Trouble in the waters: What El Niño means for marine life

It’s official: El Niño is here, and it’s going to intensify as we move through the year. We talk a lot about what El Niño means for weather patterns, but what about its impacts below the waves — specifically on the life that resides there?

The Pacific now and what’s coming next

Waters in a zone of the eastern and central Pacific Ocean near the equator have warmed to more than 0.5 degrees Celsius above average. This, plus the circulation of winds and distribution of showers and storms over that area now "reflect the onset of El Niño conditions," according to NOAA’s Climate Prediction Center.

There are also already several marine heatwaves ongoing in the Pacific that have been in place since before the arrival of El Niño, according to Dr. Andrew Leising, a research oceanographer with NOAA’s Southwest Fisheries Science Center, meaning water is already warm for a lot of the region.

(MORE: Pacific ‘Blob’: Its impact and does El Niño supercharge it?)

The marine heat wave outlook for August also shows two distinct areas more likely to experience a marine heat wave in locations similar to what we are seeing now: one in the Pacific and one near southern California.

The marine heat waves are going to remain impactful as we move into the peak summer months, and the August marine heat wave outlook from NOAA looks fairly similar to 2015’s infamous “Blob,” according to Dr. Leising.

But keep in mind that these marine heat waves are in addition to the developing El Niño, which is still in its very early stages and only expected to grow stronger.

“We're looking for the El Niño conditions that are already in place to intensify over the next several months. There’s an over 60% chance, 63% chance specifically, of very strong El Niño conditions materializing by the upcoming winter season,” warns Ariel Cohen, meteorologist in charge for the Los Angeles National Weather Service office.

This has experts concerned about the health of the Pacific’s marine ecosystems in the near future. The impacts of El Niño will be compounded by the marine heat waves already in place, which can mean trouble for marine life. And while El Niño doesn’t guarantee specific patterns and impacts, a stronger El Niño does improve the odds of those impacts.

What to expect from marine life and what it means for us

One of the main impacts to watch for from the situation developing in the Pacific Ocean requires us to start from the very bottom (of the food chain, that is).

Marine heat waves cause plankton, the base of the marine food web, to be less productive. 

Then you add in El Niño, which causes a decrease in upwelling. Upwelling is a process that provides shorelines with fresh, nutrient-rich water from the depths to the surface, so less upwelling means there will be less phytoplankton near the coast.

Decreases in plankton cause cascading impacts throughout the ecosystem, because impacts to phytoplankton cause impacts to the fish that eat the phytoplankton and then to the fish that eat those fish. 

This leads the overall system to be less productive and healthy.

When conditions change, and there’s less food available, marine life may start moving into areas where it is not typically found, such as regions that are usually too cold.

The search for food ultimately compresses marine mammals and migratory species toward the coast, where there is an increased risk of vessel strikes and entanglements, which can be deadly.

Harmful algal blooms are also more likely during El Niño events, which can be toxic for marine life.

When you add those key impacts together, you get a picture of a potentially dangerous situation for ecosystems in the Pacific Ocean, especially because the El Niño is going to follow heatwaves already in place and can last a considerable amount of time.

“We need to be ready to take care of communities and the different creatures in the waters that might be impacted over the long haul,” says Jeff Flocken, the president and CEO of the Aquarium of the Pacific.

The West Coast of the United States has what is known as a “blue economy,” meaning the economy relies heavily on a healthy marine ecosystem.

“We have fisheries, and we have an ecotourism industry that's thriving. Right off our waters here outside of Los Angeles and Orange County, we have almost hourly whale and dolphin watches going out, bringing tourists out to see these ecosystems, and if they're not thriving, if there's trouble, that's going to directly impact the economy,” explains Flocken.

So it’s not just for the sake of marine life that we need to pay attention and be concerned. It’s also for the sake of the communities that live near and rely on that ecosystem, which may be in trouble if the worst-case scenario plays out. 

The silver lining

But it’s important to take note of what isn’t warm yet. It may not look like much, but the waters just offshore of the Pacific Coast are actually cooler than normal due to the upwelling occurring in the region.

The cooler waters now will help provide a buffer for animals that live in the area by delaying the hazardous conditions and shortening the time spent under those conditions.

“What we’ve seen in the past when we have these large marine heat waves or after an El Niño is our system actually has a lot of resiliency and is usually able to come back fairly well after these events,” says Dr. Liesing.

What we should be doing now

There’s nothing we can do to prevent a marine heat wave or bring about an early end to El Niño, but there are ways we can prepare for a potentially harmful situation for our marine ecosystems.

A great place to start is to know what to do if you come across a marine or coastal species in distress.

“Make sure to contact the authorities, and they'll be able to work with rescuers together to make sure to take care of that animal,” urges Flocken. 

We also need to know that there is a lot we don’t know right now. 

Data collection is important in the coming months, so experts will have a better understanding and ability to handle future events similar to the one that’s arriving now.

Sara Tonks is a content meteorologist with weather.com and has a bachelor’s and a master’s degree from Georgia Tech in Earth and Atmospheric Sciences along with a master’s degree from Unity Environmental University in Marine Science.