A study led by researchers at the University of Arizona shows the vast amounts of volcanic ashes released into the atmosphere ended up in the ocean, particularly in the Southern Ocean, where they provided a smorgasbord for marine algae to feast on.
Volcanic ash is known to contain important nutrients, including phosphorus, iron and silicon. A significant increase in volcanic activity in the Andes, peaking between eight and four million years ago, likely delivered a significant pulse of nutrients, especially iron, to the Southern Ocean.
University of Arizona Associate Professor of Geosciences Dr. Kaustubh Thirumalai and Dr. Barbara Carrapa, Professor of Geosciences, joined “Arizona Horizon” to discuss the ways this development induced a chain reaction driving environmental change.
According to Dr. Carrapa, the ashes were from volcanic eruptions about 8 million years ago in the Miocene period. The central Andes Mountains were very volcanically active at this time and are considered to be the strongest volcanoes we know about on earth.
“They basically erupted a large amount of ash, which eventually was moved by wind and rivers, into the oceans,” Dr. Carrapa said. “It made it all the way to the Southern Ocean, which is a key place for climate and marine productivity and carbon storage.” She added this caused the entire marine ecosystem to change, including an impact to some of the biggest mammals we have in the ocean. It impacted the carbon cycle by increasing the storage into the ocean, which impacts global cooling.
Dr. Thirumalai said the ash directly affected the lives of whales in the ocean. This was discovered through fossils of blue whales, which are considered to be the largest animals in earth’s history.
“Weirdly enough, their evolution and when they come into the record seems to coincide after this volcanic event in the Andes that we have uncovered,” Dr. Thirumalai said. He explained as the ash covered the ocean, it made way for tons of nutrients and plankton, but not all of the effects were good for the whales.
“The algae was actually harmful to the whales, and so we think that this eventually led to these massive death beds and accumulation that we found in Southern Chile,” Dr. Thirumalai said.
Though the direct effects of the volcano in the area are usually bad, including bad air quality and global warming, the effects at a distance and over the years are very good for marine life. In the case of the Andes, the ash spread in the water down to Antarctica and created thriving nutrients and life.
