Mesophotic and deeper habitats (∼40 to 350 m in depth) around Rapa Nui (Easter Island) were investigated using a remotely operated vehicle. We observed extensive fields of filamentous cyanobacteria-like mats covering sandy substrates and mostly dead mesophotic Leptoseris spp. reefs. These mats covered up to 100% of the seafloor off Hanga Roa, the main village on the island, located on its western side. The highest mortality of corals was observed at depths between 70 and 95 m in this area. Healthy Leptoseris reefs were documented off the northern and southeastern sides of the island, which are also the least populated. A preliminary morphologic analysis of samples of the mats indicated that the assemblage is composed of at least four filamentous taxa, including two cyanobacteria (cf. Lyngbya sp. and Pseudoanabaena sp.), a brown alga (Ectocarpus sp.), and a green alga (Cladophora sp.). An ongoing eutrophication process is suggested as a potential driver of the proliferation of these filamentous mats off Hanga Roa village.

Depth range
40- 350 m

Mesophotic “mentions”
27 x (total of 4324 words)

Classification
* Presents original data
* Focused on 'mesophotic' depth range
* Focused on 'mesophotic coral ecosystem'

Fields
Disturbances

Focusgroups
Algae (Macro, Turf and Crustose Coralline)

Locations
Chile - Easter Island

Platforms
Remotely Operated Vehicle (ROV)