Sea change on the Pacific Ocean

El Niño, that extreme weather system known to wreak havoc on temperature, productivity and fisheries in the Pacific Ocean, as well as rainfall patterns around the world, has changed into something new.

Nicknamed the Modoki — a Japanese word meaning the same, but different — scientists have watched this new kind of El Niño develop since the 1990s.

But while several papers have explained the Modoki’s physical effects on the tropical Pacific ocean, no one had examined how it affected ocean biology – until Dalhousie oceanography researcher Daniela Turk published a study in the journal Geophysical Research Letters.

Looking at El Niño’s biological effect

“While there has been significant research into the physical changes associated with El Niño Modokis, there have been no studies prior to ours to determine whether they also induce a distinct biological response," she says.

In her 2011 paper, Dr. Turk and her co-authors used satellite data to compare decreases in biological productivity in the equatorial Pacific Ocean between El Niño Modokis (also called Central Pacific or CP-El Niño) and classical Eastern Pacific (EP) Niños

This month, Dr. Turk continues her research, as a co-author on a follow-up paper by Michelle Gierach from the California Institute of Technology’s Jet Propulsion Laboratory. Published in Geophysical Research Letters, their paper received a Research Spotlight in the American Geophysical Union’s weekly electronic supplement.

“The interaction was very inspiring,” she says of her collaboration with Dr. Gierach. “The fact that I met a younger female colleague who continued on this research and I could help with my perspective as well learn from her was very rewarding for me.”

El Niño and the food chain

In her first paper, Dr. Turk tied the CP El Niño to stronger declines in central Pacific phytoplankton and biological productivity, but found it had a less drastic effect on the eastern Pacific compared with EP El Niños.  Her most recent paper further explored the responsible physical mechanisms behind these changes in biology.

Both studies suggests that a predicted future shift to more frequent CP El Niños could alter ecosystem dynamics in the equatorial Pacific Ocean. It would enhance phytoplankton and biological productivity in the eastern basin and decrease in the central area.

“This changes in the basic building block of the ocean’s food chain could have an effect on distribution and abundance of zooplankton and fish.”

This might prove a possible benefit for the eastern region’s fisheries, and Dr. Turk is interested in connecting with biologists in the Dalhousie-managed Ocean Tracking Network to look at the effect of changing El Niño patterns on Pacific Ocean fisheries.

“I would like to find someone with data from the fisheries side, while I could provide oceangraphic perspective.”

Her work is an important step in understanding the effects of this new weather event on many ecological levels around the world.

“Because some scientists expect it to become the dominant El Niño variant in response to global warming, understanding their differing effects is a pressing concern to us all,” she says.