Conserving Chagos: More rough seas and Crowns of Thorns

The strong winds are starting to take a toll on the divers. So far it hasn?t stopped any work yet but heavy sea conditions have made what is normally a fairly effortless task into hard work, and one data logger located in a storm corner of reef was left because the sea was too rough for safety. Yesterday morning a short squall with over 40 knot winds made for an extremely uncomfortable period for the surface team who huddled in the wind and rain.

When the divers surfaced at the end of the squall, all smiles and comments about how rich the coral was, they were surprised to see some miserable faces greet them. In the afternoon, a trip to the seaward side of Eagle Island had to be abandoned before we got there due to very high waves making it potentially dangerous. However, a reserve site in the lagoon proved to be very rich in the species that some of us were sampling.

In Eagle Island, we also found an area which is undergoing an outbreak of Crown of Thorns starfish (COTs). There is a large area of dead Acropora coral, which are COTs favourite food. That which was dead for some weeks is covered in algae, while that which is recently dead is bleached pure white, and among these newly dead bleached patches we found aggregations of about 20 COTs per square metre. We took the opportunity to map the area affected and found that it fortunately goes only half way down Eagle Island rather than covering its entire coast.

Sailfish Eagle - photo: Anne & Charles Sheppard/ Chagos Conservation Trust

Expedition doctor Bob Long made a manta board and was towed along the length of Eagle Island; as a result the heavily impacted area has been mapped along with the approach front of the outbreak and the as yet unimpacted area. We have taken several GPS coordinates to plot the boundaries of the area so we can look to check on extent of damage and recovery sometime in the future. Usually these outbreaks are completely natural, and being a healthy reef system, we predict that the corals here will bounce back in a short time, given that there are no other stressors acting on the reefs here.

One dive team caused a lot of envy amongst the rest of us by seeing a sailfish swim by. It was about 2 metres long and swam past only about 10 metres away from the divers. We will post the picture of it when we return to Diego Garcia.

In the evenings we are continuing the Pacific Marlin Seminar Series (rated by some to be on a par with far grander lecture series!) which started with the expedition in 2006. After the evening briefing, each scientist gives a short presentation on their research. As we are a collection of scientists from all over the world and working on a variety of topics, we have a lot to learn from each other. This exchange of information is very important and already several cross disciplinary research ideas have been discussed.

Previously in this series:

Conserving Chagos: Science Expedition to World?s Largest ?Ocean Park?
Conserving Chagos: Starting Out
Conserving Chagos: Manta Rays
Conserving Chagos: Last Day around Diego Garcia
Conserving Chagos: Salomons Atoll
Conserving Chagos: Stormy weather
Conserving Chagos: Nelsons Island
Conserving Chagos: Peros Banhos atoll
Conserving Chagos: Thoughts from the Diving Officer
Conserving Chagos: Last Day at Peros Banhos atoll
Conserving Chagos: On our way to Three Brothers
Conserving Chagos: More on the Three Brothers

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