Negative impacts of pumice drifting on reef-building corals

A submarine volcano erupted near “Fukutoku-Oka-no-Ba” in the Ogasawara region of Japan in August 2021. In November 2021, substantial pumice deposition was observed in the coral reef areas around Okinawa Island. Re-suspended pumice afloat from May to June 2022, coinciding with coral spawning, was observed. The effects of pumice on corals are largely unexplored, prompting this study to assess the potential effects of pumice on the various life histories of corals through field surveys and laboratory experiments. Pumice deposition, particle composition, and direct injuries to the surface of corals were examined in the field between November 2021 and May 2022. The effects of varying amounts of pumice were tested on the embryos and larvae of Acropora digitifera, a dominant shallow-water corymbose coral species. Our results, based on larval morphology and survival, indicate that high levels of pumice can lead to an increased abnormal development of embryos with higher mortality rates. This study provides the first evidence of the direct impact of pumice on the early life stages of A. digitifera and offers crucial insights into the potential consequences of pumice on coral reef ecosystems.