One of the greatest threats climate change poses to coral reefs is bleaching, a response to heat stress in which coral expel the photosynthetic symbionts that provide them with key nutrients. Understanding how these "bleaching" events are triggered requires fine-grained measurements of coral colonies’ heat tolerance. A paper published recently in the journal Marine Biology) by CSUN Assistant Professor of Biology Nyssa Silbiger demonstrates an approach for this kind of measurement, which shows that colonies of a Caribbean coral species from warmer waters are more robust to temperature stress.
Silbiger and collaborators at the Bermuda Institute of Ocean Sciences, the University of North Carolina, and the University of Rhode Island measured thermal performance of Obribcella franksi, a reef building coral from the Caribbean, at its northern and southern range limits. They found that coral clones from the southern, warmer, range limit had lower sensitivity to warming, in terms of calcification, photosynthesis, and respiration. This differential thermal vulnerability suggests that key processes for coral ecosystem function may fail at different thermal thresholds in different parts of its range.
Image: A colony of Orbicella franski in Bermuda. (Nyssa Silbiger)