Lithopyllum spp. as proxy of climate variability in the nw indian ocean

A previously unexplored subfamily of coralline algae, the Lithophylloideae, was investigated as potential paleoclimatic archive. For the first time, seasonal changes in Mg/Ca, Li/Ca and Ba/Ca composition of Lithophyllum spp. from the Gulf of Aden (Balhaf, Yemen), the Arabian Sea (Socotra, Yemen), and the South of Red Sea (Kamaran, Yemen) were investigated by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). For the first time in coralline algae, the Li/Ca composition was analyzed and showed a highly significant and positive correlation with Mg/Ca and SST. Monthly algal Mg/Ca and Li/Ca variations indicate a positive correlation with sea water temperature (SST). Although no correlation between monthly algal Ba/Ca and local (SST) was found, fluctuations in Ba/Ca indicate the influence of nutrients introduced by seasonal upwelling, and record an increase of sediment at the sampling sites. From the age model of Mg/Ca the annual algal extension rates were measured in all specimens of Lithophyllum spp., and they resulted highly variable, mainly influenced by light and occasional burial. The elementary ratio of Mg/Ca, Li/Ca and Ba/Ca, and annual extension rate were successfully used in historical reconstruction of the climate and oceanographic variability of the study area.