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Ocean acidification: Key concepts from the past

Past environmental change, based on Earth’s natural variability, can inform scientists how humans have influenced climate and the environment on a global scale. One of the most well-publicized facets of human-induced climate change is the release of carbon dioxide into the atmosphere, which has sharply increased since the Industrial Revolution. Only within the last decade have scientists begun to characterize the ecological consequences of increased carbon dioxide absorption by the oceans.

When carbon dioxide from the atmosphere dissolves in the oceans, a number of chemical changes occur and seawater becomes more acidic. This process is called ocean acidification (OA). This shift creates conditions that make it difficult for marine animals with shells (e.g. corals, clams, oysters, and snails) to build their skeletons. While there are many studies that demonstrate the negative effects of ocean acidification on individual species, it is much more difficult, time consuming, and costly to conduct experiments on an entire marine ecosystem scale. However, we can look to the past: the fossil record serves as an ideal natural laboratory for studying large-scale impacts of ocean acidification on ecosystems over time.

Continue reading ‘Ocean acidification: Key concepts from the past’

The hunt for a super coral: can cold-water corals adapt to ocean acidification?

When most people think of a coral reef they are imagining a sunny tropical beach, but many coral species are actually found in the dark, cold waters of the deep sea. These corals, commonly known as cold-water corals due to their preference for low temperatures, form beautiful ecosystems that are teeming with life. One of the largest threats to these slow-growing and fragile ecosystems is ocean acidification, the gradual reduction in the pH of our oceans caused by the excess carbon dioxide humans emit into the atmosphere. By the year 2100, it is expected that over 70% of stony corals in the deep sea will live in waters that are so acidic that they may corrode corals and make it difficult or even impossible for them to form hard skeletons.

In a previous publication scientists from Marine Conservation Institute and Temple University showed that cold-water corals in different ocean basins had completely opposite responses to ocean acidification, suggesting some populations may be much more resilient to climate change. What about individual corals within a population – could they also exhibit different responses? Enter the hunt for a ‘super coral’, corals with a genetic makeup that render them more resilient to ocean acidification. In an increasingly acidic ocean super corals would have higher survival and reproductive rates, and over many generations would comprise an increasingly large portion of the population. If these super corals already exist in the deep sea, there is a chance that cold-water coral populations may be able to adapt quickly enough to survive in the face of climate change.

Continue reading ‘The hunt for a super coral: can cold-water corals adapt to ocean acidification?’

Response of diatoms to ocean acidification

Marine diatoms are important primary producers that thrive in diverse and dynamic environments. Using the model species Thalassiosira pseudonana, we demonstrated in a detailed physiological and transcriptomic survey that approximately 40 percent of the transcriptome varied significantly and recurrently, reflecting large, reproducible cell-state transitions between four principal states: I) “dawn,” following twelve hours of darkness, II) “dusk,” following twelve hours of light, III) exponential growth and nutrient replete, IV) stationary phase and nutrient depleted. Repeated shifts in the transcript levels of hundreds of genes encoding sensory, signaling, and regulatory functions accompanied the four cell-state transitions, provided a preliminary map of the highly coordinated gene regulatory program under varying conditions. These results explain, in comprehensive detail, how the diatom gene regulatory program operates under varying environmental conditions (Ashworth et al. 2013).

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Our efforts paid off! Congress is investing in our ocean this year, but more support needed for 2018 (excerpts)

(…) This week, Congress released a late, but welcome, federal budget for 2017. It is a budget that reflects our ocean values, with investments in agencies like the National Ocean Service and the National Marine Fisheries Service. (…) The National Oceanic and Atmospheric Administration (NOAA) overall faces cuts under the new administration, with specific cuts proposed for Coastal Zone Management, Sea Grant and others.

Drumbeat of support

During the last 15 months, ocean champions ranging from business leaders to surfers and stay-at-home moms called their members of Congress, signed petitions and letters, shared their stories on Facebook and even hopped on flights to D.C. to meet with their senators in person. They talked about the importance of a healthy ocean to their lives and communities, as well as their jobs and their bottom line. (…)

Ocean acidification research will continue at current funding levels, supporting the on-the-water sensors and data that businesses, like shellfish harvesters, need to succeed in the face of changing oceans. (…)

Congress is paying attention, and they have heard from their constituents that cuts to ocean programs simply don’t have public support. (…)

Addie Haughey, Ocean Currents, 4 May 2017. Article.

WITNESS: Investigating ocean acidification (Part 2)

In the second part of his WITNESS blog investigating the dangers of increasing ocean acidification, CONOR PURCELL learns that increase rates are already 10 times higher than at any time in the last 55 million years which, naturally, does not bode well for all ocean ecosystems

The continental shelf rolls out for some hundreds of kilometres west of Ireland’s Galway coast, before the Rockall Trough. Here the seafloor falls sharply off the shelf down to abyssal depths of over 3000 metres. Continentals shelves like this are host to a range of marine ecosystems, including cold water corals; a much less discussed variety compared to their warm water cousins.

According to Dr Tríona McGrath, a marine scientist at the National University of Ireland Galway, and funded by Ireland’s Marine Institute : “The Rockall Trough hosts an array of cold water coral ecosystems, interacting with a range of water masses along the Irish continental margin, Rockall Bank and Porcupine Bank. These deep water reef structures support a rich biodiversity and are particularly vulnerable in a more acidic ocean.”

Continue reading ‘WITNESS: Investigating ocean acidification (Part 2)’

WITNESS: Investigating ocean acidification (Part 1)

In the first of his two-part WITNESS blog CONOR PURCELL joins the Irish marine scientists aboard the Celtic Explorer to learn more about how they are testing for ocean acidification

As carbon dioxide levels in our atmosphere continue to increase, more and more of the gas is drawn down into the world’s oceans, causing the pH of water to lower. This means our oceans are acidifying; and as the 21st century rolls on, these changes are expected to have consequences for marine ecosystems, as well as the services they provide, such as fisheries.

It is these ocean changes which a team at Ireland’s Marine Institute have been tasked with measuring working aboard the Celtic Explorer research vessel, some 400km from Galway, from where we departed last month.

Looking over the vessel’s edge we can see the CTD  – an acronym for Conductivity, Temperature, Depth – unit reflecting sunlight from below the sea’s surface. From here on deck, within the surrounding darker shades of sea the unit appears as a submerged circle of blue light. Then, as the scientists wait in anticipation, it is raised from the water and pulled aboard.

Continue reading ‘WITNESS: Investigating ocean acidification (Part 1)’

An important new step for understanding how ocean acidification will affect marine ecosystems

In this new Analysis article published by a team of Chilean and European colleagues, we provides a new approach to reconcile apparent contradicting results on the impact of ocean acidification on marine organisms.

Ocean acidification is the global warming evil twin. It is another consequence of human carbon dioxide (CO2) emissions. A quarter of the CO2 we have emitted to the atmosphere is captured by the ocean and significantly modifying its chemistry, including a decrease in the seawater pH. Since the industrial revolution, the oceanic pH has dropped from 8.2 to 8.1, which does not seem like much, but if we even consider that the pH scale is logarithmic, this apparently small change means that the ocean is becoming 30% more acidic. Further, recent studies suggest that acidification rate could accelerate from now to the end of the century, resulting in a potentially catastrophic impact on marine ecosystems. Understanding the impact of ocean acidification is now a priority and one of the targets of then UN Sustainable Development Goals for 2030.

During the last years, the scientific community has been really active, and scientists have been conducting many ocean acidification experiments, where a variety of marine species are usually exposed to pH or CO2 levels expected for the near future. Through this experimental approach, it has been achieved an unequivocal consensus that if we keep emitting CO2 at the same rate, ocean acidification will significantly impact marine species, ecosystems and services that we are depending on. However, they struggle with apparently contradicting results.

Continue reading ‘An important new step for understanding how ocean acidification will affect marine ecosystems’


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Ocean acidification in the IPCC AR5 WG II

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