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Learning from the ‘sentinel speices’

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The crew and research team on-board the 72ft

Sea Dragon expedition ship are currently undertaking two expeditions from the Island to find out more about the Sargasso Sea.


Sea Dragon is operated by Pangaea Explorations, and has sailed around 50,000 miles over the last two years as part of a series of research expeditions in the Atlantic and Pacific Oceans.

During the missions the team are sending a daily blog, with photographs, explaining what they have been doing and what they have found.

Here is the most recent update from the

Sea Dragon.

Blog from Olivia Drescher:

Macroalgae, including Sargassum, are used as “sentinel species” in the biomonitoring of heavy metals of anthropogenic origin because of their abilities to accumulate contaminants from surrounding waters. Among these contaminants, mercury is a known toxin to humans. This January, the Minamata Convention on Mercury was signed with the aim of limiting global mercury pollution, thereby reducing the negative environmental and human health impacts of this metal. Despite global concerns about heavy metals, little research has been done to measure these contaminants in the Sargasso Sea.

This three-day research voyage aboard the

Sea Dragon was an incredible opportunity to collect samples for baseline measurements of heavy metal concentrations in Sargassum macroalgae sampled from the proposed “Blue Halo” marine protected area.

As we set sail on day one, after having met the crew and been shown our bunks, my mind drifted one last time over equipment I might have potentially forgotten to pack for sampling. GPS … check, ziplocks … check, waterproof markers … check, gloves (to handle sargassum, so that zinc from sunscreen does not contaminate the samples) … check. Oh oh … forgot seasickness meds.

Early the first afternoon, we spotted our first mat of Sargassum, and it was quite literally a gold rush on board for the rest of the day! Two of us with pole nets, a couple of spotters at the bow yelling directions to the person at the helm, and everyone else with buckets ready to sample the golden seaweed.

After chumming the water from a delicious pasta dinner (I got seasick after all), and a midnight to 4am watch, day two started in the wee hours with a plankton tow. Although it was a slightly rough start, I really enjoyed the day. We encountered a couple of big Sargassum rafts, the sampling was going well and I was able to take time to look at the unique marine life inhabiting the floating Sargassum from what the other scientists on board had been collecting. With the microscope set-up below deck (and my seasickness gone) I observed plankton as well as a whole array of different organisms specific to the Sargassum habitat. Heavy metals, at elevated concentrations, can harm biota and reduce biodiversity. This was a priceless experience, in the sense that I was able to take a personal firsthand look at this ‘biodiversity’ that we try and protect from harm.

As we regained sight of the Island again on day three, I knew that this short trip had provided me with invaluable practice and experience that in the long run, I hope, will make me a better scientist.

Taking another sample not required from the Manta Trawl
Olivia Drescher rinses the sargassum in a solution of Mili Q (distilled water) and wears gloves to prevent contamination. Judith Landsberg records the GPS co-ordinates while LaKai Dill observes
Bagging up another batch of sargassum
Rinsed, bagged and ready for analysis

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Published June 03, 2013 at 9:00 am (Updated June 02, 2013 at 5:18 pm)

Learning from the ‘sentinel speices’

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