a news stream provided by the Ocean Acidification International Coordination Center (OA-ICC)
Carina Bunse has written a thesis on marine bacteria and how they respond to the changes in their environment. Bacteria affect nutrient turnover in the Baltic Sea and with it the balance of the sea. As they are invisible, our knowledge of marine bacteria is still limited. By studying these microbes and their genes, we can learn more about how the ocean will behave in the future.
Continue reading ‘The balance of marine bacteria in the Baltic Sea’
Ocean uptake of CO2 slows the rate of anthropogenic climate change but comes at the cost of ocean acidification. Observations now show that the seasonal cycle of CO2 in the ocean also changes, leading to earlier occurrence of detrimental conditions for ocean biota.
The increase of atmospheric CO2 (ref. 1) has been predicted to impact the seasonal cycle of inorganic carbon in the global ocean2,3, yet the observational evidence to verify this prediction has been missing. Here, using an observation-based product of the oceanic partial pressure of CO2 (pCO2) covering the past 34 years, we find that the winter-to-summer difference of the pCO2 has increased on average by 2.2 ± 0.4 μatm per decade from 1982 to 2015 poleward of 10° latitude. This is largely in agreement with the trend expected from thermodynamic considerations. Most of the increase stems from the seasonality of the drivers acting on an increasing oceanic pCO2 caused by the uptake of anthropogenic CO2 from the atmosphere. In the high latitudes, the concurrent ocean-acidification-induced changes in the buffer capacity of the ocean enhance this effect. This strengthening of the seasonal winter-to-summer difference pushes the global ocean towards critical thresholds earlier, inducing stress to ocean ecosystems and fisheries4. Our study provides observational evidence for this strengthening seasonal difference in the oceanic carbon cycle on a global scale, illustrating the inevitable consequences of anthropogenic CO2 emissions.
Continue reading ‘Strengthening seasonal marine CO2 variations due to increasing atmospheric CO2’
Woods Hole Oceanographic Institution scientists Anne Cohen (left) and Nathan Mollica extract core samples from a giant Porites coral in Risong Bay, Palau. They are co-authors of a new study in the Proceedings of the National Academy of Sciences showing how increasing ocean acidifcation will affect coral skeleton growth. Credit: Richard Brooks, Lightning Strike Media Productions, Palau
The rising acidity of the oceans threatens coral reefs by making it harder for corals to build their skeletons. A new study identifies the details of how ocean acidification affects coral skeletons, allowing scientists to predict more precisely where corals will be more vulnerable.
Corals grow their skeletons upward toward sunlight and also thicken them to reinforce them.
The new research, led by scientists at Woods Hole Oceanographic Institution (WHOI), shows that ocean acidification particularly impedes the thickening process—decreasing the skeletons’ density and leaving them more vulnerable to breaking. The study was published today in the Proceedings of the National Academy of Sciences.
Continue reading ‘Scientists pinpoint how ocean acidification weakens coral skeletons’
Significance
Ocean acidification (OA) threatens coral reef futures by reducing the concentration of carbonate ions that corals need to construct their skeletons. However, quantitative predictions of reef futures under OA are confounded by mixed responses of corals to OA in experiments and field observations. We modeled the skeletal growth of a dominant reef-building coral, Porites, as a function of seawater chemistry and validated the model against observational data. We show that OA directly and negatively affects one component of the two-step growth process (density) but not the other (linear extension). Combining our growth model with Global Climate Model output, we show that skeletal density of Porites corals could decline by up to 20.3% over the 21st century solely due to OA.
Abstract
Ocean acidification (OA) is considered an important threat to coral reef ecosystems, because it reduces the availability of carbonate ions that reef-building corals need to produce their skeletons. However, while theory predicts that coral calcification rates decline as carbonate ion concentrations decrease, this prediction is not consistently borne out in laboratory manipulation experiments or in studies of corals inhabiting naturally low-pH reefs today. The skeletal growth of corals consists of two distinct processes: extension (upward growth) and densification (lateral thickening). Here, we show that skeletal density is directly sensitive to changes in seawater carbonate ion concentration and thus, to OA, whereas extension is not. We present a numerical model of Porites skeletal growth that links skeletal density with the external seawater environment via its influence on the chemistry of coral calcifying fluid. We validate the model using existing coral skeletal datasets from six Porites species collected across five reef sites and use this framework to project the impact of 21st century OA on Porites skeletal density across the global tropics. Our model predicts that OA alone will drive up to 20.3 ± 5.4% decline in the skeletal density of reef-building Porites corals.
Continue reading ‘Ocean acidification affects coral growth by reducing skeletal density’
A new, high-tech traveler is catching a ride on Alaska’s largest passenger ferry. At the end of October, the Columbia, which can carry up to 500 travelers, set off on its two week, nearly 2,000-mile course from Bellingham, Washington to Skagway, Alaska. But for the first time, an onboard system is measuring temperature and levels of salt, oxygen, and carbon dioxide in the seawater every three minutes, giving scientists a detailed look at how climate change could impact the northern Pacific coast.
The main focus of this experiment, which researchers hope will run for at least five years, is ocean acidification. Scientists want to know where acidification is already happening and predict which areas will be at risk in the future. The project is the latest collaborative effort to understand whether ocean acidification, a by-product of climate change, could affect Alaska’s unique coastal ecosystems and, ultimately, its young aquaculture industry. Alaskan officials like Governor Bill Walker hope shellfish and kelp farming can be an area of future economic growth for the state, according to Samuel Rabung, aquaculture section chief at the Alaska Department of Fish and Game in the Division of Commercial Fisheries. But successful aquatic farming depends on healthy marine ecosystems.
Continue reading ‘Alaskans take to the seas to fight climate change’
The impacts of climate change aren’t a distant threat for the Pacific shellfish industry. Acidifying seawater is already causing problems for oyster farms along the West Coast and it’s only expected to get worse.
That has one Bay Area oyster farm looking for ways to adapt by teaming up with scientists, who are studying how the local ecosystem could lend a helping hand.
Continue reading ‘The lowly seagrass that could save your oysters from climate change’
Scientists have proposed that marine organisms living in regions with large daily or seasonal swings in environmental conditions should more easily acclimate to slow changes over decades such as those caused by climate change. But that optimism might not hold if such short-term variability were also affected. Indeed, a new study published in the journal Nature Climate Change finds that if atmospheric CO2 continues to increase, the differences in extremes in surface-ocean acidity between summer and winter will roughly double by the end of the century.
Continue reading ‘Growing seasonal extremes in ocean acidity’
How ocean acidification will affect marine organisms depends on changes in both the long-term mean and the short-term temporal variability of carbonate chemistry1,2,3,4,5,6,7,8. Although the decadal-to-centennial response to atmospheric CO2 and climate change is constrained by observations and models1, 9, little is known about corresponding changes in seasonality10,11,12, particularly for pH. Here we assess the latter by analysing nine earth system models (ESMs) forced with a business-as-usual emissions scenario13. During the twenty-first century, the seasonal cycle of surface-ocean pH was attenuated by 16 ± 7%, on average, whereas that for hydrogen ion concentration [H+] was amplified by 81 ± 16%. Simultaneously, the seasonal amplitude of the aragonite saturation state (Ωarag) was attenuated except in the subtropics, where it was amplified. These contrasting changes derive from regionally varying sensitivities of these variables to atmospheric CO2 and climate change and to diverging trends in seasonal extremes in the primary controlling variables (temperature, dissolved inorganic carbon and alkalinity). Projected seasonality changes will tend to exacerbate the impacts of increasing [H+] on marine organisms during the summer and ameliorate the impacts during the winter, although the opposite holds in the high latitudes. Similarly, over most of the ocean, impacts from declining Ωarag are likely to be intensified during the summer and dampened during the winter.
Ocean acidification may interfere with the calcifying physiology of marine bivalves. Therefore, understanding their capacity for acclimation and adaption to low pH over multiple generations is crucial to make predictions about the fate of this economically and ecologically important fauna in an acidifying ocean. Transgenerational exposure to an acidification scenario projected by the end of the century (i.e., pH 7.7) has been shown to confer resilience to juvenile offspring of the Manila clam, Ruditapes philippinarum. However, whether, and to what extent, this resilience can persist into adulthood are unknown and the mechanisms driving transgenerational acclimation remain poorly understood. The present study takes observations of Manila clam juveniles further into the adult stage and observes similar transgenerational responses. Under acidified conditions, clams originating from parents reproductively exposed to the same level of low pH show a significantly faster shell growth rate, a higher condition index and a lower standard metabolic rate than those without prior history of transgenerational acclimation. Further analyses of stable carbon isotopic signatures in dissolved inorganic carbon of seawater, individual soft tissues and shells reveal that up to 61% of shell carbonate comes from metabolic carbon, suggesting that transgenerationally acclimated clams may preferentially extract internal metabolic carbon rather than transport external seawater inorganic carbon to build shells, the latter known to be energetically expensive. While a large metabolic carbon contribution (45%) is seen in non-acclimated clams, a significant reduction in the rate of shell growth indicates it might occur at the expense of other calcification-relevant processes. It therefore seems plausible that, following transgenerational acclimation, R. philippinarum can implement a less costly and more efficient energy-utilizing strategy to mitigate the impact of seawater acidification. Collectively, our findings indicate that marine bivalves are more resilient to ocean acidification projected for the end of the century than previously thought.
Summer Graduate Course at Friday Harbor Laboratories (College of the Environment, University of Washington), July 16 – August 17, 2018
Instructors: Drs. Jon Havenhand (Dept. of Marine Sciences, University of Gothenburg, Sweden), Andrew Dickson (Scripps Institution of Oceanography, UC San Diego), Terrie Klinger (School of Marine & Environmental Affairs, University of Washington)
This graduate level course introduces students to the theory, methods, and techniques needed to conduct successful experiments on the biological effects of ocean acidification. Through a combination of lectures, laboratory exercises, and field work we will prepare students to perform ocean acidification research at their home institutions and in other settings.
Continue reading ‘Research methods in ocean acidification (course)’
A new study of tiny marine snails called sea butterflies shows the great lengths these animals go to repair damage caused by ocean acidification. The paper, led by researchers at British Antarctic Survey, is published this month in the journal Nature Communications.
The ocean absorbs around one quarter of the carbon dioxide (CO2) emitted into the atmosphere and this CO2 reacts with seawater, causing the pH to fall, a phenomenon called ocean acidification. It has been feared this acidification is detrimental to certain organisms as corrosive waters could dissolve their shells or skeletons. Sea butterflies, also known as pteropods (Limacina helicina), are mm-scale animals that are prevalent in the polar regions. They have evolved ‘wings’ instead of a foot, enabling them to swim through the ocean. Their delicate shells are made from aragonite, the least stable form of calcium carbonate, and are so thin they are completely translucent.
Continue reading ‘Sea butterflies repair shell damage from ocean acidification’
The Paleocene–Eocene Thermal Maximum (PETM, 56 Ma) was a phase of rapid global warming associated with massive carbon input into the ocean–atmosphere system from a 13C-depleted reservoir. Many midlatitude and high-latitude sections have been studied and document changes in salinity, hydrology and sedimentation, deoxygenation, biotic overturning, and migrations, but detailed records from tropical regions are lacking. Here, we study the PETM at Ocean Drilling Program (ODP) Site 959 in the equatorial Atlantic using a range of organic and inorganic proxies and couple these with dinoflagellate cyst (dinocyst) assemblage analysis. The PETM at Site 959 was previously found to be marked by a ∼ 3.8 ‰ negative carbon isotope excursion (CIE) and a ∼ 4 °C surface ocean warming from the uppermost Paleocene to peak PETM, of which ∼ 1 °C occurs before the onset of the CIE. We record upper Paleocene dinocyst assemblages that are similar to PETM assemblages as found in extratropical regions, confirming poleward migrations of ecosystems during the PETM. The early stages of the PETM are marked by a typical acme of the tropical genus Apectodinium, which reaches abundances of up to 95 %. Subsequently, dinocyst abundances diminish greatly, as do carbonate and pyritized silicate microfossils. The combined paleoenvironmental information from Site 959 and a close-by shelf site in Nigeria implies the general absence of eukaryotic surface-dwelling microplankton during peak PETM warmth in the eastern equatorial Atlantic, most likely caused by heat stress. We hypothesize, based on a literature survey, that heat stress might have reduced calcification in more tropical regions, potentially contributing to reduced deep sea carbonate accumulation rates, and, by buffering acidification, also to biological carbonate compensation of the injected carbon during the PETM. Crucially, abundant organic benthic foraminiferal linings imply sustained export production, likely driven by prokaryotes. In sharp contrast, the recovery of the CIE yields rapid (≪ 10 kyr) fluctuations in the abundance of several dinocyst groups, suggesting extreme ecosystem and environmental variability.
Global warming’ is in the news almost daily these days, but rarely do we hear about its ‘evil twin’ or ‘the other carbon dioxide (CO2) problem’, viz. ocean acidification. Global warming, caused mainly by anthropogenic CO2 emissions, is apparently accompanied by ocean acidification, which is another major growing global problem with continued increase in atmospheric CO2 levels. While there is large uncertainty in the detection and attribution of climate warming because of the large natural variability in surface temperatures, ocean acidification is relatively a certain and straight forward consequence ofrising atmospheric CO2.
Is ocean acidification a serious threat to marine life? Why is so little attention paid to this other CO2 problem? What is the present level of understanding of this problem? Has ocean acidification already manifested at least in some parts of the global oceans? What are its likely consequences? Is life on this planet headed toward extinction because of ocean acidification? What can we do to prevent ocean acidification?
Continue reading ‘Is ocean acidification from rising carbon dioxide a grave threat?’
The Department of Oceanography and Coastal Studies at Louisiana State University, Baton Rouge invites PhD and Masters applicants to join the Marine Geochemistry group on a number of recently funded projects to understand the fate, transformation and transport of carbon in estuarine and shelf sediments of coastal Louisiana and their impact on water quality. The successful candidates will have a Bachelors or Masters degree in marine science, geology, chemistry or other related field, and excellent written and oral communication skills. The successful candidate will be expected to participate in field work in Louisiana wetland and offshore Gulf of Mexico.
Continue reading ‘PhD and MS Research Assistantships in carbon cycle and ocean acidification’
Scientists and NOAA Hollings scholars at the Northeast Fisheries Science Center (NEFSC) are studying how Atlantic silverside, one of the most common fishes on the Atlantic Coast and an important diet component of many larger fishes of this region, are impacted by changes in ocean acidification (increased CO2, lower pH), increased temperature, and lower dissolved oxygen projected to occur in the future.
Molokai students are working on some groundbreaking science projects, from an app that helps repel deer and other unwanted animal intruders from your yard, to inventing a device that could play a huge role in the future of ocean science. Students at Molokai Middle and High schools and Aka`ula showcased their science projects last week at the Science Fair Family Night, as winners from school-wide competitions are preparing to move on to the Maui Regional Science and Engineering Fair next month. Hosted by Molokai LIVE and UPLINK programs, the event celebrated students’ application of science to real-world projects.
Acid Horizon follows marine ecologist Dr. Erik Cordes on a harrowing deep-sea expedition to track down the “supercoral,” a strain of the deep-water coral Lophelia pertusa that seems to possess the unique genetic capability to thrive in a low-pH ocean. The film will make its World Premiere at the 2018 Santa Barbara International Film Festival.
The film’s protagonist Dr. Cordes, Associate Professor and Vice Chair of Biology at Temple University, explains: “Our research has shown that some coral colonies – the “Supercorals” – do better than the rest when challenged by ocean acidification. This film delivers that message through an intimate story and an epic adventure. It is essential that this story is told so that people are aware of this hidden threat, but also understand that there is hope and still time to take action.”
