CISME: A self-contained diver portable metabolism and energetics system

This paper describes a self-contained diver-portable instrument designed to non-destructively measure coral respiration and photosynthesis in situ. In situ instruments are needed to promote rapid assessment and monitoring of metabolic health of corals and other benthic organisms affected by ocean acidification, global warming, and other stressors, both anthropogenic and natural. Non-destructive tools are especially needed for reef corals because their live cover is greatly reduced and destructive sampling in many locations is prohibited. University of North Carolina Wilmington and Physical Sciences Inc., under the auspices of the NOAA-funded Cooperative Institute for Ocean Exploration, Research and Technology, have designed, fabricated and field tested such an instrument. CISME (Coral in Situ Metabolism and Energetics) is a compact instrument that measures dissolved oxygen, pH and temperature, which can then be used to determine respiration and photosynthesis rates of corals and a variety of other marine organisms. CISME has a sample port for introducing reagents (e.g. CO₂ enriched seawater) or withdrawing water samples for analyses that require laboratory instrumentation (e.g. total alkalinity for calcification rates). The instrument has a broad spectrum light array capable of mimicking natural light intensities during photosynthetic measurements. Laboratory and field tests demonstrate that the instrument produces quick, consistent metabolic measurements, as well as photosynthesis vs. irradiance response curves. These features make CISME suitable for experiments with pollutants and for ocean acidification research. The new technology will provide a new field tool for assessing coral reef ecosystem health.