El Niño could trigger marine heat waves that threaten Pacific Ocean wildlife
Scientists warn that warming Pacific Ocean waters and marine heat waves fueled by El Niño could impact marine life, including sea lions, seabirds and sharks.
AccuWeather’s Jon Porter monitors the equatorial Pacific where El Niño conditions are leading to rising sea surface temperatures. This could lead to more tropical activity in the Pacific region.
Marine experts are sounding the alarm that El Niño’s impacts are expected to disrupt marine ecosystems and threaten species throughout the Pacific Ocean.
Experts from the Aquarium of the Pacific and the National Oceanic and Atmospheric Administration (NOAA) told reporters on June 11 that warming oceans and a developing El Niño could have significant consequences for marine life off the coast of Southern California.
El Niño can fuel marine heat waves
El Niño has developed in the Pacific Ocean faster and earlier than expected, according to AccuWeather meteorologists. This climate pattern happens every few years when sea-surface temperatures rise in the tropical Pacific near the equator and is expected to influence weather around the globe into 2027.
According to Dr. Andrew Leising of NOAA’s Southwest Fisheries Science Center, El Niño tends to trigger more marine heat waves. Prolonged periods of unusually warm ocean water can alter where marine species live, how long they survive and how successfully they reproduce.
“One of the most important things for the animals in the ecosystem is not necessarily just how hot it is ... but just how long they're exposed to the heat,” Leising said.
Stilt bird, April 6, 2013 (Image credit: Aquarium of the Pacific/Robin Riggs)
Marine heat waves can have devastating effects on marine life. Seabirds can starve from reduced prey availability, while sea lions can be exposed to harmful algal toxins, explained Brett Long, vice president of animal care, marine mammals and birds at the Aquarium of the Pacific.
Alaskan seabirds have also been experiencing die-offs linked to marine heat waves that have disrupted the food supply, per the U.S. Geological Survey (USGS).
Southern California waters are currently experiencing a heat wave expected to persist through August, experts warn. Combined with El Niño, the prolonged warmth could place additional stress on marine ecosystems.
California Sea Lion, March 31, 2022 (Image credit: Aquarium of the Pacific/Robin Riggs)
Warm waters could mean more shark sightings, disrupt ecosystems
Rising ocean temperatures also threaten resident ecosystems.
Nate Jaros, vice president of animal care, fish and invertebrates at the Aquarium of the Pacific, said warmer conditions attract nonnative species such as mahi mahi, yellowfin tuna and seahorses. Shark sightings may also increase off Southern California coasts.
Blue whales may also be forced to relocate as warming waters affect krill populations, their primary food source, Long said.
Heat waves are also taking a toll on kelp forests, which serve as vital feeding grounds, habitats and nurseries for marine life. Jaros noted that Northern California’s bull kelp forests have declined by about 90 percent since 2014.
“The effects of this decline trickle down to other species,” Jaros said.
Kelp, Northern Pacific Preview (Image credit: Aquarium of the Pacific/Andrew Reitsma)
Past effects from El Niño events
According to Dr. Ariel Cohen of NOAA’s National Weather Service, the impacts of El Niño vary from year to year, making it difficult to predict exactly how marine ecosystems will respond. With forecasters warning the emerging El Niño could be one of the strongest on record, it may result in significant impacts compared to others in recent years.
Past El Niño impacts include decreased plankton, which affects the food web, and the increased chance of harmful algal blooms, Dr. Leising noted.
As prey species move closer to the shore, marine mammals and other migratory animals often follow. This shift can increase the risk of whale entanglements in fishing gear.
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