Eilat_ColdStress_Corals
Complete Raw Physiology Data file: "complete_rawdata_coldstress_Bellworthy.xlsx"
Raw data for use with R markdown files: "acropora_rawdata_clean.csv" and "stylo_rawdata_clean.csv" R code template for data visualisation, parametric assumption testing, and statistical tests: "Coldstress_DataVis&StatsClean_Bellworthy.Rmd" R code for creation of graphics: "graphics_coldstess_acro.Rmd" and "graphics_coldstress_stylo.Rmd"
Article title: Warming resistant corals from the Gulf of Aqaba live close to their cold-water bleaching threshold
Jessica Bellworthy1, 2*, Maoz Fine1, 2
- The Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, 5290002, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, P.O.B. 469, Eilat, 88103, Israel
*Corresponding author: jhbellworthy@gmail.com; +972 (0)586637259
Running title: Cold water coral bleaching in the Gulf of Aqaba
Keywords: Acropora eurystoma, coral physiology, photosynthesis, Red Sea, Stylophora pistillata, symbiont
Abstract Global climate change is causing increasing variability and extremes in weather worldwide, a trend set to continue. In recent decades both anomalously warm and cold seawater temperatures have resulted in mass coral bleaching events. Whilst corals' response to elevated temperature has justifiably attracted substantial research interest, coral physiology under cold water stress is relatively unfamiliar. The response to below winter ambient water temperature was tested for two common reef building species from the Gulf of Aqaba in an ex situ experiment. Stylophora pistillata and Acropora eurystoma were exposed to 1 or 3°C below ambient and a suite of physiological parameters were assessed. At 3°C below ambient (ca. 18.6°C), both species had significant declines in photosynthetic indices (maximum quantum yield, electron transport rate, saturation irradiance, and photochemical efficiency) and chlorophyll concentration compared to corals at ambient winter temperatures. It was previously unknown that corals at this site live close to their cold-water bleaching threshold and may be vulnerable as climate variability increases in magnitude. In order to determine if the cold winter reduces the known heat resistance of this population, the corals were subsequently exposed to an acute heat shock of 3°C above typical summer temperatures. Exposed to above ambient temperatures, both species showed fewer physiological deviations compared to the cold-water stress. The cold winter experience did not increase corals' susceptibility to warming. This study provides further support for the selection of heat tolerant genotypes colonising the Red Sea basin and thereby also supporting the mechanism behind the Reef Refuge Hypothesis.