Wonders of Ogasawara Islands

Author: Andrew Baird

The Ogasawara Archipelago is a group of approximately 30 islands in the northern Pacific. The islands are part of the territory of Japan. The Ogasawara Islands are an important location in terms of taxonomy because they are the type location for nine nominal species. The islands were visited by the US Northern Pacific Exploring Expedition in 1856. Specimens collected on that expedition serve as the type material for three nominal species described by Verrill (1866). In the 1930s, Yabe and colleagues described a further six nominal species from the Islands. Only two of these nine species are currently accepted, and one Boninastrea boninensis Yabe & Sugiyama, 1935 has been declared extinct by the Japanese Ministry of the Environment.  

To visit the Islands, I joined a team led by Dr James Reimer from the University of the Ryukyus and colleagues from the Okinawa Institute of Marine Science. The World Heritage listed islands have a certain mystique. The only way to get there is a 24 hours long ferry ride from Tokyo. The colour of the water is known as Bonin Blue – a deep reflective blue that you only see in the open ocean. The visibility on our dives was regularly over 40 m.

Figure 1. The famous “Bonin Blue” around Ogasawara Islands.
Photo credit: James Reimer

The terrestrial landscape is a little stark, with the soil too thin to support much in the way of forests, but the cliffs and coastline are spectacular. The corals were little thin on the ground in the spots we managed to dive, generally around 10-20% cover, and growing on rocks rather than aggregated reef. However, the corals were reasonably diverse: I managed to image approximately 140 different species over the course of 7 dives. The sites we dived were also notable for the lack of Acropora, indeed, I only imaged about 8-10 species, some of which I have never seen before.

Figure 2The terrestrial landscape (that includes a heart rock!) that stimulates imagination to what prehistoric times might have looked like.
Photo credit: Andrew Baird

Unfortunately, our search for topotypes (Fig. 3) was cut short when one of the team caught covid and those of us that were still healthy were bundled on to the return ferry to Tokyo after negative RAT tests. We will be back again next year to the resume the hunt for B. boninensis and the other topotypes we missed in the magical Ogasawara Islands!

Figure 3. Potential topotype for Psammocora vaughani Yabe & Sugiyama 1936; (a) field image of 59-7039; (b) skeleton of 59-7039; (c) holotype of P. vaughani Yabe & Sugiyama 1936 IGPS 44975.
Photo credit: Andrew Baird

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