Ocean acidification

Changes in ocean chemistry and temperature have had a dramatic effect on the diversity of corals and sea anemones, according to a team of scientists who have traced their evolution through deep time. A new study, published Aug. 31 in the journal Nature Ecology and Evolution, finds that reef-building corals emerged only when ocean conditions supported the construction of these creatures’ stony skeletons, whereas diverse softer corals and sea anemones flourished at other times. Without a significant change to anthropogenic carbon emissions, the new findings present stark implications for the present and future of hard-bodied corals while suggesting a silver lining for the diversity of some of their softer-bodied relatives.

Continue reading ‘Warmer, acidifying ocean brings extinction for reef-building corals, renewal for relatives’

The scaffolds that help hold together the world’s tropical reefs are at risk from acidification due to increased carbon dioxide in the world’s oceans, according to geoscientists at the University of Sydney.

Extensive sampling of the Great Barrier Reef fossil record has shown that the calcified scaffolds that help stabilize and bind its structure become thin and weaker as pH levels fall.

Scientists have seen incidental evidence for this in the past, but a new study led by Zsanett Szilagyi of the Geocoastal Research Group at the University of Sydney has shown that this is a global process, affecting reefs worldwide.

The research is published this week in Marine Geology.

Continue reading ‘Great Barrier Reef ‘glue’ at risk from ocean acidification’

The Arctic Ocean will take up more CO2 over the 21st century than predicted by most climate models. This additional CO2 causes a distinctly stronger ocean acidification. These results were published in a study by climate scientists from the University of Bern and École normale supérieure in Paris. Ocean acidification threatens the life of calcifying organisms – such as mussels and “sea butterflies” – and can have serious consequences for the entire food chain.

The ocean takes up large amounts of man-made CO2 from the atmosphere. This additional CO2 causes ocean acidification, a process that can already be observed today. Ocean acidification particularly impacts organisms that form calcium carbonate skeletons and shells, such as molluscs, sea urchins, starfish and corals. The Arctic Ocean is where acidification is expected to be greatest.

Continue reading ‘Arctic Ocean acidification worse than previously expected’

Ocean acidification is changing the productivity and composition of phytoplankton communities at the base of the aquatic food web. Now a study shows that acidification impairs the swimming ability of flagellated microalgae, suggesting that their capacity to survive is threatened in a high CO₂ world.

Scientists gather around a Conductivity, Temperature, Depth (CTD) rosette, a machine used during the West Coast Ocean Acidification Cruise, to collect samples that measure concentrations of oxygen, pH, and carbon, salinity, chlorophyll and nutrients.

One of the earth’s biggest allies in the fight against global warming is the world’s oceans. Since the industrial revolution, the burning of fossil fuels has caused carbon dioxide, the dominant greenhouse gas, to be released into the atmosphere. Approximately 25% of that carbon dioxide is taken each year from the atmosphere by the world’s oceans — without which, the earth’s atmosphere would have a higher greenhouse gas concentration and temperature.

While pulling the anthropogenic, or man-made, carbon dioxide from the atmosphere is good for the earth’s system, it leads to problems for the world’s oceans as dissolved carbon dioxide becomes carbonic acid and leads to ocean acidification, changing the chemistry of the world’s oceans and impacting some of the life forms within it. In particular, the organisms that use calcium to build their carbonate skeletons — such as corals or mollusks — will have a harder time under acidified conditions.

Continue reading ‘Measuring climate change’

A juvenile glass sponge in the lab displaying tissue loss (bottom) and living tissue (top). Credit: Angela Stevenson, UBC

Warming ocean temperatures and acidification drastically reduce the skeletal strength and filter-feeding capacity of glass sponges, according to new UBC research.

The findings, published in Scientific Reports, indicate that ongoing climate change could have serious, irreversible impacts on the sprawling glass sponge reefs of the Pacific Northwest and their associated marine life—the only known reefs of their kind in the world.

Ranging from the Alaska-Canada border and down through the Strait of Georgia, the reefs play an essential role in water quality by filtering microbes and cycling nutrients through food chains. They also provide critical habitat for many fish and invertebrates, including rockfish, spot prawns, herring, halibut and sharks.

Continue reading ‘Climate change an imminent threat to glass sponge reefs’

A team of fisheries scientists and marine policy experts, led by a University of Rhode Island researcher, examined how climate change is affecting the ocean environment and found that the changing conditions will likely result in increased fisheries-related conflicts and create new challenges in the management of global fish stocks.

The team’s research was recently published in the journal Marine Policy.

Elizabeth Mendenhall, URI assistant professor of marine affairs, said that ocean warming, acidification, and sea-level rise that are a direct result of climate change are causing populations of fish to shift, making fish increasingly scarce, shifting the boundaries of where nations can legally fish, and increasing the intensity of fishing pressure around the world. The result will be growing conflicts between individual fishermen, fishing communities, fishing nations, and fishery managers, according to the team’s research.

On February 8, 2016, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured several images of blooming phytoplankton and swirling currents along the coast of California and western Mexico. The images were stitched together into a composite built with data from the red, green, and blue wavelength bands on VIIRS, along with chlorophyll data. A series of image-processing steps highlighted the color differences and subtle features in the water.
CREDIT: NASA image by Norman Kuring, NASA’s Ocean Color Web.

CU Boulder researchers have developed a method that could enable scientists to accurately forecast ocean acidity up to five years in advance. This would enable fisheries and communities that depend on seafood negatively affected by ocean acidification to adapt to changing conditions in real time, improving economic and food security in the next few decades.

Previous studies have shown the ability to predict ocean acidity a few months out, but this is the first study to prove it is possible to predict variability in ocean acidity multiple years in advance. The new method, described in Nature Communications, offers potential to forecast the acceleration or slowdown of ocean acidification.

“We’ve taken a climate model and run it like you would have a weather forecast, essentially – and the model included ocean chemistry, which is extremely novel,” said Riley Brady, lead author of the study, and a doctoral candidate in the Department of Atmospheric and Oceanic Sciences.

Continue reading ‘Ocean acidification prediction now possible years in advance’

Stony Brook University’s Christopher J. Gobler, Endowed Chair of Coastal Ecology and Conservation, and Stephen J. Tomasetti, Science Teaching and Research to Inform Decisions (STRIDE) fellow, consider accumulating scientific evidence on the harmful effects of coastal hypoxia (low oxygen) and acidification (decreasing pH, increasing acidity) in coastal ecosystems in the April 24 issue of the journal Science.

In a Policy Forum, Dissolved oxygen and pH criteria leave fisheries at risk, the scientists suggest approaches that would address current policy shortfalls and facilitate improved protection of aquatic life.

Continue reading ‘Researchers: dissolved oxygen and pH policy leave fisheries at risk’