Meeting Abstract
37.2 Friday, Jan. 4 Host adaptation to thermal extremes? Evidence from the coral Porites lobata BARSHIS, Daniel/J*; STILLMAN, Jonathon/H; GATES, Ruth/D; TOONEN, Robert/J; SMITH, Lance/W; BIRKELAND, Charles; Univ. of Hawaii, Manoa; San Francisco State Univ.; Univ. of Hawaii, Manoa; Univ. of Hawaii, Manoa; Univ. of Hawaii, Manoa; Univ. of Hawaii, Manoa barshis@hawaii.edu
The Ofu Back Reef in the Nat. Park of American Samoa hosts a wide variety of corals that withstand mean temperatures (up to 30oC) and daily fluctuations (3-4oC) greater than most coral reef habitats. Despite these known stressors, back reef corals appear healthy and exhibit limited bleaching. We hypothesized that frequent exposure to the fluctuating environment of the Ofu Back Reef enhances the corals ability to cope with environmental stress. Samples from 4 source colonies of Porites lobata from the back reef and 4 from the neighboring forereef were cross and back transplanted to each location. Transplants were conducted in Jan 2005 and sampled every 24 hrs over 5 days (n=40). Heat shock protein 70 (Hsp70), ubiquitin-conjugated proteins, manganese superoxide dismutase (MnSOD), and 4-Hydroxynonenal (4-HNE) protein levels were analyzed by Western blot for each sample. Ubiquitinated protein levels were higher in back reef corals for all transplants and all days (p>0.001), indicating higher levels of protein damage or protein turnover. Hsp70, MnSOD, and 4-HNE levels were higher in back reef corals (p>0.01), although not consistently for all days and sites. There was no difference in levels of any protein measured between cross and back transplants for back reef or forereef corals, suggesting that the corals are acclimatized or adapted to their native environments. Analysis of mitochondrial DNA (coral host), and nuclear rDNA (host and symbiont) revealed significant population structure between back reef and forereef hosts but not symbionts, providing additional evidence indicating a host adaptive response to the different environments.
