Mesophotic coral ecosystems (MCEs) in Japan are currently only reported from the Ryukyu Islands and remain poorly known compared to shallow reefs in the region. MCEs in the Ryukyus were first examined in the 1960s and are among the earliest-studied MCEs globally. MCEs in the region support a high diversity of flora and fauna due to a combination of factors including the warm poleward-flowing Kuroshio Current, the complex geomorphology and diversity of habitats, and the proximity to the Coral Triangle. Recent research into the biology and ecology of mesophotic corals has examined questions such as ecological connectivity between mesophotic and shallow corals and revealed that several coral species span shallow to lower mesophotic depths (>60 m). Observations of reproduction in Seriatopora hystrix and Acropora tenella suggest that the propagule release period of both species is broadly synchronous in shallow and mesophotic corals, although the reproductive season is considerably shorter in mesophotic corals. MCEs in the Ryukyu Islands face stressors similar to shallow coral reefs such as climate change and rapid coastal development. However, the knowledge required to understand the response of MCEs to these threats is sparse. Despite evidence that at least some MCEs appear capable of recovering from disturbances (such as typhoons), investigations on how coastal development affects MCEs and how to mitigate threats to MCEs are urgently needed.

Depth range
30- 60 m

Mesophotic “mentions”
109 x (total of 6023 words)

Classification
* Focused on 'mesophotic' depth range
* Focused on 'mesophotic coral ecosystem'

Fields
Biodiversity
Climate Change
Community structure
Connectivity
Disturbances
Ecology
Geomorphology
Reproduction
Taxonomy

Focusgroups
Algae (Macro, Turf and Crustose Coralline)
Antipatharia (Black Corals)
Fishes
Octocorallia (Soft Corals)
Other invertebrates
Porifera (Sponges)
Scleractinia (Hard Corals)

Locations
Japan - Ryukyu Islands (Okinawa)

Platforms
Autonomous Underwater Vehicle (AUV)
Baited Remote Underwater Video (BRUV)
Drop / Towed Video
Manned Submersible
SCUBA (open-circuit or unspecified)