Ocean acidification

The first documented discovery of “extreme corals” in mangrove lagoons around Australia’s Great Barrier Reef is yielding important information about how corals deal with environmental stress, scientists say. Thirty four species of coral were found to be regularly exposed to extreme low pH, low oxygen and highly variable temperature conditions making two mangrove lagoons on the Woody Isles and Howick Island potential “hot-spots” of coral resilience.

Although coral cover was typically low and somewhat patchy in the lagoon waters, DECRA Research Fellow Dr Emma Camp, from the University of Technology Sydney (UTS) said the discovery was important because it “provides novel information on the mechanisms that support coral resilience to stressors such as climate change and pollution.”

Continue reading ‘Extreme mangrove corals found on the Great Barrier Reef’

Diatoms’ silica cell walls help drag the tiny carbon-bearing algae down into the ocean when they die. But acidifying oceans can lead to thinner walls. M.I. WALKER/SCIENCE SOURCE

Ocean acidification doesn’t just erode calcium carbonate shells. It can also slow the rate at which tiny algae called diatoms build their beautiful, intricate silica cell walls. Thinner walls mean lighter diatoms — making the algae less able to transport carbon to the deep ocean, scientists report August 26 in Nature Climate Change.

Vast diatom blooms act as a biological pump in the ocean, adding oxygen to the atmosphere and drawing carbon dioxide out of it. To protect themselves from predators, diatoms also build houses of glass — strong cell walls of silica. When diatoms die, the walls act as ballast, causing the creatures to sink and sequester carbon from the atmosphere.

Continue reading ‘Ocean acidification could weaken diatoms’ glass houses’

The oceans are warming and acidifying at an accelerating rate, but other adverse changes are also under way because of climate change. Several of these other changes, including ones to ocean microbes that regulate Earth’s carbon and oxygen cycles, will increasingly have their impacts felt in coming decades, say the authors of a new study.

The scientists, who work at Princeton University in the United States, examined physical and chemical changes taking place in the oceans as a result of a rise in atmospheric CO2 fueled by our emissions. They then applied diagnostical tools to map the emergence of anthropogenic impacts on various timescales. “We found emergence timescales that ranged from less than a decade to more than a century, a consequence of the time lag between the chemical and radiative impacts of rising atmospheric CO2 on the ocean,” they write.

Continue reading ‘Our effects on the oceans have yet to make themselves truly felt’

Sea temperature and ocean acidification have climbed during the last three decades to levels beyond what is expected due to natural variation alone, a new study led by Princeton researchers finds. Meanwhile other impacts from climate change, such as changes in the activity of ocean microbes that regulate the Earth’s carbon and oxygen cycles, will take several more decades to a century to appear. The report was published Aug. 19 online in the journal Nature Climate Change.

The study looked at physical and chemical changes to the ocean that are associated with rising atmospheric carbon dioxide due to human activities. “We sought to address a key scientific question: When, why and how will important changes become detectable above the normal variations that we expect to see in the global ocean?” said Sarah Schlunegger, a postdoctoral research associate at Princeton University’s Program in Atmospheric and Oceanic Sciences (AOS).

Continue reading ‘Roadmap for detecting changes in ocean due to climate change’

Jose Quezada — For the Times-Standard

A four-year academic study funded by California Sea Grant and conducted by lead researcher Ted Grosholz of UC Davis found that oyster habitats in bays and estuaries along the California coast can be impacted by climate change.

The study, conducted from 2014-17, was performed in Tomales Bay and the research found that the greatest impact on oysters occurred in the earliest stages of development, particularly when the oyster was ready to start forming its shell.

Increased ocean temperatures, increased runoff from rivers and the inflow of upwelled ocean waters all combine to affect the growth of oysters, according to the study.

“To my current knowledge, the CO2 accumulation in the water and the atmosphere lower the pH and increase the acidity, and in that higher acidic water it’s difficult for larval shellfish to form a shell,” said Todd Van Herpe of Humboldt Bay Oyster Company, which operates oyster beds on the bay.

Continue reading ‘UC Davis study shows effects of climate change on oyster farming’

Corals fascinate amateurs and experts alike: small polyps that extract calcium carbonate from seawater and use it to build their elaborate skeletons. But climate change, with rising water temperatures and increasing ocean acidification, is changing the living conditions of corals at an unprecedented rate. Whether they can keep pace with these changes and adapt is an open question. Now researchers from the GEOMAR Helmholtz Centre for Ocean Research Kiel and the University of California are providing new insights with a study published today in international journal Nature Communications. For this study, which was co-financed by the Austrian Science Fund FWF (Fonds zur Förderung der wissenschaftlichen Forschung) and the US NSF, the scientists investigated the response of the stony corals Porites astreoides to low pH and high dissolved carbon content in their natural environment.

Continue reading ‘Stony corals: limits of adaption’