Ocean acidification

Ocean acidification is often thought of as a future impact of our changing climate. But exactly what is it, what are its impacts and is it really a problem of the future?

As reported in the CSIRO and Bureau of Meteorology’s latest State of the Climate report, oceans around Australia are acidifying 10 times faster than at any point in the last 300 million years. When coupled with ocean warming and deoxygenation, this is putting considerable pressure on our marine environments. Recent research from CSIRO and AIMS has highlighted the changing conditions on the Great Barrier Reef. Drawing on over a decade of observations collected as part of Australia’s Integrated Marine Observing System (IMOS) the team found that the Reef’s rich carbonate seafloor is not buffering against ocean acidification, a process that might offset ocean acidification.

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The future is now for the Great Barrier Reef

New research published by the Australian Institute of Marine Science (AIMS) and CSIRO has shown that ocean acidification is no longer a thing of climate projections, but a present-day reality.

The Great Barrier Reef is the world’s largest coral reef, supporting an enormously biodiverse community of organisms. It provides a multitude of ecosystem functions and services, both biotic and abiotic, benefitting the species of the marine ecosystem and the human population surrounding it. The effect of climate change on coral reefs has been widely studied, and multiple detrimental stressors identified. The extreme extent of recent coral bleaching events, additional stress posed by ocean acidification and other anthropogenic drivers make it hard to see a bright future for the GBR. Nevertheless, the discovery of restoration techniques such as microfragmentation and 3D reef printing give some hope to the conservation of the GBR and the ecosystem services it provides.

Article Highlights

· New modelling technology demonstrates that the level of atmospheric CO2 concentrations are nearing a critical point for the Great Barrier Reefs survival

· The extent of recent coral bleaching on the Great Barrier Reef is considerably more severe than bleaching events of the past

· The synergistic effect of warming oceans and increasing ocean acidity on coral are compounding at an alarmingly high rate

· The recent discovery of microfragmentation gives some hope for restoring thermally tolerant reefs

· 3D printing technology opens new doors to creating structurally complex artificial reefs and maintaining the ecosystem services they provide

Seawater carbonate chemistry has been altered by dramatic increases in anthropogenic CO₂ release and global temperatures, leading to significant changes in rocky shore habitats and the metabolism of most marine organisms. There has been recent interest in how these anthropogenic stresses affect crustose coralline algae (CCA) communities because CCA photosynthesis and calcification are directly influenced by seawater carbonate chemistry. CCA is a foundation species in temperate macroalgal communities, where species succession and rocky shore community structure are particularly susceptible to anthropogenic disturbance. In particular, the disappearance of turf and foliose macroalgae caused by climate change and herbivore pressure results in the dominance of CCA (Figure 1a).

Indigenous people have depended on Olympic Coast marine species for their livelihoods, food security and cultural practices for thousands of years. Today, these species—and the tribal communities that depend on them—are at risk from ocean acidification. Washington Sea Grant, in partnership with the Olympic Coast Treaty Tribes, federal and academic scientists and coastal managers, is working to understand and plan for the impacts of ocean change to tribal community well-being.

Reviewing: Peijnenburg, K. et al. The origin and diversification of pteropods predate past perturbations in the Earth’s carbon cycle. 1–9 (2020). DOI: https://doi.org/10.1073/pnas.1920918117

It’s a bird… It’s a plane… Its a pteropod!

Have you ever heard of a flying snail? Meet the pteropod (with a silent “p”), or “wing footed” sea snail. These snails are considered pelagic meaning they spend their entire life inhabiting the open water rather of creeping along the seafloor. Pteropods and other zooplankton, such as krill, copepods and larvae, serve as a major food source for larger open-water fauna, like fish and whales. Over evolutionary timescales, these snails have thinned, or entirely lost, their shells to become lighter and morphed their foot into two wings for graceful swimming. Those without shells are called gynosomes, or sea angels, and the shelled varieties are referred to as sea butterflies.

With climate change, excess CO₂ dissolves into the ocean resulting in the water becoming more acidic. Molecules in the ocean, like calcium carbonate (which the sea butterflies use to build their shells), naturally buffer, or stabilize, the ocean’s pH (a measure of acidity) by chemically reacting with the CO₂ molecules. However, human-derived levels of CO₂ are so high that there is a significantly lower availability of these buffering molecules for animals who rely on them.

Continue reading ‘A shell of a ride: Pteropod survival through past mass extinction events and insights into present climate change’

These are the findings from nearly forty years of shipboard observations made in the deep Sargasso Sea offshore of the verdant island and surrounding coral reefs of Bermuda.

Fortuitously situated in the middle of the North Atlantic Ocean subtropical gyre, in the Sargasso Sea, scientific discoveries in this region began more than one hundred and twenty years ago with the founding of the Bermuda Biological Station for Research, now known as the Bermuda Institute of Ocean Sciences (BIOS).

After the end of Second World War, Hank Stommel, a pioneering oceanographer from Woods Hole Oceanographic Institution in Cape Cod, thought Bermuda would make an excellent place from which to mount sustained observations of the deep sea at a site called Hydrostation ‘S’, located approximately 25 km southeast of the island. His quote “If Bermuda did not exist, oceanographers would have invented it!” remains just as relevant today as when he first wrote it. Out in the seemingly infinite sea, far from the sight of land and in the realm of flying fishes, clumps of floating Sargassum weed, and home to pelagic seabirds such as the petrel Cahow––thought extinct for most of the nineteenth century––these observations continue to the present day.

Continue reading ‘The Sargasso Sea has become warmer and saltier, and the loss of oxygen and ocean acidification is accelerating’

A few years ago, I experienced the same predicament as any other kid in my 8th grade science class: What on Earth should I choose as the topic of my science fair project? While researching ideas for an experiment, I came across an interesting one. Its ingredients? Sea shells, vinegar, water, and salt. You can probably guess what it entailed…putting the seashells into DIY sea water, then adding vinegar to see what would happen (spoiler: the seashells dissolve).

While I doubt anyone’s dumping vinegar into the sea, we’re certainly doing something similar – on a MUCH larger scale. Yep, this week’s article will be discussing ocean acidification.

Continue reading ‘Ocean acidification: a [pH]ishy dilemma’

Natural ecosystems exist in a delicate balance of biotic and abiotic factors, intertwined through billions of years of evolutionary progression and reliance on each other. As global climate change continues to escalate and impact a myriad of aspects of the natural world, this has never been more important to understand — that the impacts of one action, be it drilling or greenhouse gas emissions or overharvesting, can cascade through the biosphere for centuries to come. One of the more serious side effects of climate change is ocean acidification, which will change our oceans forever if action is not taken — and soon.

Ocean acidification occurs when carbon dioxide (CO2) is absorbed by the ocean from the atmosphere. Since the industrial revolution, humans have emitted 40 billion metric tons of CO2 into the atmosphere, of which 30% has been absorbed by the world’s oceans. When CO2 dissolves into water it creates mild carbonic acid which in turn lowers the pH of the water.  Bivalves, such as oysters and clams, are most at risk from acidification as the acidic water prevents them from building their calcium carbonate shells. Not only are bivalves valuable seafood for commercial and indigenous harvest in the Arctic, but they are also prey for a variety of marine animals, including, but not limited to: fish, walruses, seals and certain species of seabirds. Bears living along the coast have also been observed foraging for clams. Ocean acidification doesn’t only pose a threat to these shell building invertebrates, but to everything above them on the food chain.

Continue reading ‘Acidification and the Arctic Ocean’