Acidic oceans threaten fish
Ocean acidification — caused by climate change — looks likely to damage crucial fish stocks. Two studies published today in Nature Climate Change reveal that high carbon dioxide concentrations can cause death1 and organ damage2 in very young fish.
The work challenges the belief that fish, unlike organisms with shells or exoskeletons made of calcium carbonate, will be safe as marine CO2 levels rise.
Oceans act like carbon sponges, drawing CO2 from the atmosphere into the water. As the CO2 mixes with the water, it forms carbonic acid, making the water more acidic. The drop in pH removes calcite and aragonite — carbonate minerals essential for skeleton and shell formation — from the marine environment.
This can mean that corals, algae, shellfish and molluscs have difficulty forming skeletons and shells or that their shells become pitted and dissolve.
At present, atmospheric CO2 levels exceed 380 parts per million and are expected to climb throughout the century to approximately 800 p.p.m. if emissions are not kept in check. And the oceans are expected to continue to sop up the gas, dropping ocean pH by 0.4 units to about 7.7 by 21002.
However, many scientists have suggested that acidification wouldn't be problematic for marine fish because they don’t have exoskeletons and because as adults they possess mechanisms that allow them to tolerate high concentrations of CO2.
But a handful of studies have shown that increased CO2 levels can wreck the sense of smell of orange clown fish larvae and increase the size of the otolith — a bony organ akin to the human inner ear — in white sea bass larvae.
Christopher Gobler, a marine biologist at Stony Brook University in New York, decided to test the effects of rising CO2 levels on the growth and survival of Menidia beryllina, a common schooling fish found in estuaries along the North American coast. He and his colleagues placed the fish embryos into CO2 concentrations comparable to current levels in the seas (about 400 p.p.m.), those expected by mid-century (about 600 p.p.m.) and at levels projected for the end of the century (about 1,000 p.p.m.)1.
“Right away, we saw results,” says Gobler. “Survival rates were cut in half or worse with high concentrations of CO2.” When CO2 concentrations reached 1,000 p.p.m., one-week survival rates dropped by 74%.
The other study2, led by Andrea Frommel, a fisheries biologist at the Leibniz-Institute of Marine Sciences in Kiel, Germany, looked at the effects of acidification on the larvae of Atlantic cod (Gadus morhua) over a two-and-a-half month period. The team reared the fish larvae under three conditions: present day ( about 380 p.p.m.), year 2200 (about 1,800 p.p.m.) and an extreme coastal upwelling scenario (about 4,200 p.p.m), where winds bring large amount of CO2-rich deep water to the surface. As CO2 levels increased, the cod larvae fared less well, developing severe damage to their liver, pancreas, kidney, eye and gut about a month after hatching.
“We’ve always said fish are such good acid–base regulators that they won’t be affected by increasing ocean acidification. But what we found was that the larvae, which haven’t developed these mechanisms yet, are more vulnerable to CO2 than we thought,” says Frommel. The organ damage was serious enough that it could have lowered the cod’s chance of survival, she said.
“These two studies are part of a growing trend that realizes that the broader effects of ocean acidification are much more than just calcification,” says Donald Potts, a coral-reef biologist at the University of California, Santa Cruz.
“If the effects found in these two studies can be generalized to other species of fish, the implications could be very big,” says William Cheung, a marine ecologist at the University of British Columbia’s Fisheries Centre in Vancouver, Canada.
Baumann, H., Talmage, S. C. & Gobler, C. J. Nature Clim. Change http://dx.doi.org/10.1038/nclimate1291 (2011).
Frommel, A. Y. et al. Nature Clim. Change http://dx.doi.org/10.1038/nclimate1324 (2011).
Citation(2011). Acidic oceans threaten fish. Retrieved from http://www.wavesofchange.org/view/news/51cbf2677896bb431f6a925a
Ocean Acidification is now irreversible... at least on timescales of at least... TENS of THOUSANDS of years... Even with stabilisation of atmospheric CO2 at 450 ppm, Ocean Acidification will have profound impacts (death and extinction) on many marine systems. LARGE and rapid reductions of global CO2 emissions are needed globally by at LEAST 50% by 2050. Analysis of past events in Earth's geologic history suggests that chemical recovery (normal pH for LIFE in the Ocean) will take TENS of THOUSANDS of years - while the recovery of ecosystem function and biological diversity (LIFE AS WE KNOW IT) can take much longer. (MILLIONS OF YEARS) http://interacademies.net/10878/13951.aspx --- ..:: "Every day, 70 MILLION TONS of CO2 are released into Earth's atmosphere. ( remaining in the atmosphere for thousands of years ) ..:: "Every day, 20 MILLION TONS of that CO2 are absorbed into the OCEANS, thereby increasing the overall ACIDITY of the OCEANS. By 2100, Ocean acidity will increase another 150 to 200 hundred percent. This is a dramatic change in the acidity of the oceans. And it has a serious impact on our ocean ecosystems; in particular, it has an impact on any species of calcifying organism that produces a calcium carbonate SHELL. - http://www.ClimateWatch.NOAA.gov/video/2010/origin-impacts-ocean-acidification --- ..:: "These are changes that are occurring far too fast for the oceans to correct naturally, said Dr Richard Feely with the US National Oceanic and Atmospheric Administration (NOAA) ..:: "Fifty-five million years ago when we had an event like this (and that took over 10,000 years to occur), it took the oceans over 125,000 years to recover, just to get the chemistry back to normal," he told BBC News. ..:: "It took two to 10 million years for the organisms to re-evolve, to get back into a normal situation. ..:: "So what we do over the next 100 years will have implications for ocean ecosystems from tens of thousands to millions of years. That's the implication of what we're doing to the oceans right now." -- http://www.bbc.co.uk/news/science-environment-17088154 - http://ecodelmar.org/phytoplankton - Calling all "Ocean Defenders", to INFORM the UN-informed "voting" American public of the danger of atmospheric CO2 produced by fossil fuel combustion... leading to global warming and Ocean Acidification... leading to the extinction of the base of the food chain in the Ocean and the loss of oxygen producing phytoplankton that is essential for Life on Earth... the only known planet with Life, as we know it, in the entire universe. Keep saying it to everyone... until everyone is saying it to you. http://EcoDelMar.org/phytoplankton Until a critical mass of American "voters" can actually understand the OA problem, and stop living in denial, there will be no "political will" to solve the problem... mainly caused by Americans and the US military, ( http://EcoDelMar.org/Green_Military ) ... while believing their "might is right"... and believing in the infallibility of the human ego, while ignoring their own Spiritual appreciation/gratitude for Life itself... in effect, worshiping golden idols over Life. While a critical mass of American "voters" stubbornly cling to a blatant denial of the findings of 98% of the top scientists of all time... the problem will not be seen by the "voters"... until it is too late. http://EcoDelMar.org/MBA_blindness ~ Capt LL http://EcoDelMar.org/ -