Climate change has degraded productivity of shelf sea food webs

University of Plymouth

IMAGE: A mixture of dinoflagellates and diatoms from the L4 coastal monitoring site off Plymouth, England. view more  Credit: Claire Widdicombe

A shortage of summer nutrients as a result of our changing climate has contributed to a 50% decline in important North East Atlantic plankton over the past 60 years.

New research, published in Global Change Biology, shows that larger, nutritious plankton – vital to support fish, seabirds and marine mammals – are being replaced by tiny, primary producers that are of poorer food quality.

Changes from cloudier and wetter summers to longer periods of sunshine and drought have led to decreasing iron and nutrient supply to surface waters. This results in an increased period of suboptimal feeding conditions for zooplankton at a time of year when their metabolic demand is at its highest.

In some areas, large phytoplankton are being almost completely replaced by picoplankton, especially the cyanobacterium Synechococcus, that flourishes when iron and nitrogen levels in surface waters are very low.

However, its small size and lack of essential biomolecules mean it is unable to function in the same way as larger, more nutritious phytoplankton – a vital primary producer of omega-3 – and cannot sustain shelf sea food webs efficiently.

With Synechococcus prominent from the tropics to the Arctic, and its abundance increasing worldwide, scientists suggest that competition for scarce summer nutrients will become a key force in structuring shelf sea food webs. Shelf seas provide around 80% of the world’s wild-captured seafood, and changes in their productivity will have major effects on humans.

The study was led by scientists at the University of Plymouth (funded through the Natural Environment Research Council’s Shelf Sea Biogeochemistry Programme), working with colleagues from Plymouth Marine Laboratory, the Marine Biological Association, and the University of Southampton. It brought together experts from a range of fields including trace metal analysis, plankton taxonomy, and satellite data.

Lead author Dr Katrin Schmidt, a plankton ecologist in the University of Plymouth’s School of Geography, Earth and Environmental Sciences, said: “Zooplankton such as copepods are considered beacons of climate change, and the ~50% decline in their abundance over the last six decades is worrying. Our study is the first to provide a mechanism for such a wide-spread decline, and this understanding is essential to project future responses to climate change. We also need to explore the wider impacts and whether the changing nutrient supply could, for example, lead to reductions in omega-3 within the entire food chain.”

The study was based on an area measuring 2,000km by 1,500km in the North East Atlantic, and used a combination of data generated by satellites and the MBA’s Continuous Plankton Recorder (CPR) survey. It allowed scientists to identify both longer and shorter-term trends, the spatial extent of any changes and the months that are most affected.

It also used intensive field observations of the phytoplankton community and, by linking the two scales, provided a conceptual model of why the classical food web is increasingly under threat in temperate coastal and shelf areas.

In combination, both satellite and CPR data show similar changes over the longer (1958-2017) and shorter (1997-2018) terms. Between May and August/September in those years, numbers of diatoms, dinoflagellates and total copepods have all declined, while the proportion of picophytoplankton has increased.

Co-author Dr Luca Polimene, Senior Marine Ecosystem Modeller at Plymouth Marine Laboratory, said: “The increasing dominance of small phytoplankton species might have a broad impact on the marine ecosystem. Other than altering the food chain as suggested in this study, it could also change the biological carbon pump modifying the capacity of the ocean to store carbon. We need to make sure that the shift between large to small phytoplankton species is well captured by marine ecosystem models if we want to reliably simulate future oceans.”

David Johns, Head of the Continuous Plankton Recorder Survey, added: “While the CPR Survey samples the larger plankton community, declines in some key groups over past decades can be linked to changes in the smallest plankton that are driven by climate change. We have previously witnessed direct climate impacts on the plankton community, from seasonality (temporal) to large scale movements (spatial), via changes in temperature. This study demonstrates a knock-on effect through the food web, and it is only by continuing our monitoring that we will identify multiple stressors acting on our marine environment, and hopefully sustain and protect our productive oceans.”


From EurekAlert!

0 0 votes
Article Rating
Newest Most Voted
Inline Feedbacks
View all comments
June 7, 2020 10:26 pm

Global cooling is coming.

Joel O'Bryan
June 7, 2020 10:51 pm

The levels of pollution from phosphates flowing into rivers and then into the seas have dramatically decreased during that period. Starting the late 1980’s phosphorous discharges have decreased dramatically in Eastern US streams and watersheds. See graphs in below links. Not climate change. Reductions in “pollutants.”

Reply to  Joel O'Bryan
June 8, 2020 1:28 am

Ah interesting. NPK fertiliser is plant food of course. Nitrogen potassium phosphorous… and plankton is a plant. …

It is a shame science has been so corrupted by the climate change bullshit.

Reply to  Matt_S
June 8, 2020 2:43 am

This is a far more plausible explanation than the one given in the paper.

It is well known in Britain that the largest crabs and lobsters are to be found around sewage outfalls.

Reply to  Graemethecat
June 8, 2020 3:04 am

And at Hinkley point, where the water is warmer….

Charles Higley
Reply to  Graemethecat
June 8, 2020 6:20 am

Up in Maine, Somes Sound at Great Harbor is a huge flush twice a day. We used to have sewage systems on the outer islands that dumped into the ocean. The small number of year-round residents and summer people hardly equalled the herds of sheep on those islands before they were made into summer places. Lobstering was good and all kinds of sealife abounded.

Then, in the 70s they made everybody put in septic systems or an electric-based cloves multrum-type fermenters (which meant bringing over shore power, which cost a small fortune). In less than two years, the sealife around the islands dropped off as the fertilizers were gone.

One cow is equivalent to about 12 humans and an average whale worth about 20 cows (240 humans. Whales used to abound in the area and these islands were only equivalent to one or two whales. It serves to have some perspective. ‘Still a question if all that expense and trouble was worth it, particularly to the fishermen.

Reply to  Joel O'Bryan
June 8, 2020 5:32 am

Yep, i seem to remember reading about how we were destroying the oceans with run-off fertilizer and household waste(soap etc) leading to massive plankton blooms which would reduce oxygen levels and suffocate the fish etc, in the late 80’s.
Could be that now that we have ‘cleaned up our act’ nature is returning to ‘normal’?

But no, humans = BAD!

What a depressing time we’re going through now.
On the bright side, as we seem to be running out of other peoples money at an alarming rate due to lockdowns, maybe all these privileged academic types will soon have to find a real job and become a productive part of the economy rather than a net drain.
One can always hope.

Stay sane,


Reply to  Willem69
June 9, 2020 12:21 am

Yeah, lets face it, humans are part of nature. As we live off the actions of other animals so they live off us. Our cities are cliffs for nesting birds, our waste dumps a feast, and out ex industrial sites (quarries) become wildlife sanctuaries. We never did leave nature, and never will.

Reply to  Joel O'Bryan
June 8, 2020 5:45 am

Joel…you hit it

They go back 60 years…claim that was normal….and things are getting worse

…they never consider it was 60 years ago that wasn’t normal..messes up their agenda

Loren Wilson
Reply to  Joel O'Bryan
June 9, 2020 9:48 am

There was an earlier paper by a researcher who was able to increase the Pacific salmon population by seeding the ocean with iron. This was based on the observation that the salmon increased after an eruption that put ash into the ocean. The mechanism is the same – iron is a necessary nutrient of the plankton, which then helps everything above it on the food change.

The idea that our effluent (untreated sewage) helped plankton growth has merit and could be investigated by comparing similar regions of the ocean offshore of an area with good sewage treatment with one that does not.

This paper also demonstrates that we need much more than fifty years of data to say that we understand these cycles.

Ray G
June 7, 2020 10:59 pm

Here we go, conseptual models again

June 7, 2020 11:03 pm

Scientists are beginning to warn that global cooling is coming.

Reply to  Michael
June 8, 2020 10:24 am

Source, links that “Scientists are beginning to warn that global cooling is coming.”

Coeur de Lion
June 7, 2020 11:12 pm

Must have been devastating during the MWP. Reversed during the LIA, I guess.

June 7, 2020 11:25 pm

Anthony understands.

June 7, 2020 11:25 pm

If this was true and “vital” then why haven’t all the fish and everything that feeds on them died?

June 7, 2020 11:27 pm

“Changes from cloudier and wetter summers to longer periods of sunshine and drought have led to decreasing iron and nutrient supply to surface waters. This results in an increased period of suboptimal feeding conditions for zooplankton at a time of year when their metabolic demand is at its highest”

This is really fine research, sir. Thank you. You are a class unto yourself. And here is a more complete description of that class of research.

June 7, 2020 11:53 pm

“..decline in important North East Atlantic plankton over the past 60 years.“
What was a stumpy barren hillside in my childhood, where my grandfather told me had been a small forest when he was younger, before beavers moved in, is now a small forest again that I show my grandchildren. Things change in nature over 60 years. Scientists need to get over it.

June 8, 2020 1:25 am

“Changes from cloudier and wetter summers to longer periods of sunshine and drought” Where on earth do they get their data from?

Climate change is supposed to increase rainfall, and in some areas (Scotland, in the ares of the study) there has been a slight increase.

Or so the Met office tells us anyway. Perhaps one of them is lying….

old construction worker
June 8, 2020 4:22 am

Unlike humans, in a short amount of time, fish will move to where there is a good food chain.

Peta of Newark
June 8, 2020 4:27 am

For the UK, with its history of iron mining, there will be no shortage of iron in the water.
And as we all see on TV & Interweb, (flash) flood waters that are orange/brown in colour. THAT colour is Iron.

The mud/silt in those floods is also loaded with everything plants need to grow -it is coming from well fertilised farmland after all.

So, what’s left?
1) Are the critters being poisoned – especially from the various Heavy Metals that somehow get flushed down toilets. Are they being poisoned from anti-barnacle/corrosion treatments applied to the vast amount of shipping that goes past there? or from the ships emptying their tanks?

2) Are they suffering the same ‘fate’ that befell Scandinavian forests when Acid Rain was devised/invented/raved about?
Because, the Acid Rain was actually working as fertiliser for the trees in Scandinavia especially the sulphur it contained. It is essential for UK farmers to apply sulphur fertiliser to almost every crop they grow nowadays.
30+ years ago, it was unknown to do that – it was taken for granted then because it simply fell down out of the sky with the rain. But UK heavy industry is now all gone and the power stations were all ‘scrubbed’ and are now closed.
Also all the nutrition that previously came from the burning of agricultural crop residues (straw).
Soot basically – ask almost any serious gardener/horticulturist about its fertilising value.

THAT is what the critters are missing – pollution.
Funny old world innit…………..

Reply to  Peta of Newark
June 8, 2020 10:26 am

Soot is a very dangerous form of pollution, extremely hazardous on the lungs. Your comments are ridiculous.

Reply to  posa
June 8, 2020 4:20 pm

Soot is not good for people, and by extension, mammals, perhaps even animals. It may very well be good for plants. Certainly the soil amendments that farmers apply are good for their plants but would be, at best, useless, more likely, toxic, to me.

Loren Wilson
Reply to  posa
June 9, 2020 9:57 am

Last year it came out that the lab tech doing all the PM10 research in the US for the big group that provided data to the CDC had been falsifying the data for years. While we should be cautious and protect people from breathing smoke, some real, verifiable, duplicated research needs to be done to support the current claims. The best way to help people not breathe soot is to provide them with inexpensive natural gas.

High Treason
June 8, 2020 5:05 am

“Climate change”- 2 nouns that need a qualifying pronoun to have a real meaning. Without qualification, the term means nothing or anything you wish. Is it getting warmer or cooler? Which one? Is it man made or natural?? If it is natural, as it has been for the past 4 1/2 billion years, then so what- climate changes. Is it even dangerous? Will radical changes in human behaviour make much difference to the climate anyway?
The whole thing is a semantic manipulation that is designed to not only swindle trillions out of us but also destroy the very basis of our civilisation.

June 8, 2020 5:22 am

The rise of advanced wastewater treatment in industry and municipalities, and improved agricultural practices. So now the ocean critters protest. Green lives matter.

Just Jenn
June 8, 2020 5:31 am

Omega 3 is the ringer in this article.

You know the supplement that is the “miracle cure”, its capped and bottled by companies seining for zooplankton.

Add in less pollution, massive harvesting and what have you got? Less.

This is about humans, but it has to do with Omega 3 more IMO.

June 8, 2020 7:59 am

If the problem is a shortage of iron, that’s easily solvable.

June 8, 2020 11:08 am

OR, iron content is falling, which reduces phytoplankton growth, fewer phytoplankton means fewer clouds.

Ocean primary productivity has been falling most everywhere for as long as we’ve been measuring it. Probably because we killed too many whales. The whales used to move nutrients from deeper waters to shallower by eating deep stuff and excreting near the surface. With far fewer nutrients recyclers, the oceans are becoming deserts.

Industrial whaling kept going until the 1980s. It stopped then because we pretty much ran out of whales.

Jay Willis
June 8, 2020 12:16 pm

They say: “Our study is the first to provide a mechanism for such a wide-spread decline”.

I wrote a paper several years ago that suggested that overfishing might have caused the change in plankton size spectrum, because fish have evolved to maintain their primary food source. I suggested that this was effected through the use of turbulence which has been reported for large schools of shelf fish such as sardines and herring. This paper is actually a great result for my hypothesis – the climate change hypothesis tacked on the end of theirs is least risk familiar rubbish, but the data are the data.

Anyhow, my paper is available, and open source:

Wake sorting, selective predation and biogenic mixing: potential reasons for high turbulence in fish schools.

I’ll be very happy to answer any questions.

Jim Whelan
Reply to  Jay Willis
June 8, 2020 1:31 pm

I think the word, “provide” in the paper is incorrect. The proper word is “speculate”. They re making a guess, not providing the answer.

Cause and effect is difficult in a purely observational science and if this were a real scientific paper it would admit that they are making a guess and provide ways to validate or invalidate the guess. But, they aren’t interested in actually knowing the answer, they only want to prolong the “climate change” scare.

Tom Abbott
June 8, 2020 1:39 pm

From the article: “Our study is the first to provide a mechanism for such a wide-spread decline, and this understanding is essential to project future responses to climate change.”

Sorry, you haven’t even provided a mechansim for Human-caused Climate Change yet (that’s what the author is talking about), so you don’t really have a mechanism for these changes you observe in the ocean, if you are blaming them on the non-existent Human-caused Climate Change claims.

There’s no evidence for Human-caused Climate Change. Don’t base studies on something that has never been shown to exist.

June 8, 2020 9:35 pm

A little off topic, but is anyone else incensed about NOAA’s new global SST anomaly map that shows gray for SSTs that are +-0.2C…

comment image

From the time color-scale SSTs became available, NOAA never used this new gray scale coloring for SST anomalies between +-0.2C…. Why start obfuscating SST data now?

My hypothesis is that huge areas of global oceans are cooling (shifting to blue), which is detrimental to “The Cause”, and to hide this fact, NOAA added this new gray scale to decrease the area of SST anomalies that are turning blue..

The entire CAGW scam is gray… CAGW advocates go out of their way to hide and obfuscate the truth; the truth has no agenda…

June 9, 2020 7:49 am

What’s in your wallet….and effluent?

June 10, 2020 8:37 am

” This study demonstrates a knock-on effect through the food web, and it is only by continuing our monitoring that we will identify multiple stressors acting on our marine environment, and hopefully sustain and protect our productive oceans.”

Blame the Green Turtles for being in denial and unsettling the science of dooming-
Increasing numbers of turtles and baleen whales have no impact on plankton whatsoever and it’s all about two legged landlubbers.

%d bloggers like this:
Verified by MonsterInsights