Posted by: keepfishing | May 23, 2008

A Reason for Being [in Zanzibar]


Some avid readers have repeatedly asked for an explanation of what I’m doing out here in Zanzibar. So, loathe to disappoint the masses (or the one guy who asked twice), here is a rationale for two months in Stone Town, with (most) of the sciency bits taken out.

As many of you know, I’m currently enroled  on the Tropical Coastal Management MSc at Newcastle University. The structure of the course means that from September to March, we get taught lots and lots and lots of theory and complete the associated coursework, and then from April-July, we’re expected to go somewhere tropical (the more astute amongst you may have noticed Newcastle isn’t exactly flush with coral reefs), and conduct a novel research project.

Armed with this commission, I have ended up in Zanzibar studying coral diseases. Actually, they’re not diseases – we have to call them syndromes  – because we can’t be sure of the bacterial/viral cause unless we do some microbiological analysis, but that’s a little too technical.

A bit of background to disease in corals: Currently, there are around 37 different diseases/syndromes that have been described globally. Each has a nice set of ‘classic’ signs that distinguish it from another; I even have a World Bank ID key that tells me how common diseases might be mistaken for another. 

Unfortunately, disease identification (unless done microbiologically) is not like identifying a species. With speciation, you can look at a bird, or a fish, or a bear and look to see whether it has a white stomach, or a red fin, or ears bigger than its paws. With diseases, it is much harder. In humans, there is the advantage of the afflicted (usually) being able to talk. A doctor can ask what hurts and the patient can accurately describe the specific symptoms that might make diagnosis possible.

Corals can’t talk. We’re left with what we can see, how the disease expresses itself, which, unfortunately occurs accross a huge gradient. For starters, the same disease can manifest itself quite differently accross different coral forms (e.g. branching, boulder, table) and secondly, visual indicators often occur across a gradient – some symptoms are there, whilst others are not. The long and short of it is, whilst you often come across coral colonies exhibiting ‘classic’ symptoms of disease, you equally discover many colonies across the gradient.

So what to do with the ‘unknowns’? Do we look hard and try and force them into one of our predefined bins, making a decision on whether it is ‘white pox’ or ‘white plague’? Or do we classify them as unknown? Largely, the scientific community has apparently forced such specemins into diagnostic bins, or at least we must assume so, as i’m yet to discaover a scientific paper that has an ‘unknown’ category. Papers also exist that describe the prevalence of a disease such as ‘white pox’ in a specific area, without ever describing how they are categorising ‘white pox’ and leaving us with an unrepeatable study.

The significance for all this is that coral diseases are bad (responsible for the first shift in types of common corals in over 7000 years in the Caribbean), and if we misunderstand which diseases we’re working with, it is very easy to prescribe the wrong type of management solutions and produce years of ineffective effort.

So, if you’re still with me, the point of my project is to try and look at lesions (bits that shouldn’t be there) on corals in Zanzibar, and come up with definitive definitions for coral diseases here, based on actual sampling of what is really out there. Basically, I snorkel and dive at as many places as possible around the island, and take pictures of ‘ill’ corals. The idea is that hopefully, I will have seen pretty much ever manifestation of diseases that exist here, which then are described in a complicated matrix, which produces even more complicated diagrams (see below). Ultimately, I end up with groups of similar lesions, which I can then classify as the syndromes present here.

Right now, I’m nearing completion of the data collection. I have to run a couple more dives where I measure disease prevalence (percentage individual corals are actually infected) and the diversity of corals, at a couple of sites, and then collect a load of environmental data so I can look at whether more polluted sites have more infections. But, essentially, I’m almost there. The hard part starts at home when the hardcore analysis and paper writing begins.

But before then, there is the small matter of climbing Kilimanjaro…




  1. hey so when you have a show on discovery channel someday, can you get an autograph from mike rowe or bear grylls for me please? both would be ideal. cheers!

  2. this was very understandable…well done.

  3. i find that truth often has many layers and works on many levels. Whilst the above is obviously true, i suspect it is equally true that the reason for being in zanzibar has to do with beautiful beaches and gauranteed sunshine…

    now why didn’t i pick a career that involved spending large chunks of time in the tropics and calling it work.

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