Charles on Chagos

A team of scientists are coming to the end of an expedition to the Chagos archipelago in the middle of the Indian Ocean. It’s the first full scientific expedition to visit the area since the islands and reefs were declared a no-take marine protected area in April 2010. These are without a doubt some of the most spectacular and healthiest coral reefs left on the planet.

Before he waves farewell to the archipelago once more, we caught up with expedition leader Professor Charles Sheppard to find out more about these incredible reefs. Here’s part 1 of our exclusive Seamonster interview – watch this space for part 2 and more stunning photographs later in the week.

Helen – How did it feel to get beneath the waves in the Chagos again?

Charles – It is always terrific to get back in the water in the Chagos archipelago. My last dives here were a year ago because I’ve come here every year for several now.  My first visit was in the 1970s but started regularly researching here about 15 years ago.

In contrast to reefs in many other parts of the world where I work, these reefs simply magnificent. They have such high coral cover and such extremely abundant fish – much more than you would see in those parts of the world where coral reefs are exploited. Sadly, it appears that reefs do not need to suffer from very much use before they become over exploited and start showing symptoms of degradation.

These reefs are thriving and teeming with life, and the water is commonly very clear indeed.  Wherever you are in this archipelago, diving on these reefs is wonderful.

Helen – Were there any big surprises for the expedition?

Charles – I think all members knew what to expect in that they had heard several of us describe Chagos and they had all read many of the science papers that have resulted from our past work there. Even so the number of variations of the word ‘wow!’ as scientists surface from their first dive in Chagos is very high, and is always gratifying to hear!

You might have heard or read that fish are at least an order of magnitude more abundant than elsewhere, for example, but that is difficult to visualize it until you see it. The large number of huge grouper for example, which approach you to within 1 m, is simply not imaginable anywhere where there is fishing.  The word thrilling rather than surprising is probably a better word.

Helen – How are the Chagos reefs doing?

Charles – The reefs are thriving. In 1998, there was massive mortality of corals throughout the Indian Ocean, and this affected Chagos reefs as much as any others.  Rising temperatures was the cause. But in the case of Chagos, recovery has been rapid. Where reefs around the Indian Ocean are fished, and where they suffer from pollution and other impacts, the story has been not as good.  Sometimes they have not recovered at all and sometimes they have recovered only a little bit.

Here though, recovery has been perhaps better than has been seen anywhere else. We have tried to use the same kind of measurements each year when we can, and we have noted some interesting points.

After the massive die back that we saw happen in 1998, several years passed before anything visibly started to recover, in terms of corals and soft corals at least. When things did start to recover, corals in shallow water were the first to bounce back. This was not surprising perhaps because shallow water receives more light energy, and corals need light to grow. The deeper corals’ recovery lagged by a few years but have been recovering too, and I think that, from preliminary analyses of our results, the deeper corals have now seriously begun to catch up.

In lagoons, coral survival was all much better, perhaps because lagoon water is used to episodic raised temperatures in the way that ocean facing corals were not. All this raises a rather alarming thought: even in an area with no other external stresses like fishing or sewage, not to mention stresses from construction and so on, coral reefs take more than a decade to recover at the best of times and in the best of circumstances.

This is a cautionary tale for anybody concerned with coral reef resources management.

Helen – One of the new studies your team has untaken is investigating the reef fishes’ fear responses (or lack of). Is it obvious that the fish are less scared of people in Chagos compared to other places you’ve dived? (I have in mind the Galapagos fauna that are said to be relatively fearless of human presence).

Charles – Fish results are being worked up right now but broadly, yes, fish will approach you, or let you get closer to them, to a very much greater extent than anywhere where there is fishing. For those of us who have worked, as most of us have, in areas where there is fishing, the difference is striking.

We have photographs of divers trying to examine their quadrats at arms length from them, with the space between them are and surface full of fish!  A very nice experience indeed, and this happens sometimes when schools swim by and simply don’t try and avoid you.  But it is an unexpected complication to trying to do the work!

We’ll hear more from Charles later in the week. Until then, read the Chagos expedition blog here

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