Archives par mot-clé : Organisms

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.

Scientists discover Earth’s youngest banded iron formation in western China

by University of Alberta, July 11, 2018 in ScienceDaily

Discovery provides evidence of iron-rich seawater much later than previously thought.

The banded iron formation, located in western China, has been conclusively dated as Cambrian in age. Approximately 527 million years old, this formation is young by comparison to the majority of discoveries to date. The deposition of banded iron formations, which began approximately 3.8 billion years ago, had long been thought to terminate before the beginning of the Cambrian Period at 540 million years ago.

The Early Cambrian is known for the rise of animals, so the level of oxygen in seawater should have been closer to near modern levels. “This is important as the availability of oxygen has long been thought to be a handbrake on the evolution of complex life, and one that should have been alleviated by the Early Cambrian,” says Leslie Robbins, a PhD candidate in Konhauser’s lab and a co-author on the paper.

Why life on Earth first got big

by University of Cambridge, June 25, 2018 in ScienceDaily

Some of the earliest complex organisms on Earth — possibly some of the earliest animals to exist — got big not to compete for food, but to spread their offspring as far as possible.

The research, led by the University of Cambridge, found that the most successful organisms living in the oceans more than half a billion years ago were the ones that were able to ‘throw’ their offspring the farthest, thereby colonising their surroundings. The results are reported in the journal Nature Ecology and Evolution.

Prior to the Ediacaran period, between 635 and 541 million years ago, life forms were microscopic in size, but during the Ediacaran, large, complex organisms first appeared, some of which — such as a type of organism known as rangeomorphs — grew as tall as two metres.


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Ancient Greenland was much warmer than previously thought

by Amanda Morris, June 4, 2018 inNorthwesternUniversity

A tiny clue found in ancient sediment has unlocked big secrets about Greenland’s past and future climate.

Just beyond the northwest edge of the vast Greenland Ice Sheet, Northwestern University researchers have discovered lake mud that beat tough odds by surviving the last ice age. The mud, and remains of common flies nestled within it, record two interglacial periods in northwest Greenland. Although researchers have long known these two periods — the early Holocene and Last Interglacial — experienced warming in the Arctic due to changes in the Earth’s orbit, the mix of fly species preserved from these times shows that Greenland was even warmer than previously thought.

Giant clams tell the story of past typhoons

by Hokkaido University, May 24, 2018 in ScienceDaily

A highly precise method to determine past typhoon occurrences from giant clam shells has been developed, with the hope of using this method to predict future cyclone activity.

A team of researchers led by Tsuyoshi Watanabe of Hokkaido University has discovered that giant clams record short-term environmental changes, such as those caused by typhoons, in their shells. Analyzing the shell’s microstructure and chemical composition could reveal data about typhoons that occurred before written records were available… (…)

The whole Tridacna maxima valve. The shell was cut in two sections along the maximum growth axis.
Credit: Komagoe T. et al., Journal of Geophysical Research: Biogeosciences, April 19, 2018

The gypsum gravity chute: A phytoplankton-elevator to the ocean floor


Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, May 22, 2018 in ScienceDaily

When marine algae die, they usually float in slow motion to the ocean’s depths. However, during an expedition with the research icebreaker Polarstern to the Arctic in the spring of 2015, scientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) discovered a phenomenon that significantly accelerate this transport: tiny gypsum crystals, which form during the freezing of salt in the porous spaces of Arctic sea ice, weigh down the phytoplankton like heavy ballast, pulling them to the bottom within a matter of hours. The effect is like an express elevator for the carbon they contain. “This mechanism was previously completely unknown,” says marine bio-geologist Dr Jutta Wollenburg … (…)

Tiny fossils unlock clues to Earth’s climate half a billion years ago

by University of Leicester, May 9, 2018 in ScienceDaily

The research, published in Science Advances, suggests that early animals diversified within a climate similar to that in which the dinosaurs lived.

This interval in time is known for the ‘Cambrian explosion’, the time during which representatives of most of the major animal groups first appear in the fossil record. These include the first animals to produce shells, and it is these shelly fossils that the scientists used.

Data from the tiny fossil shells, and data from new climate model runs, show that high latitude (~65 °S) sea temperatures were in excess of 20 °C. This seems very hot, but it is similar to more recent, better understood, greenhouse climates like that of the Late Cretaceous Period.


Invisible Scientific Debates Accomplish Nothing

by Donna Laframboise, April 23, 2018 in ClimateChangeDispatch

SPOTLIGHT: After the Intergovernmental Panel on Climate Change (IPCC) report was released in 2007, its dramatic findings of species extinction were repeatedly emphasized by chairman Rajendra Pachauri.

BIG PICTURE: When it examined the question of species extinction, the 2007 IPCC report relied heavily on a single piece of research – a Nature cover storypublished early in 2004. Written by Chris Thomas and 18 others, this was the source of Pachauri’s claim that climate change threatened 20 to 30% of the world’s species.

The Resilience of a Coralline Red Algae to Ocean Acidification

by  Donald et al. 2017, in CO2Science from Géochim.Cosmochim.Acta

The influence of pHsw on both pHcf and the calcification rate of Neogoniolithon is plotted in Figure 1 below. As indicated there, this coralline algal species is able to elevate its pHcf so as to increase its rate of calcification under moderate levels of ocean acidification (pHsw of 7.91 and 8.05), which increase the authors say is “most likely due to CO2-fertilization of [algal] photosynthesis” that is limited in Neogoniolithon at these lower pCO2 conditions. (….)

Retraction request for Harvey et al. attack paper on Dr. Susan Crockford

by Dr. S. Crockford, in A. Watts, December 5, 2017 in WUWT

Essay by Dr. Susan Crockford (republished from her website )on Retraction request to Bioscience: FOIA emails document another harsh criticism of Amstrup’s 2007 polar bear model

Today I sent a letter to the editors of the journal Bioscience requesting retraction of the shoddy and malicious paper by Harvey et al. (Internet blogs, polar bears, and climate-change denial by proxy) published online last week.

The letter reveals information about the workings of the polar bear expert inner circle not known before now, so grab your popcorn.

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Oxygen-18 Stability in Foraminifera fossils, implications in paleoclimatology

by Andy May, November 4, 2017

18O is a rare isotope of oxygen. The ratio of 18O to the normal 16O in foraminifera fossils (“forams”) can be used to estimate paleo-ocean temperatures. Higher values mean lower temperatures. A recent article on (here) led me to Bernard, et al., 2017, which has experimental data that suggest 18O concentrations can be altered in fossils by solid-state diffusion after fossilization. This can corrupt the measurement and the resulting calculated temperature

The End Of The Ocean Acidification Scare For Corals

by McCulloch et al., 2017, October 2017,  in co2science

Paper Reviewed: McCulloch, M.T., D’Olivo, J.P., Falter, J., Holcomb, M. and Trotter, J.A. 2017. Coral calcification in a changing world and the interactive dynamics of pH and DIC upregulation. Nature Communications 8: 15686, DOI:10.1038/ncomms15686

(…) The implications of the above findings are enormous, for they reveal that “pHcf upregulation occurs largely independent of changes in seawater carbonate chemistry, and hence ocean acidification,” demonstrating “the ability of the coral to ‘control’ what is arguably one of its most fundamental physiological processes, the growth of its skeleton within which it lives.

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The Impact of Elevated CO2 on a Widespread Ectomycorrhizal Fungi

by McCormack et al., 2017, September 18, 2017 in FungalEcology

In light of the above findings, it would appear that, given the near-global distribution of this EM fungi and its importance in stimulating ecosystem productivity, the positive impact of elevated CO2 on C. geophilumproduction (~50% increase for a 200 ppm rise) represents a welcomed benefit for the future of Earth’s forests.