Meeting Abstract

6.5  Sunday, Jan. 4  Microarray analysis of the effects of symbiont type and microhabitat on heat stress responses in the coral Acropora hyacinthus WATERSON, Tyler*; BARSHIS, Daniel; STILLMAN, Jonathon; San Francisco State Univ.; Univ. of Hawaii, Manoa; San Francisco State Univ. waterson@sfsu.edu

In the face of climate change and the worldwide decline of coral reefs coinciding with rising sea surface temperatures, it is important to understand how corals may be able to cope with extreme temperature environments. In the back reef lagoon of Ofu, American Samoa, corals thrive in a diverse range of temperature microclimates including extremely fluctuating pools (28-36 C), and moderately fluctuating pools (28-32 C). Previous studies found that colonies of the scleractinian coral Acropora hyacinthus from extreme pools host only clade D Symbiodinium, while conspecifics in a moderate pool host both clade C and D Symbiodinium. While clade D is generally considered to confer heat tolerance, the specific effects of symbiont clade on host physiology are poorly known. To study the relative effects of symbiont type and microhabitat on the heat stress response of this coral, we exposed nubbins from 17 different colonies representing both pools to a control (constant 28.5 C), and two heat-ramp treatments. All aquaria were held at 28.5 C for one hour, after which the two treatment tanks were heated at a constant rate for 4 hours to 32 C and 34 C, respectively. After two hours of exposure to the maximum temperatures, nubbins were sampled and frozen at -80 C for genotyping and microarray analysis. Genotyping by RFLP analysis of the 18S ribosomal subunit was used to confirm symbiont clade prior to microarray experiments so that corals hosting clades C and D could be compared. Microarray analyses of transcriptome profiles were performed using a 4,980 gene microarray developed for Acropora palmata by the Medina lab at UC Merced. Supported by USGS BRD GCC program