Environmental Assessment of marine areas in Yemen, coral biodiversity and monitoring - 2005-2009 - TotalEnergies Yemen LNG

In Aden, Bir Ali, Burum, Al Mukallah and Balhaf, sampling of hard coral species (essentially Scleractinia), was carried out during SCUBA diving from approx. 1 m depth (Ras Bedo) to the limit of coral distribution between 6 and 32 m depth depending upon the station and the area. Non-destructive sampling of species was performed in order to obtain a species list per site as previously done for the Aden, Balhaf, Bir Ali, Burum, Al Mukallah and Kamaran areas.

The observers recorded each species encountered during the dive on a slate and each species was photographed with an underwater digital camera in an Ikelite housing. Digital images were then analysed and species presence records cross-checked with the manual records. The lists obtained were used to produce a species per site matrix.

In case of taxa which could not be readily identified underwater a specimen was collected and a preliminary identification based on skeleton macro-morphology was carried out. Destructive sampling was performed with hammer and chisel. For a number of selected problematic taxa, living tissues (approximately 1 cm2 of colony surface) was fixed in pure ethanol for further molecular analyses.

In Bahalf, in 2005, investigations were devoted by scuba divers to assess fish and coral richness and biodiversity. The principle consisted in free exploration, establishing the most possible exhaustive list of coral and fish species encountered during a 1 hour dive in each site in the bathymetric range of coral presence (mainly between 9 and 2 m depth). Submarine photographs were taken during the scuba dives.

All these observations were positioned using GPS measurements. During the 2006-2009 coral monitoring, the observer moves from the deepest to the shallowest limit of coral distribution (between 10 and 5 m and up to 70 cm deep in Balhaf). SCUBA diving and snorkelling observations can be combined in an area of approximately 100 m2 using the permanent LIT (Line intersept transect) lines for reference in order to relocate the same area for observations over time.

In case of species which could not be readily identified during the dive, sampling of part of the colony was performed for further identifications. Each sampled fragment was catalogued and labeled, left overnight in household bleach, rinsed in fresh water and dried under the sun. Specimens were then analyzed under a Zeiss Stemi D4 stereomicroscope and skeletal microstructure investigated in order to identify them to the species level.