Ellen McCallie's Zanzibar diary: Shipwrecked

Production team

Day 1

Purifying water using the sea…that’s Mike’s and my challenge. But the water we were to purify into drinking water wasn’t sea water; it was water in a cistern-type thing. The concern was that bacteria and other living things would be in it.

I was a bit mystified as to what we were going to do until Mike started rattling off common chemical components of sea water…one of which is iodine. Thinking of the challenge in this way made it possible. Although the concentration of iodine in sea water is too low for us to extract it, some sea-weeds take up and store iodine. So instead of getting iodine directly from sea water, we could use seaweed, which has already done the work of collecting and concentrating the iodine in its tissues – no, I don’t know why it does this – anyone have access to the internet about now?

But how do Mike and I know that sea-weeds have relatively high concentrations of iodine? Health food stores often advertise sea weed as a good source of iodine, plus, somewhere along the line, I read that in the 1800s (I think that’s the right century…) that brown sea weeds were the major source for iodine extraction. Iodine was and still is important to human health as it is a necessary nutrient for the thyroid to work correctly. Look at the label on your table salt - it probably says “iodized salt” just to for this reason. Iodine can be added to table salt without much work and it doesn’t affect the taste.

But we are interested in iodine for its purification properties. Basically, iodine is effective against viruses, bacteria, and most protozoa, all of which can make us sick.

So Mike and I, along with Tony, the cameraman, Simon, the soundman, Rosie, the director, and Hisdory, the local expert on where to find stuff as well as the driver and translator, all piled in the car and headed off to the other side of the island. Though we were on the ocean, this side of Zanzibar wasn’t known for its seaweed.

One thing about looking for plants and animals, even if you know the general area where they should be found - based on habitat - that doesn’t mean they’ll be standing there waving at you. We spent several hours going from beach to beach, combing the water’s edge looking for brown seaweed. Thankfully the tide was out, otherwise we would have been swimming the entire time- a lot of fun, but not a very efficient way to cover a lot of coastline.

We finally found the stuff – various species of brown seaweed. We collected bags and bags of it because none of us had any idea of what concentration would be in the seaweed and how good our methods of getting it out without losing it would be.

Now you ask, why brown seaweed and not red or green or the clear/white seaweed? Basically, we chose brown seaweed because historically that’s what people extracted iodine from. Iodine is probably collected and stored in all seaweeds, but different kinds may take up different quantities. With only three days to do this challenge, we decided to trust those who came before us…use what they used. Otherwise, we could have collected a bunch of different kinds of seaweed, processed them all separated and seen which produced the most iodine per unit wet weight (or dry weight). Not enough time for that though…

Day 2

This was an odd sort of day. Mike and I set up for the iodine extraction process - fire and chemicals – but soon it was apparent that Kathy and Jonathan needed another set of hands to help with their challenges. As Mike’s the chemist and extracting iodine is chemistry, I headed off to help the other two, while still regularly supplying Mike with firewood.

In the late afternoon, we heard whoops and cheers from Mike’s area. A purple haze had formed – the colour characteristic of iodine. The quantity of iodine he’d extracted was incredible. I couldn’t believe it. It made me think that maybe any seaweed would do…or maybe brown seaweeds preferentially accumulate iodine…but we’d used several different species of brown seaweed…a lot to think about and try later…

At 10:30pm, Jonathan and I were still at work making modifications to his underwater rover and our call for the next morning was 5:30am…

So where do we all stay? As it worked out, Kate, Kathy, and I stayed at a house by the workshop, right on the ocean, about 3 km from a paved road, and about 30 minutes from Stonetown. Mike, Jonathan, Tony and Keith (the cameramen), and Simon and Rob (the soundmen), all stayed in a house in Stonetown. The production team stayed at a hotel about half way between us.

Day 3

Up at the crack of dawn. Normally, Kate, Kathy, and I go running or swimming in the morning followed by a home cooked breakfast-we take turns - but not this morning. We piled into the car and headed to the Stonetown docks. Hisdory, the local expert on the area, driver, and translator, couldn’t believe it was really necessary to get up this early in order to put the rover in the water-the water would be there all day and into the night? In fact, he’s completely right. It just takes a long time to get anywhere with 15 people, which includes scientists, Kate, the production team and the crews. Also, filming takes a while.

More importantly in this case, if we wanted the rover to take pictures of the shipwreck, we had to get there during low tide, otherwise it was likely that the watertight seals on the rover wouldn’t hold up to the pressure. A water-logged rover doesn’t work very well.

It got pretty amusing as Kathy was trying to find a tiny shipwreck in the middle of a huge ocean using just a couple of sightings. Who knows, we could have been off by only 10 or 20 meters, which is nothing considering the tools we were using, and not have seen the shipwreck. The wreck was too deep to see from above water and the visibility in the water wasn’t good enough to see very far in any direction. After diving a bunch of times, Kate said she’d found a nice patch of coral, but no shipwreck. With time quickly passing, we all decided Kathy had done great and Jonathan should go ahead and set up the rover to observe coral and fish. The rover worked pretty well, except for the fact there hadn’t been enough time to balance well. It tended to face straight down and fly. It takes a while for the rover to respond to a change in the controls, so one time it hit the bottom, but not coral, thankfully. That broke the camera in the front of the rover…that called it a day.

Kathy’s challenge brings up a whole lot of interesting issues. Can you pinpoint a precise location at sea by using several sightings on land? I thought it was a very interesting challenge, but there was no way she could succeed. By using sightings, how could she possibly find a shipwreck that wasn’t visible from the surface? Now, if her challenge was to find an island in a general area, no problem. Read Kathy’s diary about this…