Bernard’s Knoll - The underwater meadow

In 2006 coral scientists started a decade long monitoring project to document the changes to this reef in the Chagos Archipelago of the British Indian Ocean Territory.
Bernard’s Knoll - The Underwater meadow
Bernard’s Knoll is an unusual reef in that it is a site inside the Perhos Banhos lagoon, and has a maximum depth with is restricted to the maximum depth of the lagoon, and is flat or very gently sloping rather than having a step drop-off to oceanic depths like many of the exposed seaward sites.
The deeper areas of the site support an unusual reef community, consisting of foliose corals such as Montipora species, combined with a variety of green macroalgae such as Halimeda species. This community, combined with the almost flat slope give these deeper areas of the site the feel of an “underwater meadow”.
The shallower areas where the knoll rises towards the sea surface have in the past been dominated by some of the largest and most impressive stands of table Acropora species in the entire Chagos Archipelago. These were particularly evident in 2006, where they were large and healthy colonies of greater than 2 meters in diameter. These large colonies were still present and were largely healthy in 2013, and 2014, however, coral diseases such as White Band Disease have been comparatively prevent at this site, and have been contributing to the high levels of mortality of the table Acropora at Bernard’s Knoll.
During 2015 diseased and dead table Acropora had increased from the previous year. However the most dramatic change was following the 2015 warming and bleaching event, which resulted in the mortality of many of the large table Acropora corals, and could clearly be seen in 2016.