Sea urchins cope with rising CO2 levels

Apr 09, 2013 by Marcia Malory report
Melissa Pespeni, Stanford University, checks the fertilization rate of urchins on spawning day. Credit: Eric Sanford

(Phys.org) —Increasing levels of carbon dioxide (CO2) in the atmosphere are causing oceans to become more acidic. This situation poses a threat to marine organisms with shells made of calcium carbonate, because acid will corrode these shells. If they are to survive, these organisms will have to adapt to conditions of high acidity. In a paper published in Proceedings of the National Academy of Sciences, Melissa Pepseni of Indiana University at Bloomington and her colleagues at Stanford University and University of California, Davis report that when exposed to high CO2 levels, purple sea urchins (Strongylocentrotus purpuratus) experience significant changes in genes that affect survival in an acidic environment. This indicates that the sea urchins can adapt to high CO2 levels caused by climate change.

Pepseni and her team chose to study sea urchins, which have spines, because these marine animals have very high levels of . The scientists collected adult purple sea urchins from the North American Pacific coast, a region that often experiences upwellings of CO2-rich water; sea urchins from this region may already have a high proportion of alleles associated with survival in high CO2 conditions.

After fertilizing eggs from females with sperm from males, the scientists raised the larvae produced in conditions of either ambient or elevated acidity. Ambient levels corresponded to of 400 parts per million. Elevated levels of 900 ppm matched expected atmospheric CO2 concentrations in the year 2100.

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Sea urchin babies and hamburgers? See how scientists use genetics to understand how sea urchins are able to withstand increasingly acidic ocean water.

Larvae in both groups survived long enough to metamorphose to the next juvenile state. Although the larvae raised in the high acid condition experienced a slight reduction in size, possibly reflecting increased energy costs, this had no affect on their survival rate.

Other than that, there were few visible differences between the two groups. However, showed that the high CO2 group experienced significant changes in genes related to mineral growth, lipid metabolism and ion homeostasis, all of which affect the ability to cope with high acid levels. Genetic variation in the ambient CO2 group was random.

The researchers believe that natural selection in the high CO2 group encouraged the promotion of alleles increasing fitness in an acid environment. While the study reveals that can sometimes adapt to high acid levels, they caution that the ability to adapt successfully in a challenging environment requires genetic diversity. Sea urchins are already extremely diverse genetically and those used in the study could already have inherited a higher proportion of alleles associated with survival in high CO2 conditions. Other organisms may not have these advantages. In addition, stressors such as temperature change and overfishing could reduce population sizes and therefore decrease genetic diversity even further.

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More information: Evolutionary change during experimental ocean acidification, PNAS, Published online before print April 8, 2013, doi: 10.1073/pnas.1220673110

Abstract
Rising atmospheric carbon dioxide (CO2) conditions are driving unprecedented changes in seawater chemistry, resulting in reduced pH and carbonate ion concentrations in the Earth's oceans. This ocean acidification has negative but variable impacts on individual performance in many marine species. However, little is known about the adaptive capacity of species to respond to an acidified ocean, and, as a result, predictions regarding future ecosystem responses remain incomplete. Here we demonstrate that ocean acidification generates striking patterns of genome-wide selection in purple sea urchins (Strongylocentrotus purpuratus) cultured under different CO2 levels. We examined genetic change at 19,493 loci in larvae from seven adult populations cultured under realistic future CO2 levels. Although larval development and morphology showed little response to elevated CO2, we found substantial allelic change in 40 functional classes of proteins involving hundreds of loci. Pronounced genetic changes, including excess amino acid replacements, were detected in all populations and occurred in genes for biomineralization, lipid metabolism, and ion homeostasis—gene classes that build skeletons and interact in pH regulation. Such genetic change represents a neglected and important impact of ocean acidification that may influence populations that show few outward signs of response to acidification. Our results demonstrate the capacity for rapid evolution in the face of ocean acidification and show that standing genetic variation could be a reservoir of resilience to climate change in this coastal upwelling ecosystem. However, effective response to strong natural selection demands large population sizes and may be limited in species impacted by other environmental stressors.

Press release

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User comments : 18

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antigoracle
2.2 / 5 (20) Apr 09, 2013
So, it's an established fact, that as it warms, the oceans release more and more CO2, then how's this deadly acidification supposed to happen. What next acid baths for the Polar Bears?
More and more it's being realized that the only thing not to survive all this CO2 will be the AGW Alarmist.
djr
4.1 / 5 (13) Apr 09, 2013
Wow - I am so glad that all the scientists are wrong. Antigoracle has solved the problem - the ocean PH is not changing - they just need to recalibrate their little PH meter thingys - see - problem solved.
robeph
2.4 / 5 (9) Apr 09, 2013
Come in dir, give him some credit, if you need to double check his sources just call them at 1-900-PSYCHIC it's much cheaper than those silly science journals at only 2.99$ per minute.
Howhot
3.1 / 5 (8) Apr 09, 2013
Well @dir, I guess @antigoracle and @robeph just do not understand the carbon cycle. What dumb asses. The oceans are the largest sink for CO2 and as we pull it out of the ground we are putting it back into the water. I suggest that @robeph call his psychic and ask what the future holds for human kind (and his/her future kids) when it's to hot for life, or to acidic for fish.
gregor1
2.3 / 5 (8) Apr 09, 2013
Could it be that sea urchins are already adapted to higher CO2 levels as they evolved at a time when CO2 was several orders of magnitude than today?
Maggnus
2.8 / 5 (5) Apr 09, 2013
I think he was being sarcastic Howhot. I thought it was funny, considering how bone-chillingly stupid some of the other posters who put comments on the thread are.
djr
4 / 5 (8) Apr 09, 2013
Well @dir, I guess @antigoracle and @robeph just do not understand the carbon cycle. What dumb asses

I am afraid you have me there Howhot - I don't have a really in depth understanding of the carbon cycle - but I really liked antigoracle's explanation - it made me feel so much better - see - don't worry about a thing - the silly scientists didn't realize that the oceans will give up all of the C02 - there is no change in the ocean PH - every thing is good in the world (I will be more specific - this is sarcasm).
Maggnus
3.7 / 5 (6) Apr 09, 2013
(I will be more specific - this is sarcasm).


And well done I might add. I realized in reading that, that my comment may have been misinterpreted. I meant I think robeph was being sarcastic.
Jimee
3.4 / 5 (8) Apr 10, 2013
Current scientific fact is ignored while beliefs long ago discredited are touted as overwhelming evidence for ignoring the crisis that is upon us. If we close our eyes hard enough it won't happen?
djr
3.1 / 5 (7) Apr 10, 2013
Current scientific fact is ignored while beliefs long ago discredited are touted as overwhelming evidence for ignoring the crisis that is upon us. If we close our eyes hard enough it won't happen?

You can't have read the climate gate emails Jimee - they invalidate millions of hours research and data - ask Antigoracle - who will explain you how the world really works. You see - this one scientist (who works for the oil and gas industry - shhhhh.) went before Jim Inhoffe's committee - and reported that a 'prominent scientist' (gosh - just can't remember the name) wrote him an email - declaring that scientists were trying to make the MWP disapear - in order to get billions of dollars in grants - that would otherwise have been spent on Easter candy for the little children - can you believe these awful scientists?
ubavontuba
2.1 / 5 (8) Apr 10, 2013
So an ancient species is adaptable to multiple climates and conditions. Why should this be at all surprising to anyone?
alfie_null
2.2 / 5 (6) Apr 10, 2013
So an ancient species is adaptable to multiple climates and conditions. Why should this be at all surprising to anyone?

If someone is incapable of understanding the situation, we can hardly expect him to be surprised.
antigoracle
1.5 / 5 (8) Apr 10, 2013
It's truly funny to see the AGW Alarmist Cult lurking on this forum, increasing the rank of each others "brilliant" comments. It's their own little peer review, just like the one that got the Hockey Stick Lie, plastered all over the IPCC report.
Howhot
3.4 / 5 (5) Apr 11, 2013
As one of these "AGW Alarmist Cult" lurkers, I certainly do understand how wrong you are on every point that is even slightly related to the subject of global warming. The fact is, there is no lie in the Hockey stick, it is what it is; a measurement, supported by facts that you don't have. You @antigoracle, are just another of these dips that will suck on any conspiratorial tit the pops up on the internet. I guess you join Ubbatubba in that respect.

So have you looked up what the carbon cycle is? Do you understand how the ocean becomes more acidic as excess CO2 is sucked into the massive ocean waters. The amount of CO2 produced is so excessive that it's built up in the atmosphere to point that it's melting the Arctic and Antarctic poles?

Of course not because your a dumb ass just like all of the other deniers of global warming.

So... Your going to lie, twist, and distort AGW just to be a dip. Good luck when science wins and everything horrible proves out.


antigoracle
1.7 / 5 (6) Apr 12, 2013
So have you looked up what the carbon cycle is? Do you understand how the ocean becomes more acidic as excess CO2 is sucked into the massive ocean waters. The amount of CO2 produced is so excessive that it's built up in the atmosphere to point that it's melting the Arctic and Antarctic poles?
-- Howhot
So, read up moron.
Has the Arctic and Antarctic melted in the past?
If so, was it CO2 responsible?
If so, who was responsible for the CO2?

Howhot
3.4 / 5 (5) Apr 12, 2013
Has the Arctic and Antarctic melted in the past? Not in the last 1million years.

If so, was it CO2 responsible? YES

If so, who was responsible for the CO2? What was an Asteroid strike.

Read up some more. You have been brain washed by internet BS.

antigoracle
1.8 / 5 (5) Apr 14, 2013
Has the Arctic and Antarctic melted in the past? Not in the last 1million years.

Really!!
Recent studies in Siberia have established conclusively that trees were present across the entire Russian Arctic, all the way to the northernmost shore, during the warm period that occurred about 8000-9000 years ago, a few thousand years after the end of the last ice age. Remains of frozen trees still in place on these lands provide clear evidence that a warmer arctic climate allowed trees to grow much further north than they are now.

http://www.greenf...ndra.htm
Howhot
4 / 5 (4) Apr 17, 2013
Really!!
Recent studies in Siberia have established conclusively that trees were present across the entire Russian Arctic, all the way to the northernmost shore, during the warm period that occurred about 8000-9000 years ago...


Really? Temperature records indicate the global temps have been pretty steady to with 0,5C/year for an extensive period. Until the 1900's when you see fossil fuel burning causing a very marked increase in CO2 levels and partnered with temp lagging behind.

Atmospheric CO2 levels are now so high, they have surpassed nearly a million years of historical maximums. And it's all man made.

You can call me an AGW alarmist or whatever, but you will eventually have to deal with it, and deal with your denial.