Archives de catégorie : biology+acidification

‘Glimmer Of Hope’ For Great Barrier Reef As Study Shows Tolerance To Climate Change

by Nick Visser, December 10, 2018 in Huffpost


Last year’s oceanic heat wave wasn’t as destructive as one the year before, scientists said.

The Great Barrier Reef fared better during an oceanic heat wave last year than during sizzling weather a year earlier that caused hundreds of miles of corals to bleach, according to a study published Monday that suggests the massive structure may be growing more tolerant to climate change.

The report in the journal Nature Climate Change analyzed how corals along the Great Barrier fared in back-to-back mass bleaching events. The reef ― a UNESCO World Heritage Site and the largest living structure on the planet ― was cooked by overheated seawater in 2016 and again in 2017, with images of sickly white coral horrifying people around the globe.

See also here

A Brachiopod’s Twelve-Decade Response to Ocean Acidification and Warming

by Cross et al., November 29, 2018 in CO2Science


Paper Reviewed
Cross, E.L., Harper, E.M. and Peck, L.S. 2018. A 120-year record of resilience to environmental change in brachiopods. Global Change Biology 24: 2262-2271.

In light of all their findings, Cross et al. conclude that “these rhynchonelliform brachiopods have therefore been unaffected in their abilities to construct and maintain their extensive skeletons by the change in ocean acidity and temperature over the last 120 years.” And this is a noteworthy conclusion, given that C. inconspicua is one of the most calcium-carbonate-dependent species globally, and is therefore presumed to be highly susceptible to ocean acidification. It would thus appear that proper incorporation of species’ adaptation and/or acclimation potentials is essential if scientists are to get predictions of the impacts of ocean acidification on marine life correct.

Thriving reef fisheries continue to provide food despite coral bleaching

by Lancaster University, November 29, 2018 in ScienceDaily/Nature


The unexpected results of a 20-year study into reef fisheries published in the journal Nature Ecology and Evolution this week showed fisheries being maintained despite extreme coral bleaching. Remarkably, rapid proliferation of fishes with low dependence on corals led to catches remaining stable or even increasing.

But the results also showed fishing success was ‘patchy’ and more dependent on fewer species.

Around six million people fish on coral reefs. Each year their catch — estimated to be between 1.4 and 4.2 million tonnes — provides a critical source of food and income for many millions more.

Oxygen could have been available to life as early as 3.5 billion years ago

by Imperial College, November 27, 2018 in ScienceDaily


The levels of oxygen dramatically rose in the atmosphere around 2.4 billion years ago, but why it happened then has been debated. Some scientists think that 2.4 billion years ago is when organisms called cyanobacteria first evolved, which could perform oxygen-producing (oxygenic) photosynthesis.

Other scientist think that cyanobacteria evolved long before 2.4 billion years ago but something prevented oxygen from accumulating in the air.

Cyanobacteria perform a relatively sophisticated form of oxygenic photosynthesis — the same type of photosynthesis that all plants do today. It has therefore been suggested that simpler forms of oxygenic photosynthesis could have existed earlier, before cyanobacteria, leading to low levels of oxygen being available to life.

Now, a research team led by Imperial College London have found that oxygenic photosynthesis arose at least one billion years before cyanobacteria evolved. Their results, published in the journal Geobiology, show that oxygenic photosynthesis could have evolved very early in Earth’s 4.5-billion-year history.

See also here

Coral Adaptation and Epigenetics

by Rud Itsvan, November 17, 2018 in WUWT


WUWT has posted several excellent articles by Jim Steele on how global warming alarmism uses corals as the poster child for warming and acidifying oceans, none of which is scientifically justified. A brief review follows, calling attention to a recently discovered additional adaptation mechanism not covered AFAIK by Jim Steele’s posts. The motivation for this post was triggered by a recent lunch with newish neighbor Charles the Moderator (CtM), and his sharing many wonderful underwater photographs of the coral reef he now dives frequently off Pompano Beach (same reef system as off Fort Lauderdale, just a few miles further north and more conveniently onshore).

Proof that Corals are Adapting to Warming Temperatures

by Coles et al., November, 11,  2018 in CO2Science


In light of the above findings, Coles et al. state the obvious, that the corals “were able to withstand elevated temperatures (31.4 °C) for a longer period of time in the current 2017 experiment” compared to the 1970 study. Consequently, they conclude that their results “indicate a shift in the temperature threshold tolerance of these corals to a 31-day exposure to 31.4 °C,” which findings “provide the first evidence of coral acclimatization or adaptation to increasing ocean temperatures.” And that observational reality should hold great bearing on the status and health of coral reefs in response to future climate change. If temperatures rise in the future, clearly, as living organisms, corals can (and do!) adapt. Alarmist predictions of their fast and ensuing demise due to global warming should not be taken too seriously.

Holocene temperature in the Iberian Peninsula reconstructed studying insect subfossils

by University of Barcelona, November 9, 2018 in ScienceDaily


Regional differences regarding other reconstructions

The results of the study show a temperature rise in the beginning of the Holocene, reaching the highest values in the Holocene Climate Optimum (about 7,800 years ago). There are also high temperatures until about 6,000 years ago, when a decline of temperature started and led to the lowest values in the first stage of the late Holocene (about 4,200 and 2,000 years ago).

Last, researchers detected a rise of temperatures over the two last millenniums, but they state they have to be careful with these data. “We cannot guarantee the observed rise in the reconstruction results from a temperature rise only, we cannot rule out other variables that can influence at other levels, such as the gradual increase of the anthropic activity in the area, which can change the community of Chironomidae to species that adapt to higher temperatures, but there are also human influence indicators,” says Narcís Prat.

Although these conclusions can coincide with other paleoclimate reconstructions, results also highlight some divergences at a regional level. “These differences can occur due the fact that some indicators point out to different seasonal signs. Therefore, Chironomidae are indicators of temperature in summer, while others such as chrysophites or alkenones are related to winter/spring temperatures,” notes the researcher.

A tool to evaluate climate trends

Biodiversité, le vrai, le faux et l’incertain

by Prof. Paul Berth, 4 novembre 2018 in ScienceClimatEnergie


Le 30 octobre 2018 sortait le dernier rapport du WWF[1] concernant l’état de la biodiversité (voir ici). Les données obtenues sont très préoccupantes. De nombreux médias ont bien entendu présenté ce rapport de façon très alarmiste en exagérant certains points. Le but du présent article est de remettre les pendules à l’heure, en démêlant le vrai du faux et en présentant certaines incertitudes.

1. Que dit exactement le rapport du WWF? Le rapport du WWF nous dit que globalement, entre 1970 et 2014, l’index LPI (Living Planet Index) a chuté de 60% (Figure 1). Il n’est pas question ici de mettre en doute les résultats obtenus par le WWF mais simplement de les mettre en perspective. L’index LPI est calculé en tenant compte du nombre d’individus pour plusieurs espèces. Au total, ce sont 4 005 espèces qui ont été considérées, réparties en 16 704 populations (il peut donc y avoir plusieurs populations pour une même espèce). Ces populations proviennent de tous les continents. Pour toutes les espèces prises en compte le nombre d’individus a été estimé, puis des sommes ont été établies.

Large stretches of coral reefs can be rehabilitated

by University of California – Davis, September 27, 2018 in ScienceDaily


For the study, published this week in the journal Restoration Ecology, researchers installed 11,000 small, hexagonal structures called “spiders” across 5 acres of reef in the center of Indonesia’s Coral Triangle. Coral diversity is the highest on Earth in that region but is threatened by human activity, including overfishing, pollution and climate change.

Between 2013 and 2015, researchers attached coral fragments to the structures, which also stabilized rubble and allowed for water to flow through freely.

A CORAL SUCCESS STORY

Live coral cover on the structures increased from less than 10 percent to more than 60 percent. This was more than what was reported for reefs in many other areas of the Coral Triangle, at a cost of about $25 per square meter.

Les coraux blanchissent depuis très longtemps

by Prof. Dr. Paul Berth, 5  septembre 2018, in ScienceClimatEnergie


Le blanchissement des coraux est un phénomène dont on entend souvent parler dans les médias. Il s’agirait d’un grave problème environnemental, dont la fréquence augmente, et qui pourrait mener à la perte totale des récifs coralliens. Le réchauffement climatique global, qui serait causé par l’augmentation de la concentration atmosphérique en CO2 est, bien entendu, pointé du doigt. Cependant, le blanchissement des coraux n’est-il pas un phénomène très ancien? Est-il seulement causé par des variations de température? Quel recul avons-nous à ce sujet? Une récente publication de Nicholas Kamenos et Sebastian Hennige, deux chercheurs anglais des Universités de Glasgow et d’Édimbourg, apporte de nouveaux éléments.

Remember when they told us coral bleaching was a sure result of recent man-made global warming? Never mind.

by Anthony Watts, August 17, 2018 in WUWT


From the “science eventually self-corrects” department, new science showing coral bleaching of the Great Barrier Reef is a centuries-old problem, well before “climate change” became a buzzword and rising CO2 levels were blamed.

Marc Hendrickx writes:

New paper shows coral bleaching in GBR extending back 400+ years.

Glacier depth affects plankton blooms off Greenland

by Helmholtz Centre for Ocean Research Kiel (GEOMAR), Auhsut 14, 2018 in ScienceDaily


The unusual timing of highly-productive summer plankton blooms off Greenland indicates a connection between increasing amounts of meltwater and nutrients in these coastal waters. Researchers now show that this connection exists, but is much more complex than widely supposed. Whether increasing meltwater has a positive or negative effect on summertime phytoplankton depends on the depth at which a glacier sits in the ocean.

“So, the study shows that further melting of Greenland’s glaciers only leads to stronger summer plankton blooms under very specific conditions, an effect that will ultimately end with very extensive further melting,” Hopwood summarizes the results of the study.

Ice sheets of the last ice age seeded the ocean with essential nutrient silica

by University of Bristol, August 10, 2018 in ScienceDaily


Silica is needed by a group of marine algae (the microscopic plants of the oceans) called diatoms, who use it to build their glassy cell walls (known as frustules).

These plankton take up globally significant amounts of carbon — they remove carbon dioxide from the atmosphere via photosynthesis, and act as a natural carbon sink when they die and fall to the bottom of the ocean — and form the base of the marine food chain.

The researchers are also planning to use more complex and realistic computer models to delve deeper into the potential changes in the global silica cycle since the last glacial maximum. These might include more accurate representations of ocean currents, recycling of silica in the water column, and potential changes to the marine algal community.

New Study Shows Some Corals Might Adapt to Climate Changes

by Anthony Watts, August 4, 2018 in WUWT


UM Rosenstiel School-led study exposes two threatened corals to future climate change conditions

MIAMI—New research shows that not all corals respond the same to changes in climate. The University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science-led study looked at the sensitivity of two types of corals found in Florida and the Caribbean and found that one of them—mountainous star coral—possesses an adaptation that allows it to survive under high temperatures and acidity conditions.

“Stressful periods of high temperature and increasingly acidic conditions are becoming more frequent and longer lasting in Florida waters,” said Chris Langdon, marine biology and ecology professor and lead author on the new study. “However, we found that not all coral species are equally sensitive to climate change and there’s hope that some species that seemed doomed may yet develop adaptations that will allow them to survive as well.”

See also (in French) here and  here

In the ocean’s twilight zone, tiny organisms may have giant effect on Earth’s carbon cycle

by Florida State University, July 18, 2018 in ScienceDaily


Deep in the ocean’s twilight zone, swarms of ravenous single-celled organisms may be altering Earth’s carbon cycle in ways scientists never expected, according to a new study from Florida State University researchers.

In the area 100 to 1,000 meters below the ocean’s surface — dubbed the twilight zone because of its largely impenetrable darkness — scientists found that tiny organisms called phaeodarians are consuming sinking, carbon-rich particles before they settle on the seabed, where they would otherwise be stored and sequestered from the atmosphere for millennia.

This discovery, researchers suggest, could indicate the need for a re-evaluation of how carbon circulates throughout the ocean, and a new appraisal of the role these microorganisms might play in Earth’s shifting climate.

The findings were published in the journal Limnology and Oceanography.