THE BIOLOGICAL COMMUNITIES OF AN EXTREME ENVIRONMENT: THE BLUE HOLE OF FAANU MUDUGAU, MALDIVES

LE COMUNITÀ BIOLOGICHE DI UN AMBIENTE ESTREMO: IL BLUE HOLE DI FAANU MUDUGAU, MALDIVE

Abstract

The Faanu Mudugau Blue Hole (Maldives) opens at 30 m depth and descends to 85 m. At 40-50 m the water' temperature, salinity and pH change significantly. Below 50 m oxygen concentration collapses, while hydrogen sulphide increases. This work provides a first characterisation of the maldivian blue hole benthic communities. Data were collected from 30 m to 75 m by taking photographs every 5 m depth. Each photoquadrat was analysed to calculate the percent cover of any organism, on which a Corrispondence Analysis (CA) was applied. Three zones was identified: i) a photic zone at 30-40 m depth, dominated by encrusting algae, sponges and scleractinians; ii) a mesophotic zone at 45 m, dominated by Chrysophyceae and Cyanobacteria; and iii) an aphotic zone below 50 m, where only chemosynthetic bacteria are present. Further investigations on the Faanu Mudugau Blue Hole are worthy to better understand the functioning of this extreme ecosystem.