About_us
D-ARK (Deep-sea Archaic Refugia in Karst) is a research project that conducts deep-sea surveys to study biodiversity, targeting deep-sea limestone caves around mainly Daito islands.
Limestone caves are a treasure trove of relict species
Limestone caves form a unique environment isolated from the outside world, and many relict species called "living fossils" have been reported from limestone caves on land, freshwater, and shallow ocean ecosystems.
In the deep sea, for example, coelacanths fishes are known to live in caves on underwater cliffs. Deep-sea limestone caves are likely valuable habitat for other relict species. However, tools to investigate deep-sea caves have not been developed, and no research has been conducted on these ecosystems to date.
Survey of the sea area around mainly Daito islands
Minami Daito Island was formed near the equator 50 million years ago and continues to move northward. The island exists at its current position without ever being connected to any other land mass. As the island moves northward, the Philippine Sea Plate is subducting, and reef-building corals grow on top. As a result of thousands of years of reefbuilding coral growth, the upper 2000 meters of the island consists of limestone layers. When these limestone layers are eroded, splendid limestone caves are formed on land. No research has ever been conducted in the deep sea (beneath 200 meters depth) around Daito islands.
Minami Daito Island
“Hoshino Cave” Minami Daito Island's largest limestone cave
In order to clarify the existence of deep-sea caves and the organisms within them, we will conduct a full-scale deep-sea ecosystem survey at Daito islands. We will record images using remotely operated vehicles (ROVs) and baited cameras. We will develop an endoscope and a mini ROV that will be used to better study undersea caves. In addition to video data, we will analyze environmental DNA using a CTD rosette and eDNA sampling device “MASS pump”. Finally, we will also collect invaluable biological samples using ROVs and fishing surveys to describe new deep-sea, cave-dwelling species.
Project structure
The D-ARK Project is lead by Japan Agency for Marine-Earth Science and Technology(JAMSTEC), University of the Ryukyus, IDEA Consultants, Inc, FullDepth Co, Ltd, and Enoshima Aquarium.
This research is supported by the Ocean Shot Research Grant of the Sasakawa Peace Foundation.
Links：Limelight on limestone caves: refugia for relict fauna?
