Meeting Abstract
In July 2016, the pristine East Bank of the Texas Flower Garden Banks National Marine Sanctuary experienced unprecedented mass mortality of multiple invertebrate species, which caused highly localized reductions in coral cover. As part of a scientific team tasked with identifying the cause of the devastation, we collected gene expression samples from affected and unaffected coral colonies to determine the physiological consequences of the event on tissues from two congeneric coral species (Orbicella franksi and Orbicella faveolata) from both the East (affected) and West (unaffected) Banks. At the affected site, we preserved three types of tissue samples: apparently healthy colonies (no symptoms), affected colonies along the lesion of tissue loss progression, and healthy tissues from affected colonies (i.e., at least 30 cm away from lesion). Genome-wide gene expression libraries (N = 76) were prepared in-house and sequenced on the Illumina HiSeq 2500 platform. Both coral species exhibit similar gene expression patterns across tissue types. Apparently healthy tissues from affected colonies show no significant differences in overall gene expression compared to tissues from completely healthy colonies, but many genes are differentially expressed in the affected tissues relative to both healthy tissue types. Gene enrichment analysis suggests that affected coral tissues were experiencing oxidative stress and up-regulating genes related to mitochondrial processes, suggesting that hypoxia may have played a role in the mass mortality event on the reef. These data also highlight the diagnostic power of an affordable next-generation sequencing methodology using ecological samples.
