recording? Did I close all of the watertight housing properly? Will the ballast hold? All of this is going to go through my mind tonight and it won’t ease until I have everything back on board and checked over, only to do it all again some hours later.

My worried were eased by a very smooth deployment. The crew of the R/V Pelagia are very experienced with this sort of deployment and I was happy to relax and trust the equipment to people far more experienced than me.

Later in the afternoon saw the deployment of the BoBo lander and the Albex Video lander. Deploying gear like this as soon as possible is not only time effective but also clears deck space for the processing of samples brought up from the bottom.

The hope for tomorrow is to recover two of these landers and quickly re-deploy them. There is some bad weather coming our way and they are actually safer on the seabed collecting data than up here feeling sick with us!

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