The ecosystem responded much as the researchers would have expected to the high temperatures and changes in acidity caused by the uneasy volcano south of El Hierro island. But the strength of the response was a surprise, study researcher Eugenio Fraile-Nuez of the Instituto Español de Oceanografía in Spain told LiveScience.
"The physical and chemical response of the system was predictable, but we never have imagined that we would reach this magnitude," Fraile-Nuez said. [Images: Wild Volcanoes]
Over the crater, the water heated up by as much as 65 degrees Fahrenheit (18.8 degrees Celsius), the researchers found. Dissolved oxygen in the water all but disappeared, decreasing by 90 percent to 100 percent in places. Meanwhile, carbon and carbon dioxide values shot up, and the pH of the water went down by 2.8, meaning it became more acidic.