A team of researchers from Tokyo Metropolitan University has conducted an in-depth analysis of the evolution of drift pumice following the 2021 Fukutoku-Oka-no-Ba underwater volcanic eruption in Japan. The study, based on samples from 213 locations across Japan, Thailand, and the Philippines, provides critical insights into how pumice rafts change over time, including their fragmentation, organism attachment, and transport mechanisms.
The findings, published in a recent study, offer a first-of-its-kind time-lapse perspective on the three-phase transformation of pumice rafts. Understanding these changes is vital for disaster mitigation efforts, as pumice rafts can disrupt fisheries, damage ports, and impact marine ecosystems.
Three Phases of Pumice Raft Evolution
Researchers, led by Assistant Professor Daisuke Ishimura, documented the pumice evolution over a year-long study, focusing on changes in size, roundness, density, and biodiversity of attached organisms. The study identified three distinct stages in the drift pumice’s transformation:
- Initial Phase (First 60 Days)
- Pumice rafts were densely packed, causing frequent collisions that rounded the sharp edges of individual pumice stones.
- High collision rates made organism attachment difficult, with only goose barnacles observed in this phase.
- Fragmentation Phase (60–210 Days)
- Continued fragmentation led to smaller pumice pieces, reducing raft density.
- Despite fragmentation, pumice maintained its roundness due to continued abrasion.
- Bryozoans (aquatic invertebrates) began to appear, but biodiversity remained low.
- Mature Phase (After 210 Days)
- Raft density decreased significantly, reducing pumice collisions and allowing more organisms to attach.
- Bivalves and coral species started colonizing the pumice, leading to a rapid increase in biodiversity.
- At this stage, pumice rafts dispersed completely, with pumice either sinking or washing ashore.
Implications for Disaster Preparedness and Marine Ecology
The research provides valuable insights into the long-term impact of pumice rafts on coastal environments and marine life. The ability of pumice to transport marine organisms across vast distances may influence species distribution, with potential ecological consequences.
From a disaster management perspective, monitoring the transformation of pumice rafts can help governments predict disruptions to maritime industries and develop mitigation strategies to protect ports, fisheries, and marine ecosystems.
The study was supported by JSPS KAKENHI and the Japan Science Society’s Sasakawa Scientific Research Grant, reinforcing Japan’s commitment to understanding and mitigating volcanic disasters.
As underwater eruptions continue to pose risks, this landmark research serves as a vital tool for future studies on pumice dispersal and its ecological impacts.
Add comment