Life on the edge: Is ocean acidification a threat to deep-sea life? (text & video)

Even animals living in the deep ocean are affected by the increasing emissions of carbon dioxide into the atmosphere. The ocean naturally absorbs carbon dioxide from the atmosphere, resulting in a more acidic habitat for ocean life. Researchers at the Monterey Bay Aquarium Research Institute use a series of specially designed chambers to study how deep-sea animals will respond to this change in ocean chemistry. They also bring animals into the laboratory, where the animals can be observed as they are exposed to seawater resembling current and future carbon-dioxide levels. It is important to understand how deep-sea animals will respond to impending changes in ocean chemistry because a disturbance to one part of an ecosystem can have cascading effects throughout the entire ecosystem.

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As CO2 acidifies the oceans, scientists develop a new way to measure its effect on marine ecosystems

Following a 5,000 km long ocean survey, research published in the Proceedings of the National Academy of Sciences presents a new way to measure how the acidification of water is affecting marine ecosystems over an entire oceanic basin.

As a result of man-made emissions, the content of CO2 in the atmosphere and oceans has increased dramatically during recent decades. In the ocean, the accumulating CO2 is gradually acidifying the surface waters, making it harder for shelled organisms like corals and certain open sea plankton to build their calcium carbonate skeletons.

Since this process impacts the functioning of many marine ecosystems, it has been intensively studied in recent years. However, getting an accurate measure is complicated because the effect of ocean acidification on the rates of calcium produced by marine organisms is highly variable and species specific. Since scientists tend to use local and site-specific field measurements, treating reef environments and open sea environments separately, their measurements reflect the local response of individual organisms to elevated CO2 levels, and not the overall picture.

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Basin-scale estimates of pelagic and coral reef calcification in the Red Sea and Western Indian Ocean

Basin-scale calcification rates are highly important in assessments of the global oceanic carbon cycle. Traditionally, such estimates were based on rates of sedimentation measured with sediment traps or in deep sea cores. Here we estimated CaCO3 precipitation rates in the surface water of the Red Sea from total alkalinity depletion along their axial flow using the water flux in the straits of Bab el Mandeb. The relative contribution of coral reefs and open sea plankton were calculated by fitting a Rayleigh distillation model to the increase in the strontium to calcium ratio. We estimate the net amount of CaCO3 precipitated in the Red Sea to be 7.3 ± 0.4·1010 kg·y−1 of which 80 ± 5% is by pelagic calcareous plankton and 20 ± 5% is by the flourishing coastal coral reefs. This estimate for pelagic calcification rate is up to 40% higher than published sedimentary CaCO3 accumulation rates for the region. The calcification rate of the Gulf of Aden was estimated by the Rayleigh model to be ∼1/2 of the Red Sea, and in the northwestern Indian Ocean, it was smaller than our detection limit. The results of this study suggest that variations of major ions on a basin scale may potentially help in assessing long-term effects of ocean acidification on carbonate deposition by marine organisms.

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NOAA, partners provide real-time ocean acidification data to Pacific coast shellfish growers

New portal builds on NOAA’s commitment to provide public access to data from observational network.

Shellfish farms and hatcheries along the Pacific U.S. coast  can now get real-time, online ocean acidification data through the Integrated Ocean Observation System (IOOS), a NOAA-led national-regional partnership working to provide new tools and forecasts to improve safety, enhance the economy, and protect the environment. The data, ranging from carbon dioxide concentrations to salinity and water temperatures can be found through the IOOS Pacific Region Ocean Acidification Data Portal which began operations this month.

“This new portal provides critical environmental intelligence to researchers, coastal managers, and end users such as shellfish aquaculture farms,” said Libby Jewett, Ph.D., director of NOAA’s Ocean Acidification Program. “We hope that the data gathered through this system, combined with on-going research, can help NOAA and our partners provide information to support effective adaptation strategies and other coastal resource decision making.”

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40 years of scratching reveals ocean acidification data

As carbon dioxide levels increase due largely to human emissions, the world’s oceans are becoming highly corrosive to a number of organisms that call it home. But the rate of acidification and related changes are anything but uniform. That’s why a new study aims to set a baseline for nearly every patch of saltwater from sea to acidifying sea so that future acidification and its impacts can be better monitored.

Taro Takahashi, a geochemist at Lamont-Doherty Earth Observatory who authored the new study in Marine Chemistry, said it has been a decades-long process to compile enough data about ocean acidification to effectively set a benchmark.

Think of the ocean as a giant scratch ticket and the ships and research stations in Bermuda, Hawaii, Iceland and elsewhere as a coin used to slowly scratch away at the surface, revealing just how much the ticket is worth. It took 40 years of scratching but now there’s finally enough data in Takahashi’s eyes to set an accurate baseline.

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Quantifying the relative importance of transcellular and paracellular ion transports to coral polyp calcification

Ocean acidification due to rising atmospheric pCO2 slows down coral calcification and impedes reef formation, with deleterious consequences for the diversity of reef ecosystems. Such effects contrast with the capacity of corals to actively regulate the chemical composition of the calcifying fluid where calcification occurs. This regulation involves the active transport of calcium, bicarbonate, and hydrogen ions through epithelium cells, the transcellular pathway. Ions can also passively diffuse through intercellular spaces via the paracellular pathway, which directly exposes the calcifying fluid to changes in ocean chemistry. Although evidence exists for both pathways, their relative contribution to coral calcification remains unknown. Here we use a mathematical model to test the plausibility of different calcification mechanisms also in relation to ocean acidification. We find that the paracellular pathway generates an efflux of calcium and carbonate from the calcifying fluid, causing a leakage of ions that counteracts the concentration gradients maintained by the transcellular pathway. Increasing ocean acidity exacerbates this carbonate leakage and reduces the ability of corals to accrete calcium carbonate.

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Ocean acidification crumbling the shells of the sea

Photo by C. Vonderhaar

Photo by C. Vonderhaar

If there is one thing we know from the history of life on Earth, it is that the oceans are resilient and relentless. Nearly four billion years ago the first raindrops fell from our cooling planet, accumulating in low basins and forming the first oceans. It is from these oceans that the first forms of life emerged and then continued to grow, expand and evolve. Over four billion years, they endured centuries of change, differing compositions of gaseous atmospheres, and yet they still held the capacity to support the evolution of life – a process that created the most complex and conscious being to stand upright and walk this planet: the oceans gave rise to us.

Just as life has changed in the past, the planet continues to change today. Yet there is vastly marked difference. No longer is the ocean changing on a scale of geological time – tens of millions of years; the ocean is changing at a rate faster than it has ever seen. This has a singularly human cause: our rapid increase in carbon dioxide emissions. These rising levels of carbon dioxide alter not only the temperature of the planet, shifting our climate in ways that scientists call climate change, but also the chemistry of the ocean in a process known as ocean acidification.

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