A rare opportunity to sample the Pacific Ocean immediately after a powerful hurricane has uncovered how storms can reshape marine ecosystems – in both positive and negative ways.
In 2018, a team of marine scientists embarked on a research voyage from Mazatlán in Mexico to San Diego in the United States to study oxygen minimum zones (OMZs) – naturally occurring, oxygen-poor areas in the ocean that are increasingly expanding due to warming seas.
But their plans were suddenly interrupted by the arrival of Hurricane Bud, a Category 4 storm.
Thanks to detailed weather forecasts and careful planning, the researchers safely navigated the storm by sheltering behind islands and adjusting their route. Once the hurricane passed, they were able to collect samples directly from the storm’s path – an extremely rare scientific opportunity.
“When we got there, you could actually see and smell the difference in the ocean,” says Michael Beman, a marine biologist and microbial ecologist.
“It was green from all the chlorophyll being produced. There were totally different organisms there, and they were going nuts in the wake of the storm.”
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How hurricanes impact ocean life
According Beman and his team, the storm had churned the water column so deeply that cold, nutrient-rich water from the deep ocean was drawn to the surface, triggering an explosion of phytoplankton. These microscopic algae form the base of the marine food web and are a vital food source for bacteria, zooplankton, small fish, shellfish and baleen whales. The bloom was so intense that it was visible from space.
However, the mixing also stirred up oxygen-poor waters from the depths, pushing them closer to the surface than usual – posing a threat to marine life that depends on higher oxygen levels.
The bloom was so intense that it was visible from space.
Samples collected by the team showed dramatic changes in oxygen levels and revealed how the hurricane had rapidly 'shoaled' the OMZ, moving it to shallower depths. The team also analysed DNA in the samples to identify the organisms reacting to the bloom. Unusually, they spotted many turtles far offshore.
“These hurricane-generated blooms are like oases for ocean organisms,” says Beman. “We detected a bacteria bloom, but I wouldn’t be surprised if larger organisms made use of the hurricanes.”
The findings, recently published in Science Advances, offer a rare look at how extreme weather can shape ocean life. Beman hopes future collaborations will explore even more about these dynamic ocean events.
Main image: ocean storm (note: not the storm documented in the study)
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