The alga Caulerpa cupressoides in southern Diego Garcia.  This section of reef is different to all others so far seen in the archipelago.  It is dominated to at least 10 m by this seaweed, which is seen also on the reef flat here.  This stretch of reef faces into the SE tradewinds, and there is evidence to suggest that mild upwelling causes nutrient enrichment, favouring this plant at the expense of corals.  This photo shows a small patch, so that the underlying pink coralline algae can also be seen.  Coral cover on this reef is almost zero.
