Description from NSF award abstract:
The strongest coral bleaching event in nearly 20 years began in American Samoa in January 2015. Coral bleaching occurs when ocean water temperatures exceed a coral's normal heat tolerance. But bleaching events usually show an unexplained pattern - colonies next to one another can show very different levels of bleaching - from pure white to the normal tan color of a healthy coral. The investigators have observed this pattern among 280 corals on reefs in American Samoa that have been studied for years. This system will be used to test four major hypotheses about what causes some corals to bleach and some not: differences in 1) species, 2) the temperature the corals experienced, 3) the symbiont they harbor, and 4) the genotype of the coral host. In addition, the investigators will return to American Samoa at regular intervals to measure the rate of recovery of each coral colony and conduct the same tests as above for recovery rate. The stark-white reefscapes left behind by bleaching events are one of the most common signals of increased ocean warming. This work will take advantage of years of prior study and the advent of a coral bleaching event to understand the rules for survival on reefs.
The reefs of American Samoa began showing a major bleaching event starting in January 2015, including 62 corals that have been intensively studied for coral thermal resistance, field temperatures, and symbiont type. In April 2015 the investigators monitored bleaching status of these and additional corals, totaling 280 corals from four species, and uncovered marked variation in bleaching extent within and between species and within and between reef regions. The team will test the relative importance of microclimate to bleaching state by examining records of approximately 50 temperature loggers in place since before the bleaching event. They will test the influence of symbiont type and host gene expression profiles by examining samples of 60 colonies taken at four time points after bleaching. The investigators will also examine the full suite of 280 corals for genetic variation to estimate the relationship between bleaching state, recovery rate and genetic polymorphism. These data will be used to test micro-climate, symbiont, and coral genetics as determinants of bleaching and bleaching recovery. Because the investigators have samples from these 280 colonies before bleaching mortality, this study will provide the first estimate for the evolutionary impact of a bleaching event on coral populations.
Dataset | Latest Version Date | Current State |
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Coral colony photographs taken at four time points between April of 2015 and April of 2016 during and after a bleaching event on Ofu Island, American Samoa. | 2019-03-27 | Preliminary and in progress |
Coral colony genetic sequence accession numbers for samples collected from the lagoon environment of Ofu Island, American Samoa between 2011 and 2015. | 2019-03-18 | Final no updates expected |
RNA sequence accession numbers for coral colonies that displayed a strong bleaching phenotype at Ofu Island, American Samoa between 2015 and 2016. | 2019-03-18 | Final no updates expected |
Water temperature at coral colony locations in American Samoa between 2013 and 2016 (Mass Bleaching American Samoa project) | 2017-01-24 | Final no updates expected |
Principal Investigator: Stephen R. Palumbi
Stanford University - Hopkins (Stanford-HMS)
Contact: Stephen R. Palumbi
Stanford University - Hopkins (Stanford-HMS)
Data Management Plan received by BCO-DMO on 10 June 2016. (78.99 KB)
06/10/2016