Spatial and temporal photoacclimation of Stylophora pistillata: zooxanthella size, pigmentation, location and clade

摘要: Photoacclimation of the symbiotic hermatypic coral Stylophora pistillata was studied both for colonies growing at different depths (1 to 20 m) sampled within same season ('spatial photoacclimation') and depth (5 but throughout year ('temporal photoacclimation'). Specimens were darker had increased chlorophyll densities (chlorophyll per surface area) under low-light conditions caused by and, in shallow-growing specimens, winter season. However, while involved zooxanthella content, acclimation low irradiances corals during mostly an increase algal density. In corals, zoox- anthella content density fluctuated seasonally correlation with light more than nitrogen or temperature. This could be related fact that reefs Eilat, Israel, are exposed solar radiation many other world. Histological analyses high-light showed zooxanthellae located deeper inside host tissue smaller diameter compared from corals. Additionally, deep-water hosted clade C zooxanthellae, shallow waters, high- very environments, A. These differences found affect physiol- ogy, as examined a short-term thermal stress experiment, clade-A having higher resilience clade-C colonies. Taken together, our results show evidence mechanisms help adjust light-capturing abilities S. spatial temporal changes irradiance.