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By Jo Nova
Cold is the Catastrophe
A hotter world might not be so horrible. Back in the early Holocene, 10,000 years ago, rivers flowed in the middle of the Sahara desert, and they were filled with fish. The photo above is what remains of Takarkori Lake today. If only climate change could bring back the fish?
While we were distracted in 2020, researchers published a paper about an trove of bones and body parts they had dug out of a cave in Southwest Libya, which is roughly the middle of the Sahara today. Surprisingly they found 17,551 bones, and even more surprisingly, 80% of them were from fish.
The people who dined there were catching tilapia and clariid catfish, and sometimes the odd mud turtle, mollusc and a crocodile or two. The lake (pictured above) is about 6 kilometers from the cave (below), and all the bones appear to be human refuse. It’s kind of the ultimate archaeological FOGO dump.
Somehow, this restaurant that stayed open for 6,000 years left behind layer after layer of undisturbed dining history. Gradually, over thousands of years the diners ate less fish, and more beef, goat and mutton.
Amazingly, 17,000 bits of […]
Just when you think headlines can’t be that stupid:
Baby fish may not find their way home as the level of CO2 in the ocean rises, study finds
— ABC Isabel Dayman
Baby fish may lose their ability to find their way home in the future due to rising CO2 levels in the ocean, a marine ecology expert has found.
What the study found was that fish larvae were not paying attention to the right noises.
The researchers put the larvae in a tank and bubbled CO2 through it constantly. They appear to forget that CO2 changes naturally every night on reefs all over the world. Fish are not just used to having a daily shift, they prefer it.
In shallow water, ocean acidification happens at 7pm daily, and after 400 million years, somehow, fish have adapted.
One previous study declared fish might become reckless in a high CO2 world, but later discovered that it was the laboratory setting that was the problem, not the CO2. When they added the daily pH swing back to their tanks, the fish behaved better and coped with the extra CO2. The real message is that laboratories […]
In 1964 an earthquake made some parts of the Pacific into ponds on a few islands. Fifty years later and the fish in those ponds are now freshwater fish. Apparently the genes for dealing with that sort of wild extreme change are held by some of the fish in the crowd and natural selection can work its wonders in a decade.
In terms of ocean acidification, this is as catastrophic as it gets, not only did the ocean become “more acidic” but it stopped being an ocean.
It can’t get much worse than this for a fish, and yet somehow life on Earth had the answer.
What’s the pH of those ponds — The ocean pH is 8.1, rain is 5.5. Those ponds will be somewhere in between.
And some people think a man-made “ocean acidication” that’s smaller than this and slower, will devastate the ocean.
Science Daily
Evolution is usually thought of as occurring over long time periods, but it also can happen quickly. Consider a tiny fish whose transformation after the 1964 Alaskan earthquake was uncovered by University of Oregon scientists and their University of Alaska collaborators.
The fish, […]
It’s a disaster for fish and chip shops. Children won’t know what a sea-food restaurant is.
Our oceans are warming by 0.005 °C per year (if you believe a thermometer system with a 0.5 °C error). But fish that cope with five degrees of natural variation will apparently be devastated by an average rise of five thousands of a degree per year. Who knew?
Earth’s oceans vary from 0 – 30° C. Warm and cold currents wander, eddy currents swirl. Very little of the ocean’s surface is actually at the exact “average” temperature. In any one spot, temperatures can be a full five degrees above or below average (as in this NOAA graph, below).
The sea surface temperature varies by up to five degrees from average every day
Humans may well be changing global fish stocks, but why toss in the unscientific advertising for “climate change”? As for the acidification scare, ocean pH changes on a daily basis, and hundreds of studies show that marine life might even benefit from a slight increase in “acidification”.
ScienceDaily
Seafood supply altered by climate change
The global supply of seafood is set to change substantially and many people will not […]
You will never guess, but salmon that survived the hot Holocene period, and the even hotter Eemian, will probably be OK in a slightly warmer world. Expert researchers found this surprising.
Given the broad spread of Salmon in the Northern Hemisphere, and their past survival through every single interglacial warm period of the Pleistocene, I would have thought that they could cope with quite a bit of climate change. As it turns out, they cope so well, that even salmon eggs that come from a 12C environment can be raised in an environment a whopping 8C warmer, and they were not noticeably any worse off.
Part of the concern with salmon was the spawning and eggs, and the problem with getting the salmon to shift their maternity wards and childcare arrangements (which they seem very attached too). But presumably those breeding grounds have varied before in temperature, and salmon didn’t die out, so — at least with this problem — nature has it figured out.
Map: Salmon and Climate Change, Fish in hot water, Red List.
Atlantic salmon also show capacity to adapt to warmer waters
Populations of Atlantic salmon have a surprisingly good capacity to adjust […]
Filed under: Light relief (for a moment til we get back to The solar model)
Not only will your air conditioner make little fish more reckless, but other fish might seriously not be able to find their friends for coffee. I did not make up that headline. Your taxes did.
Note the carefully phrased results:
“Whilst fish kept under normal conditions consistently chose the familiar school, fish reared under high CO2 conditions showed no preference for either the unfamiliar or familiar school.”
If increasing CO2 was a politically-correct achievement, would that same result carry a headline telling us that “Climate Change makes Fish More Confident with Strangers”?
9.3 out of 10 based on 72 ratings […]
AIMS researchers found that fish near a natural CO2 vent were not as scared of predators as their colleagues from more alkaline water: “Ocean Acidification robs reef fish of their fear of predators”.
They compared populations in reefs with normal pH levels with those near the vent. I note this line in the abstract didn’t make it to the press release:
“Contrary to expectations, fish diversity and community structure differed little between CO2 seeps and nearby control reefs.”
So the natural laboratory of the vent has biodiversity and a community, despite the “acid” (which is not acidic of course). Milne Bay, I gather, has pH of 7.7.
The abstract points out that there might be a reason why fish are bolder:
“Our results suggest that recruitment of juvenile fish from outside the seeps, along with fewer predators within the seeps, is currently sufficient to offset any negative effects of high CO2 within the seeps.”
Less predators, anyone?
So these might be well adapted little fish that suit the natural environment around them? Call the press…
If warming were politically correct, then people might say the fish became more confident. : -)
Indeed shouldn’t we worry that fish in higher […]
Experiments with Zebra Fish show that if their embryo’s develop in warmer water, they not only are able to swim faster but they cope better in both warmer and colder water. (How catastrophic can that be, I ask you?)
ScienceDaily (Aug. 14, 2012) — New research by McMaster University biologist Graham Scott suggests that growing up at warmer temperatures helps some aquatic animals cope with climate change, raising questions about the limits of adaptation.
Scott and Johnston found that when embryos raised in warm water experienced temperature variation as adults, they could swim faster, their muscle was better suited for aerobic exercise, and they expressed at higher levels many of the genes that contribute to exercise performance.
The improvements were true for the adult fish in warmer and colder water alike — a finding that surprised the researchers.
“We thought that they might do better under warmer conditions because they grew up in warmer conditions. We didn’t think they’d also do better under colder conditions, but they did.
Their research shows the fish are hardier after being raised in a warm-water nursery, and raises the question of how far the […]
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JoNova A science presenter, writer, speaker & former TV host; author of The Skeptic's Handbook (over 200,000 copies distributed & available in 15 languages).
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