Recent progress in study on calcareous algae and algal sediments

The International Fossil Algae Association (IFAA), an international group of scientists who are interested in any aspect of fossil and living algae, organizes an international symposium every 4 years. Okinawa was selected to host the 11th International Symposium on Fossil Algae (Figure 1) because of great contributions to the study of calcareous algae by Japanese scientists such as Ryuji Endo, Wataru Ishijima, and Kenji Konishi (Iryu, 2004) and easy accessibility to modern and Pleistocene coral reefs for which many sedimentological and paleontological studies have been performed for more than 100 years (e.g. Iryu et al., 2006). The Symposium was held on September 14–18, 2015 with the support of the Geological Society of Japan and the Palaeontological Society of Japan. A total of 13 scientists from five countries attended the symposium. Pre-symposium field excursions (September 14–15) visited modern dasycladacean meadows (Figure 2) and Pleistocene carbonate deposits on Okinawa-jima, Central Ryukyus and coral reefs off Kerama Islands. The next 2 days (September 16–17) were devoted for the scientific sessions at the University of the Ryukyus. A special session was organized to discuss “Morphology versus molecular evidence in determining algal taxonomy and phylogeny.” A post-symposium excursion was conducted on September 18. We visited the Shuri Castle and then observed Pleistocene carbonate successions on southern Okinawa-jima. Although the number of participants was limited, there were prolonged discussions for every presentation. This thematic section collects recent studies on calcareous algae and algal sediments by IFAA members. Five papers are assembled here, covering Devonian to modern materials from Europe, Africa, and Japan.