Coccolithophore Assemblages from Gulf of Aqaba Sediments and their Response to Climate Change

The Gulf of Aqaba exhibits a nearly closed marine ecosystem, characterized by oligotrophic conditions, which give it the potential for phytoplankton to flourish.Coccolithophore samples were taken from two different sediment cores that were collected from the northern Gulf of Aqaba during the OceanX expedition.This study aims to construct the sea surface temperature over the past few hundred years by counting fossil coccolithophore communities in the northern Gulf of Aqaba through time.The forty-eight smear slides were prepared for coccolithophore identification and paleo-ecological investigation, and then studied under a polarized microscope with 1500x magnification.Taxonomic identification of coccolithophores is based on the outer scale found in the slides.A total of 300 specimens were counted in each slide.To assess the temperature, diversity and the relationship between species abundances, statistical indices were applied on the counted specimens.Coccolithophore assemblages are extremely abundant in well-preserved conditions, allowing for clear identification and an exact assessment of climatic change based on paleo-ecological studies.The Gephyrocapsa group, Emiliana group, Helicosphaera spp, Reticulofenestra spp, Coccolithus spp, Pontosphaera spp, Braarudosphaera spp and Umbilicosphaera spp were found in high numbers throughout all the cores.The Emiliana Group was the most abundant genus throughout all the cores, indicating long-term warming.Throughout core 3, the results showed a strong relation between Gephyrocapsa spp and the other coccolithophores, such as Coccolithus spp, Helicosphaera spp, and Braarudosphaera spp, as all of these species prefer cold water.The fluctuations in the numbers of the cold-preference (Gephyrocapsa) group versus warm-preference coccolithophores (Emiliana Group) led to tracking periodic changes in climate.The significant increase in numbers of Gephyrocapsa oceanica, Gephyrocapsa muellerae, Gephyrocapsa ericsonii, and Calcidiscus leptoporus in some samples, relative to the Emiliana Group, reveals that a cold environmental period dominated the Gulf during the Holocene.