Unexpected hope for millions as bleached coral reefs continue to supply nutritious seafood

Coral reef ecosystems support diverse small-scale fisheries – and the fish they catch are rich in micronutrients vital to the health of millions of people in the tropics, a new Lancaster University-led study reveals

Peer-Reviewed Publication


Macroalgal dominated reef

Researchers studying coral reefs damaged by rising sea temperatures have discovered an unexpected ‘bright spot’ of hope for communities who depend upon them for food security.

Coral reef ecosystems support diverse small-scale fisheries – and the fish they catch are rich in micronutrients vital to the health of millions of people in the tropics, a new Lancaster University-led study reveals.

And, counter-intuitively, following bleaching events that kill off coral and can transform the composition of reef ecosystems, reef fisheries can remain rich sources of micronutrients, even increasing in nutritional value for some minerals.

The findings, published today in the journal One Earth, show that the availability of micronutrients from coral reef small-scale fisheries may be more resilient to climate change than previously thought. This increased understanding is critical as continued global warming means coral bleaching events are becoming more frequent and more severe, placing greater stress on these vulnerable ecosystems.

Dr James Robinson, who led the study, said: “Our findings underline the continuing importance of these fisheries for vulnerable coastal communities, and the need to protect against over-fishing to ensure long-term sustainability of reef fisheries.”

The researchers also caution that while these fisheries have proved more resilient to climate change disturbance than expected, continued understanding of the long-term impacts of climate change to coral reef fisheries, and more data from other regions, are urgent priorities.

More than six million people work in small-scale fisheries that rely on tropical coral reefs. Their catches help to feed hundreds of millions of coastal people in regions with high prevalence of malnourishment, causing stunting, wasting and anaemia. However, until now, the nutritional composition of coral reef fish catches, and how climate change might affect the nutrients available from reef fisheries, was not known.

This study, led by scientists from Lancaster University and involving an international team of researchers from the Seychelles, Australia, Canada and Mozambique, benefitted from more than 20 years of long-term monitoring data from the Seychelles, where tropical reefs were damaged by a large coral bleaching event in 1998, killing an estimated 90% of the corals.

Following the mass-bleaching event, around 60% of the coral reefs recovered to a coral-dominated system, but around 40% were transformed to reefs dominated by seaweeds. These differences provided a natural experiment for the scientists to compare the micronutrients available from fisheries on reefs with different climate-driven ecosystem compositions.

The scientists, who used a combination of experimental fishing, nutrient analysis, and visual surveys of fish communities in the Seychelles, calculated that reef fish are important sources of selenium and zinc, and contain levels of calcium, iron and omega-3 fatty acids comparable to other animal-based foods, such as chicken and pork.

They also found that iron and zinc are more concentrated in fish caught on reefs that have been transformed after coral bleaching and are now dominated by macroalgae such as Sargassum seaweeds. These seaweeds have high levels of minerals, which, researchers believe, is a key reason why the algal-feeding herbivorous fishes found in greater numbers on transformed reefs contain higher levels of iron and zinc.

Dr Robinson said: “Coral reef fish contain high levels of essential dietary nutrients such as iron and zinc, so contribute to healthy diets in places with high fish consumption. We found that some micronutrient-rich reef species become more abundant after coral bleaching, enabling fisheries to supply nutritious food despite climate change impacts. Protecting catches from these local food systems should be a food security priority.”

The researchers believe the results underline the need for effective local management to protect the sustainability of reef fisheries, as well as policies that retain more of reef fish catches for local people and promote traditional fish-based diets. These can help reef fisheries to best contribute to healthy diets across the tropics.

Professor Christina Hicks, a co-author on the study, said: “Fish are now recognised as critical to alleviating malnutrition, particularly in the tropics where diets can lack up to 50% of the micronutrients needed for healthy growth. This work is promising because it suggests reef fisheries will continue to play a crucial role, even in the face of climate change, and highlights the vital importance of investing in sustainable fisheries management.”

The findings are outlined in the paper ‘Climate-induced increases in micronutrient availability for coral reef fisheries’.

The study’s authors include: James Robinson, Eva Maire, Nick Graham and Christina Hicks from Lancaster University; Nathalie Bodin from Seychelles Fishing Authority and Sustainable Ocean Seychelles; Tessa Hempson from James Cook University and Oceans Without Borders; Shaun Wilson from the Department of Biodiversity, Conservation and Attractions in Australia, and Oceans Institute, Australia; and Aaron MacNeil from Dalhousie University.

DOI: 10.1016/j.oneear.2021.12.005              


One Earth




Experimental study


Animal tissue samples


Climate-induced increases in micronutrient availability for coral reef fisheries



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January 8, 2022 6:05 pm

Amazing discovery

El-nino years produce coral bleaching and the corals, fish, seaweed and oceans that have been around for billions of years manage to survive and thrive

Reply to  Enthalpy
January 8, 2022 6:25 pm

It’s extraordinary isn’t it?

Every living species on the planet has somehow survived (or evolved since) climates of excessive heat, cold, rain and drought, for at least 100s of thousands of years … but a two degree temperature increase will destroy the planet.

Alarmists see nothing wrong with this apparent paradox.

Reply to  Harves
January 8, 2022 8:47 pm

Alarmists see nothing wrong with this apparent paradox.

It’s a bug not a feature. Sadly, it’s buried in a huge mess of spaghetti code and we’re not expecting a fix any time soon. 🙁 It appears that the loony left is irredeemable.

Reply to  Harves
January 8, 2022 9:46 pm

I don’t know how all the critters manage it with the constant dooming and interference by two legs-
Deep underground in Western Australia: first-ever millipede found with more than 1,000 legs. – YouTube

Pat from kerbob
Reply to  Enthalpy
January 8, 2022 6:58 pm

Continues to amaze me that anyone would believe a fraction of a degree temp rise could hurt corals in any sustained fashion.

If they were that delicate they would have vanished long ago, even amongst all the ups and downs of this interglacial

Gary Pearse
Reply to  Pat from kerbob
January 8, 2022 9:23 pm

Actually corals have been about the strongest survivors and adaptors of the animal kingdom. This most successful of lifeforms was present in the Ordovician 400 million years ago! There were no fish then.

They survived and multiplied into thousands of species. Modern coral number some 6000 species. They survived through the Mesozoic (Age of Dinosaurs) when global temperatures were 6C to 9C warmer than today and CO2 was up to 9 times present concentration in the atmosphere – it was warm and swampy into high latitudes.

Climate scientists seem unaware that the maximum temperature that open seawater surfaces can reach is, and was (!) 30°C because of evaporation, cloud formation and cooling thunderstorms. This is the deep dark secret about why the corals are not just surviving but flourishing for 400 million years!

Reply to  Gary Pearse
January 9, 2022 2:07 am

Bingo👍😃😃. this is the first time I have seen mentioned that the maximum temperature open sea water (The Oceans) can reach is around 30deg.C.
I have done some work on the reason for this and it is definitely true; but no one I repeat no one to date has responded to my repeated comments on this; there being a dearth of information and knowledge available on the internet.

I suspect that the reason for this is because the science involved is very inconvenient indeed for the CAGW MESSAGE; so the dead hand of the leftwing/marxist political agenda has seen to it that the whole subject of the Hydrological Cycle is suppressed for discussion.

The oceans comprise some 72% of the Earth’s surface so this temperature has a very marked influence on the global temperature.
However it goes further than this as the science applies equally to the water/atmosphere found in plant life which an area even greater than the Earth’s.
So there you have it: in the presence of adequate amounts of water there is a maximum universal temperature on Earth. However without this water the temperature can very much exceed this as will be found in deserts and places like Death Valley in California; hence, statistically we have the sort of global temperatures we observe.

Reply to  Enthalpy
January 9, 2022 7:12 am

Thank God for these dedicated “researchers” toiling away year after year making “visual surveys of fish communities “ in the Seychelles! Twenty years of all-expense-paid vacations under such grueling conditions

I want my money back

Reply to  Enthalpy
January 9, 2022 7:53 am

…all the while lying….by failing to acknowledge corals evolved to do exactly that

Paul Johnson
Reply to  Enthalpy
January 9, 2022 8:12 pm

As usual, “these fisheries have proved more resilient to climate change disturbance than expected”.

Geoff Sherrington
January 8, 2022 6:35 pm

It is pathetically easy to encapsulate iron, selenium, zinc, essential vitamins and so on, put them in small bottles and give them to impoverished nations. The cost is far less than putting them through the fishing cycle.
As a graduate from the first science class through James Cook university, I find it pathetic that such a bandwagon, shallow, inconsequential publication came out under that banner. It is time to learn and conduct some hard, meaningful science instead of scaring kids with trendy memes.
Mark is 1 1/2 out of 10. Geoff S

Tony Taylor
January 8, 2022 7:07 pm

“Unexpected hope for millions” – disaster for those who barrack for a climate catastrophe.

Reply to  Tony Taylor
January 8, 2022 8:19 pm

.08% of the world’s population is hardly a rounding error.

January 8, 2022 7:09 pm

”…following bleaching events that kill off coral..”

I stopped reading after that false statement. Bleaching is a defence mechanism for coral, it doesn’t kill it.

Reply to  aussiecol
January 8, 2022 7:27 pm

Peter Ridd who has been researching on the GBR for many years commented recently during an interview on Sky News Australia that the GBR is in excellent condition, that contrary to critics run off sediment from the land does not reach the GBR or does but in very small almost undetectable amounts.

And as we know from recent court hearings he has photographic records to support his claims including how the living coral has life cycles and after death recovery follows.

Last edited 1 year ago by Dennis
January 8, 2022 8:16 pm

You don’t need to read past “coral reefs damaged by rising sea temperatures”.

Gary Pearse
January 8, 2022 8:27 pm

Hmmm … so where was the zinc, iron and selenium before the bleaching? Well it was already in the fish, but particularly in shellfish, which fishermen also harvest.


Chris Nisbet
January 8, 2022 8:40 pm

“continued global warming means coral bleaching events are becoming more frequent and more severe”
Is this true?
How much more frequent? How much more severe?
‘Severe’ implies they’re a bad thing, but from what I can tell it’s not even certain that bleaching events are necessarily a bad thing. Would that be a fair assessment?

Zig Zag Wanderer
January 8, 2022 9:39 pm

So, everything is so much better than the CAGW Doomsday Death Cult acolytes predicted, and yet:

The researchers believe the results underline the need for effective local management to protect the sustainability of reef fisheries, as well as policies that retain more of reef fish catches for local people and promote traditional fish-based diets.

They can’t stop themselves from managing something that worked perfectly well without them for millions of years!

January 8, 2022 10:27 pm

They say “continued global warming means coral bleaching events are becoming more frequent and more severe” with no reference and no supporting information. Not that my searches are particularly efficient, but I cannot find any data anywhere that shows coral bleaching events becoming more severe. If there is no evidence of coral bleaching events becoming more frequent and more severe then the paper should be withdrawn or amended.
(Chris Nisbet January 8, 2022 8:40 pm picked up on this statement in the paper and asked if it is true. Unless someone can come up with the data that I could not find then the answer is that this statement in the paper is false.).

Jay Willis
Reply to  Mike Jonas
January 9, 2022 4:15 am

If you read the paper you will see that they provide many peer review references to support this assertion. This is probably more of a reflection of the terribly poor quality of much peer reviewed research on reefs, as highlighted by Peter Ridd, rather than the availability of good scientific research. This sort of long term tangled mess of crap science is why it is so difficult to pick apart this sort of paper.

January 9, 2022 1:31 am

may be more resilient to climate change than previously thought.

As my dad always used to say “You know what thought did”.
Explanations on the back of a postcard please.

January 9, 2022 4:41 am

in florida and the caribbean human impact is by far the biggest destroyer of coral . the reef off florida is in bad shape due to chemical runoff and direct human interaction while 90 miles away off cuba undisturbed reefs are thriving . the most degraded reefs in the caribbean are near human development while reefs in the hottest part of the caribbean around the san blas continue to thrive . is human presence a factor in the seychelles ?

January 9, 2022 5:35 am

So bleaching might be part of the natural life cycle?

January 9, 2022 8:39 am

What evidence is there of this? “Researchers studying coral reefs damaged by rising sea temperatures.”

Visible radiation bleaches coral, not minute changes in temperature. I’m pretty sure if you look into the evidence you will see that more visible radiation has been reaching the ocean and penetrating it to the depth of the coral. Place a Colored Tee Shirt on the Beach and you will see it rapidly lose its color. Cloud cover has been reduced over the oceans, more visible bleaching visible radiation is making it to the oceans. The radiation, not the warming is bleaching the coral. I’m pretty sure there are countless aquariums with water the same temperature as the oceans where the bleached coral is that have non-bleached coral. That would be an unbelievably easy experiment to test. Will climate scientists do it? Absolutely not.

January 9, 2022 8:41 am

Coral developed and evolved when CO2 was 7,000 ppm, so trying to point the finger at CO2 as the cause of bleaching denies 600 million years of history.

January 9, 2022 9:27 am

Uhhh, dopes. A reef cannot be killed.

A reef is an inanimate structural object on the sea bottom.

Living corals can be killed, but that horribly prejudicial and technically ridiculous term “bleaching” does not kill coral. It’s simply a changing of the guard, as live corals cast off one population of co-dependent algae substituting a fresh one. Regardless, the reef always remains .. and new coral polyps can quickly and easily repopulate the carbonate reef, and it does not matter to the corals whether the underlying corals are live or dead … and in fact only the surficial populations of corals are living anyway, not the stuff buried deep inside large corals like brain corals.

The fish don’t care, they’ll eat whatever is available. And some fish species actually eat the skeletal coral reefs themselves, generating “coral sand” poop in the process that over time becomes immensely thick layers of sand, creating huge sand banks such as the Bahamas Bank, where the sand is upwards of two thousand feet or more thick on the underlying rock bottom – again, all made up of the remains of formerly living coral..

Dave Andrews
Reply to  Duane
January 9, 2022 10:00 am

“A reef cannot be killed”

Yep. The US tried to nuke Bikini Atoll to death but did not succeed!

January 9, 2022 11:03 am

Go on the following Australian site and look at the reef status in the GBR. Most reefs are doing quite well and long term damage from bleaching has been minimal. Most of the worst damage has been from cyclones and crown-of-thorns sea star outbreaks.


Reply to  Cam
January 10, 2022 4:31 am

What a brilliant link.

michael hart
January 9, 2022 1:19 pm

“This study, led by scientists from Lancaster University and involving an international team of researchers from the Seychelles, Australia, Canada and Mozambique…”

I lived in Lancaster for 13 years. There would have been nothing better than to go off researching tropical coral reefs during the dark months. I’m a terrible cynic, but these people only enter the subject for the “field work”.

Andy H
January 10, 2022 1:05 am

It is almost as if the coral was only providing an environment that the other creatures were living in. Take away the living part of the coral and the environment is still there.

What a great opportunity to re-site rarer corals into the bleached coral environment and farm the prettier ones.

Michael in Dublin
January 11, 2022 9:04 am

In 2008 Professor Steve Jones published Coral: A Pessimist in Paradise.It was definitely one of the alarmist genre of books. At the time, I read the book twice to see how he undermined his argument and contracted himself. It was a colorful book with many anecdotes and the chapters each had a catchy title – not unlike Aesop’s Fables.

This is the approach I always take, as a non-scientist, and that is to look at the logic, examining the cohesion and coherence of the writing. When problems are clearly evident in these areas then the science is likely to be flawed. I have also noticed how alarmists hate having these problems pointed out and respond with ad hominems like accusing the questioner of being a climate denier.

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