The survival of sea birds affected by ocean cycles

Date:  May 17, 2018

Source:  CNRS

Several ocean cycles, such as the El Niño phenomenon, occur in the Pacific ocean and have climatic repercussions around the globe (e.g. intense rains in South America, mild winters in Canada, etc.) However El Niño (with a periodic oscillation of 2 to 7 years) is not the only natural and cyclical variation observed in the Pacific: the Pacific decadal oscillation (PDO) is a variation in surface water temperatures which causes significant changes in sardine and anchovy population sizes due to upwelling, a process in which nutrient-rich deep ocean water rises to the surface.

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If El Ninos happen twice as often in the future, what happens to seabirds?

May 7, 2018, UC Davis

More frequent El Niño events in the future may have surprising impacts on seabirds and some fish species, according to a study from the University of California, Davis.

El Niños are unusually warm ocean conditions that occur every two to seven years off the Pacific Coast, bringing with them poor ocean productivity and sometimes catastrophic weather conditions. Fossil coral records and climate change models indicate that El Niños occurred both more and less frequently over the past 1,000 years than they do now, and climate change may speed up or slow down their frequency in the future.  

In a modeling study recently published in the journal Theoretical Ecology, UC Davis researchers in the Department of Wildlife, Fish and Conservation Biology wondered how changes in frequency of El Niño and its more favorable, cool-water counterpart La Niña might affect Brandt's cormorant. The seabird was selected as a model species because of its known sensitivity to environmental changes. 

"We expected that if you increased the frequency of El Niños it would have a negative impact on the population," said lead author Annie Schmidt, a Ph.D. student at UC Davis during the time of the study and currently a researcher at the nonprofit Point Blue Conservation Science. "It turns out it was exactly the opposite."

Taking the good with the bad

The study's models indicated that doubling the frequency of the El Niño-Southern Oscillation (ENSO) phenomenon, which includes El Niño and La Niña, unexpectedly resulted in higher population numbers and a lower chance of extinction for Brandt's cormorants. 

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Drastic Drop in Baby Brown Pelicans: Blame El Niño?

By Becky Oskin, Senior Writer | June 04, 2014 03:12pm ET

An endangered species success story is suffering this year, perhaps because of El Niño.

California brown pelicans almost completely failed to breed at their nesting sites in Mexico this year, surveys have found. Scientists are reluctant to blame any one cause for the drastic decline in fuzzy-headed baby pelicans, but a similar drop in breeding numbers struck during previous El Niño events. 

"Over the years, we've seen that during an El Niño, their breeding effort goes way down," said Daniel Anderson, a University of California, Davis wildlife biologist who has monitored California brown pelicans for 46 years. Overfishing of sardines and habitat loss could also be hurting the pelican population, Anderson said.

Continued