Science at Sea » Field work

Creativity in the field

Jessica Carriere-Garwood — Thu, 13 Jun 2013 15:20:59 +0000

Being in the field or at sea is one of the perks of being an oceanographer, at least for some of us. To ensure that everything goes smoothly, a lot of planning and preparation comes into play because, just like camping, what you have with you is all you have and nobody wants to carry around more material than needed.

Anyone who has gone in the field regularly, however, will tell you that no amount of planning will prevent the unexpected from happening. This is when creativity can make or break an experiment. One instance when creativity proved to be useful was on a recent research expedition on board the RV SONNE. After almost 7 weeks at sea, sampling supplies on ship were running low. To sample sediment cores, cut-off syringes were used to draw some sediment and were then capped. Unfortunately, we ran out of caps and cores were still being collected.

As I was thinking of a simple way to cap the syringes without contaminating the sediment with the glue from the tape, it occurred to me that lab gloves ought to be made of material that would not contaminate the samples. We ended up cutting the fingers of some lab gloves (we had plenty of those), in order to pull them over the syringes and secure them with tape. This was simple enough and served our purpose!

The true syringe lid on the left, the improvised lid on the right.

Instrument recovery using acoustic releases

Chloe Malinka — Fri, 03 Aug 2012 15:20:13 +0000

In July 2012, I had the opportunity to conduct fieldwork in Grand Passage, Nova Scotia. This tidal channel lies between Brier Island and Long Island, along the Digby Neck, and is proposed for in-stream tidal turbine development. We collected acoustic measurements from a bottom-mounted frame with a hydrophone on it.

The greatest moment of suspense every day was when we had to recover the frame. This could only occur during the short time window of low slack tide, as the currents were too great to safely recover at any other time. To recover, an on-board instrument sent an acoustic command to the releases on the frame, and this initiated electrolytic erosion on a hoop of metal. The corrosion of the metal hoop set loose a bungee chord that held down a buoy, causing the buoy and line to float to the surface, and allowing for the frame to be hauled up. However, the buoy may not always surface; signals may not be have been effectively received, the batteries on the releases may have died, or shell hash could have lodged the buoy.

If the frame was not successfully recovered, there could have be delays in field plans, we would have had to hire SCUBA divers to manually release the buoy, or, in the worst case, we could have lost our expensive hydrophones (oh no!). It was always a great relief when the yellow buoy was spotted!

Moment of suspense while we wait for the buoy to surface

Sampling mud flats despite large tides!

Jessica Carriere-Garwood — Mon, 09 Jul 2012 21:00:27 +0000

You might have heard that the Bay of Fundy is home of the largest tides in the world, reaching heights above 16 m. As part of my Master’s project, I needed to obtain sediment cores from mud flats that experience such huge tides. Our usual hand coring technique consists of using a simple device to push plastic barrels into water-covered sediment, seal them, and bring them out. It is usually carried out from a small ship or even by simply walking into the water (see left picture below). This technique, however, was completely useless in the Bay of Fundy! Instead, we set up two semi-permanent pier that allowed us to walk over the mud without disturbing it and manually dig out our cores at low tide (see right picture below).

As you can see, my supervisor Paul Hill is not one to shy away from heavy work!

Usual hand coring technique.

Hand coring in the Bay of Fundy