"We're constantly learning from the Earth system, and that allows us to be better prepared and do something about El Niño," said Duke's Jean-Philippe Gibert about protecting coral reefs, fisheries and our ocean ecosystems.
How Will This El Niño Affect Fisheries and Oceans?
Throughout the summer and into fall this year, El Niño has been gaining strength. El Niño is a climate phenomenon where, every few years, the Pacific Ocean becomes warmer, influencing weather and climate patterns on a global scale, explains Duke University expert Shineng Hu.
Much of the conversation surrounding the El Niño impacts on the United States has been about which areas will have wetter winters than usual (Southern U.S.) and where will winter be drier (Northwest and Northeast U.S.).
But El Niño is, at its core, an ocean event with consequences that extend far beyond a country or season. In a recent editorial in the Proceedings of the National Academy of Sciences, an international group of researchers called for collaboration to better understand this El Niño’s effects on marine ecosystems, and on the people who rely on them.
Lead author John F. Bruno, marine ecologist at the University of North Carolina at Chapel Hill, and co-author Jean-Philippe Gibert, Joanne W. Markman and A. Morris Williams, Jr. Associate Professor of Biology, dive into the effects of El Niño on the ocean — and what we can do about them.
This interview has been edited for length and clarity.
What is the impact of El Niño on marine ecosystems?
Jean-Philippe Gibert: If it's too cold or too hot, there's no life. El Niño moves huge amounts of heat around the globe, making some places unseasonably hot. That has giant effects on all organisms experiencing those conditions, including in the way they interact with one another.
To mention one example: predators have to deal with this new thermal stress, so some prey species are going to experience less predation, while others will experience more of it. Species experiencing less predation can become more abundant and outcompete others. That leads to these cascading, or knock-on, effects of temperature on food webs, and these effects can be quite unpredictable.
John F. Bruno: El Niño affects everything. It reduces fishery yields in many cases, because a lot of fishes are really sensitive to high temperatures, so fishermen can be harmed in economic terms. Coastal communities can be harmed economically, in places where people depend on seafood literally for their survival. That's really impactful.
Gibert: Fisheries, great example. When we warm those fisheries, there can be a number of effects, including reduced reproduction. These fish might lose or even gain a top predator who are themselves escaping heat events elsewhere. Now they're eating the fish that you're relying on, and that same fish is also reproducing less because of the heat. Double whammy.
The consequences are worldwide. They're complex. Ocean ecosystems are inherently open, meaning that they are more likely to be perturbed by things that happen elsewhere on the planet, and also to influence things that happen elsewhere on the planet. The impacts on terrestrial ecosystems tend to be more localized.
How bad does El Niño look this year?
Gibert: By virtue of El Niño heating the planet on a background of an already warming planet, systems that are receiving the brunt of that heating can reach a tipping point. Once you collapse a fishery, for example, it's really hard to recover.
Bruno: We see coral bleaching being associated with El Niño and really high temperatures. We've all heard about the mass bleaching on the Great Barrier Reef, across the Caribbean, across the world really. So, we're expecting some pretty severe coral bleaching next summer.
But there are also winners.
There has been some really cool work at the Duke Experimental Forest that shows poison ivy is a climate change winner. The warmer it is, and the more CO2 there is in the atmosphere, the more poison ivy thrives.
We see the same thing in the ocean. There's been reports all around the world of jellyfish blooms and algal blooms. Weedy species — slimy seaweeds, bacteria — tend to benefit from these warmer conditions.
Gibert: We are on a temperature uptrend anyways, so — super El Niño or not — the consequences of this El Niño are still going to be pretty large.
How should we respond to the super El Niño this year?
Gibert: Just because there is a super El Niño coming doesn’t mean we should feel sorry for ourselves and not do anything about it. There are many things we can do.
We can adjust fishing quotas. We can dynamically dial in the right amount of catch that we allow in zones of economic importance, to build some resilience in the socio-economic system. The worst thing we can do is have a short-term frame to deal with these processes.
We want to make sure that with our colleagues, as a community, we are thinking globally and collectively about the things we can do in preparation before, during, and after El Niño.
Bruno: We are trying to get people to start thinking about how to prepare for it in terms of mitigating impacts. That will actually increase fishery yields in the long run because it’ll allow species to recover much more quickly after El Niño.
The challenge of the coming El Niño is to make changes that we know are effective.
We're making the point to “get out there, do whatever you're going to do, but quantify it.” Report what you're doing and report the state of the population before and after. Have a control site — a place where you don't do whichever intervention you are planning on doing — and then see what works.
What are your hopes for the future of El Niño research and response?
Gibert: The best thing people can have is a long-term mindset as opposed to a short-term one. We're constantly learning from the Earth system, and that allows us to be better prepared and do something about El Niño. We're all using this knowledge we've generated to think about what we can do next time a huge heat wave comes.
Bruno: Some of this thinking is happening at conferences, but these conferences are rarely interdisciplinary. We need a broader, interdisciplinary approach.
Gibert: Building resilience in an open system like the oceans requires cross border collaboration. Supporting science across borders is majorly important for the future of El Niño research, and to our ability to respond to it.
