The eruption that occurred six years ago in the Los Lagos Region allowed us to analyze how the “fresh” ash contributes to the marine ecosystems of areas surrounding the volcano.
Daniela Jofré, Centro IDEAL. It was one of the largest volcanic eruptions of which there is photographic record in Chile. On April 22, 2015, the Calbuco volcano, located in Puerto Varas (Los Lagos Region), erupted after 54 years of inactivity, causing the temporary evacuation of more than six thousand people, cancellation of flights in the Southern Cone, and multiple damage in public works, among other effects.
The eruption caused lava flows and dispersion of volcanic ash, which spread through an immense eruptive column for several days, totaling at the end of the process three eruptive pulses in the span of a week, covering the solid surface the waters of the area with pyroclastic material; an opportunity that the marine biologist, Dr. Maximiliano Vergara -who was pursuing his doctorate at that time- did not miss.
“At that time, I was planning my thesis research. When the Calbuco volcano exploded, it happened that we had a long-term oceanographic monitoring station deployed in the Reloncaví Fjord, which allowed us to analyze the effect of the recently expelled ash on this ecosystem, the closest to the place of the eruption,” comments the marine biologist of the Center for Dynamic Research of High Latitude Marine Ecosystems (IDEAL) of the Austral University of Chile (UACh).
Dr. Vergara carried out several field campaigns, where he collected fresh ash samples, which were sent to Germany under strict conservation protocols. The work of the researcher at the Helmholtz Center for Ocean Research Kiel (GEOMAR), Dr. Mark Hopwood, determined how much was the amount of iron that this material released in contact with water. “Iron is a limiting component in both the Pacific Ocean and Antarctica. In the case of a volcanic eruption, the amount of material released into the atmosphere is large, they are very strong pulse dynamics,” explains Dr. Vergara.
The results showed that the iron contained in this type of ash was released almost automatically upon contact with seawater, which contributed to the abundance of this vitally important element in marine ecosystems. However, its level dropped rapidly as time passed. Dr. Vergara states that “most of the experiments in the scientific literature on the release of this component had always worked with ‘old’ ash that had been stored even for several years before the experiments, therefore, this work has great importance at a methodological level.”
The unique opportunity to study volcanic ash in its “fresh” state also allowed the evaluation of the flowering dynamics of coastal phytoplankton and the chemistry of carbonates during the period April-May 2015.
Together with Dr. Rodrigo Torres, researcher at the IDEAL Center and the Patagonia Ecosystem Research Center (CIEP), they were able to measure the contribution of ash to the calcium carbonate system in fresh water, related to acidification. “What we found is that the ash has an alkalinity effect on the water, which translates into higher phytoplankton production and primary productivity. These volcanic particles apparently had a fertilizing effect on the system,” says Dr. Vergara.
The researcher explains that algae blooms, generally occur in favorable climatic conditions (greater amount of light and temperature,) associated with the spring-summer seasons. However, the presence of volcanic material allowed the proliferation of these organisms at the bloom level even in an unfavorable context (mid-autumn, with little light and low temperatures.)
“Although volcanic eruptions release greenhouse gases, they also contribute to the formation of phytoplankton, which captures released CO2 and activates other biological processes, improves the chemical efficiency of water to permeabilize this component by adding alkalinity. Therefore, the ash did not contribute as a pollutant to the ecosystem,” comments the marine biologist.
The scientific research was published in the journal Ocean Science of the European Union of Geosciences and had the collaboration of the Institute of Aquaculture of the UACh, the Center for Oceanographic Research in the South-Eastern Pacific (COPAS) of the University of Concepción and the Department of Biology of the Dalhousie University (Canada).
Read the study here.