Development of short core sampling machine from live coral

Massive corals form annual rings in their skeleton. By analyzing the annual growth changes and composition of elements, history of coral health and environmental conditions can be examined. The authors planned to use massive coral as an indicator of local undersea events such as the effect of land flow. For this purpose, a core-sampling machine was developed to collect many short cores from a wide area. It consists of a guide frame and two pneumatic drills. The frame is fixed on the coral by an anchoring drill which drives three anchor drills. Then a boring drill is operated by the support of the guide frame. Power for the drill is supplied from the second stage of a SCUBA regulator. The size of the core is 25 mm in diameter and 200 mm in length. The hole in the coral is filled by coral sand, and the surface is hardened by underwater cement to help the surface of the hole to recover. Eighty cores of two massive coral species, Porites lutea and Porites lobata, at twelve survey sites in Sekisei Lagoon (25×20 km), Okinawa, were sampled by using the machine in boreal autumn 2000. Biomass and number of zooxanthellae were measured from the core surface. Development of the core-sampling machine and the actual core sampling procedure are presented