I Studied What Happens To Reef Fish After Coral Bleaching. What I Saw Still Makes Me Nauseous

I Studied What Happens To Reef Fish After Coral Bleaching. What I Saw Still Makes Me Nauseous Victor Huertas, Author provided Jodie L. Rummer

The Great Barrier Reef is suffering its third mass bleaching event in five years. It follows the record-breaking mass bleaching event in 2016 that killed a third of Great Barrier Reef corals, immediately followed by another in 2017.

While we don’t know if fish populations declined from the 2016 bleaching disaster, one 2018 study did show the types of fish species on some coral reefs changed. Our study dug deeper into fish DNA.

I was part of an international team of scientists that, for the first time, tracked wild populations of five species of coral reef fish before, during, and after the 2016 marine heatwave.

From a scientific perspective, the results are fascinating and world-first.

I Studied What Happens To Reef Fish After Coral Bleaching. What I Saw Still Makes Me Nauseous Marine heatwaves are now becoming more frequent and more severe with climate change. Corals are bleaching, as pictured here. Jodie Rummer, Author provided

We used gene expression as a tool to survey how well fish can handle hotter waters. Gene expression is the process where a gene is read by cell machinery and creates a product such as a protein, resulting in a physical trait.

We know many tropical coral reef fish are already living at temperatures close to their upper limits. Our findings can help predict which of these species will be most at risk from repeated heatwaves.

But from a personal perspective, I still feel nauseous thinking about what the reef looked like during this project. I’ll probably feel this way for a long time.

Rewind to November 2015

We were prepared. Back then we didn’t know the reef was about to bleach and lead to widespread ecological devastation. But we did anticipate that 2016 would be an El Niño year. This is a natural climate cycle that would mean warm summer waters in early 2016 would stick around longer than usual.

But we can’t blame El Niño – the ocean has already warmed by 1°C above pre-industrial levels from continued greenhouse gas emissions. What’s more, marine heatwaves are becoming more frequent and severe with climate change.

Given this foresight, we took some quick liver biopsies from several coral reef fish species at our field site in December 2015, just in case.

I Studied What Happens To Reef Fish After Coral Bleaching. What I Saw Still Makes Me Nauseous Coral bleaching at Magnetic Island, March 2020. Victor Huertas, Author provided

A couple months later, we were literally in hot water

In February 2016, my colleague and I were based on Lizard Island in the northern part of the Great Barrier Reef working on another project.

The low tides had shifted to the afternoon hours. We were collecting fish in the shallow lagoon off the research station, and our dive computers read that the water temperature was 33°C.

We looked at each other. These are the temperatures we use to simulate climate change in our laboratory studies for the year 2050 or 2100, but they’re happening now.

Over the following week, we watched corals turn fluorescent and then bone-white.

The water was murky with slime from the corals’ immune responses and because they were slowly exuding their symbiotic zooxanthellae – the algae that provides corals with food and the vibrant colours we know and love when we think about a coral reef. The reef was literally dying before our eyes.

I Studied What Happens To Reef Fish After Coral Bleaching. What I Saw Still Makes Me Nauseous A third of the corals on the Great Barrier Reef perished after the 2016 heatwave. Jodie Rummer, Author provided

Traits for dealing with heatwaves

We sampled fish during four time periods around this devastating event: before, at the start, during, and after.

Some genes are always “switched on”, regardless of environmental conditions. Other genes switch on or off as needed, depending on the environment.

If we found these fish couldn’t regulate their gene expression in response to temperature stress, then the functions – such as metabolism, respiration, and immune function – also cannot change as needed. Over time, this could compromise survival.

The plasticity (a bit like flexibility) of these functions, or phenotypes, is what buffers an organism from environmental change. And right now, this may be the only hope for maintaining the health of coral reef ecosystems in the face of repeated heatwave events.

So, what were the fish doing?

We looked at expression patterns of thousands of genes. We found the same genes responded differently between species. In other words, some fish struggled more than others to cope with marine heatwaves.

I Studied What Happens To Reef Fish After Coral Bleaching. What I Saw Still Makes Me Nauseous Ostorhinchus doederleini, a species of cardinalfish, is bad at coping with marine heatwaves. Göran Nilsson, Author provided

The species that coped the least was a nocturnal cardinalfish species (Cheilodipterus quinquelineatus). We found it had the lowest number of differentially expressed genes (genes that can switch on or off to handle different stressors), even when facing the substantial change in conditions from the hottest to the coolest months.

In contrast, the spiny damselfish (Acanthochromis polyacanthus) responded to the warmer conditions with changes in the expression of thousands of genes, suggesting it was making the most changes to cope with the heatwave conditions.

What can these data tell us?

Our findings not only have implications for specific fish species, but for the whole ecosystem. So policymakers and the fishing industry should screen more species to predict which will be sensitive and which will tolerate warming waters and heatwaves. This is not a “one size fits all” situation.

I Studied What Happens To Reef Fish After Coral Bleaching. What I Saw Still Makes Me Nauseous One of the species that showed the least amount of change under warming was Cheilodipterus quinquelineatus. Moises Antonio Bernal de Leon, Author provided

Fish have been on the planet for more than 400 million years. Over time , they may adapt to rising temperatures or migrate to cooler waters.

But, the three recent mass bleaching events is unprecedented in human history, and fish won’t have time to adapt.

My drive to protect the oceans began when I was a child. Now it’s my career. Despite the progress my colleagues and I have made, my nauseous feelings remain, knowing our science alone may not be enough to save the reef.

The future of the planet, the oceans, and the Great Barrier Reef lies in our collective actions to reduce global warming. What we do today will determine what the Great Barrier Reef looks like tomorrow.The Conversation

About The Author

Jodie L. Rummer, Associate Professor & Principal Research Fellow, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Related Books

Life After Carbon: The Next Global Transformation of Cities

by Peter Plastrik , John Cleveland
1610918495The future of our cities is not what it used to be. The modern-city model that took hold globally in the twentieth century has outlived its usefulness. It cannot solve the problems it helped to create—especially global warming. Fortunately, a new model for urban development is emerging in cities to aggressively tackle the realities of climate change. It transforms the way cities design and use physical space, generate economic wealth, consume and dispose of resources, exploit and sustain the natural ecosystems, and prepare for the future. Available On Amazon

The Sixth Extinction: An Unnatural History

by Elizabeth Kolbert
1250062187Over the last half-billion years, there have been Five mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Scientists around the world are currently monitoring the sixth extinction, predicted to be the most devastating extinction event since the asteroid impact that wiped out the dinosaurs. This time around, the cataclysm is us. In prose that is at once frank, entertaining, and deeply informed, New Yorker writer Elizabeth Kolbert tells us why and how human beings have altered life on the planet in a way no species has before. Interweaving research in half a dozen disciplines, descriptions of the fascinating species that have already been lost, and the history of extinction as a concept, Kolbert provides a moving and comprehensive account of the disappearances occurring before our very eyes. She shows that the sixth extinction is likely to be mankind's most lasting legacy, compelling us to rethink the fundamental question of what it means to be human. Available On Amazon

Climate Wars: The Fight for Survival as the World Overheats

by Gwynne Dyer
1851687181Waves of climate refugees. Dozens of failed states. All-out war. From one of the world’s great geopolitical analysts comes a terrifying glimpse of the strategic realities of the near future, when climate change drives the world’s powers towards the cut-throat politics of survival. Prescient and unflinching, Climate Wars will be one of the most important books of the coming years. Read it and find out what we’re heading for. Available On Amazon

From The Publisher:
Purchases on Amazon go to defray the cost of bringing you InnerSelf.comelf.com, MightyNatural.com, and ClimateImpactNews.com at no cost and without advertisers that track your browsing habits. Even if you click on a link but don't buy these selected products, anything else you buy in that same visit on Amazon pays us a small commission. There is no additional cost to you, so please contribute to the effort. You can also use this link to use to Amazon at any time so you can help support our efforts.

 

enafarzh-CNzh-TWdanltlfifrdeiwhihuiditjakomsnofaplptruesswsvthtrukurvi

follow InnerSelf on

facebook-icontwitter-iconrss-icon

 Get The Latest By Email

{emailcloak=off}

LATEST VIDEOS

Talking About Energy Change Could Break The Climate impasse
Talking About Energy Change Could Break The Climate Impasse
by InnerSelf Staff
Everyone has energy stories, whether they’re about a relative working on an oil rig, a parent teaching a child to turn…
Crops Could Face Double Trouble From Insects And A Warming Climate
Crops Could Face Double Trouble From Insects And A Warming Climate
by Gregg Howe and Nathan Havko
For millennia, insects and the plants they feed on have been engaged in a co-evolutionary battle: to eat or not be…
To Reach Zero Emissions Government Must Address Hurdles Putting People Off Electric Cars
To Reach Zero Emissions Government Must Address Hurdles Putting People Off Electric Cars
by Swapnesh Masrani
Ambitious targets have been set by the UK and Scottish governments to become net-zero carbon economies by 2050 and 2045…
Spring Is Arriving Earlier Across The US, And That's Not Always Good News
Spring Is Arriving Earlier Across The US, And That's Not Always Good News
by Theresa Crimmins
Across much of the United States, a warming climate has advanced the arrival of spring. This year is no exception.
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
by Alan N Williams, et al
The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that without a substantial decrease…
A Georgia Town Gets Half Of Its Electricity From President Jimmy Carter's Solar Farm
A Georgia Town Gets Half Of Its Electricity From President Jimmy Carter's Solar Farm
by Johnna Crider
Plains, Georgia, is a small town that is just south of Columbus, Macon, and Atlanta and north of Albany. It is the…
Majority of US Adults Believe Climate Change Is Most Important Issue Today
by American Psychological Association
As the effects of climate change become more evident, more than half of U.S. adults (56%) say climate change is the…
How These Three Financial Firms Could Change The Direction Of The Climate Crisis
How These Three Financial Firms Could Change The Direction Of The Climate Crisis
by Mangulina Jan Fichtner, et al
A silent revolution is happening in investing. It is a paradigm shift that will have a profound impact on corporations,…

LATEST ARTICLES

Heatwaves Too Hot And Wet For Human Life Are Here
Heatwaves Too Hot And Wet For Human Life Are Here Now
by Tim Radford
Lethal heatwaves carrying air turned too hot and wet to survive are a threat which has arrived, thanks to climate…
How Dangerous Is Low-level Radiation To Children?
How Dangerous Is Low-level Radiation To Children?
by Paul Brown
A rethink on the risks of low-level radiation would imperil the nuclear industry’s future − perhaps why there’s never…
What We Do Now Could Change Earth's Trajectory
What We Do Now Could Change Earth's Trajectory
by Pep Canadell, et al
The numbers of people cycling and walking in public spaces during COVID-19 has skyrocketed.
Marine Heatwaves Spell Trouble For Tropical Reef Fish — Even Before Corals Die
Marine Heatwaves Spell Trouble For Tropical Reef Fish — Even Before Corals Die
by Jennifer M.T. Magel and Julia K. Baum
Despite the many challenges facing the world’s oceans today, coral reefs remain strongholds of marine biodiversity.
Warnings of Worse-Than-Usual Hurricane Season Point to Trouble Ahead
Warnings of Worse-Than-Usual Hurricane Season Point to Trouble Ahead
by Eoin Higgins
Hurricane season is about to start and its risks will only grow and potentially compound any impacts from the pandemic.
Australia, It's Time To Talk About Our Water Emergency
Australia, It's Time To Talk About Our Water Emergency
by Quentin Grafton et al
There’s another climate change influence we must also face up to: increasingly scarce water on our continent.
Fossil Fuels Are Heading Down, But Not Yet Out
Fossil Fuels Are Heading Down, But Not Yet Out
by Kieran Cooke
Renewable energy is making rapid inroads into the market, but fossil fuels still wield enormous global influence.
Human Action Will Decide How Much Sea Levels Rise
Human Action Will Decide How Much Sea Levels Rise
by Tim Radford
Sea levels will go on rising, because of human action. By how much, though, depends on what humans do next.