Solar irradiance changes and phytoplankton productivity in Earth's ocean following astrophysical ionizing radiation events

Solar irradiance changes and phytoplankton productivity in Earth's ocean following astrophysical ionizing radiation events

Authors:

Neale et al

Abstract:

Two atmospheric responses to simulated astrophysical ionizing radiation events significant to life on Earth are production of odd-nitrogen species, especially NO2, and subsequent depletion of stratospheric ozone. Ozone depletion increases incident short-wavelength ultraviolet radiation (UVB, 280-315 nm) and longer ( greater than 600 nm) wavelengths of photosynthetically available radiation (PAR, 400 -700 nm). On the other hand, the NO2 haze decreases atmospheric transmission in the long-wavelength UVA (315-400 nm) and short wavelength PAR. Here we use the results of previous simulations of incident spectral irradiance following an ionizing radiation event to predict changes in Terran productivity focusing on photosynthesis of marine phytoplankton. The prediction is based on a spectral model of photosynthetic response developed for the dominant genera in central regions of the ocean (Synechococcus and Prochlorococcus), and remote-sensing based observations of spectral water transparency, temperature, wind speed and mixed layer depth. Predicted productivity declined after a simulated ionizing event, but the effect integrated over the water column was small. For integrations taking into account the full depth range of PAR transmission (down to 0.1% of utilizable PAR), the decrease was at most 2-3% (depending on strain), with larger effects (5-7%) for integrations just to the depth of the surface mixed layer. The deeper integrations were most affected by the decreased utilizable PAR at depth due to the NO2 haze, whereas shallower integrations were most affected by the increased surface UV.

Warmer Temperatures INCREASE Phytoplankton Biodiversity and Photosynthesis

Warmer temperatures increase biodiversity and photosynthesis in phytoplankton, researchers at the University of Exeter and Queen Mary University of London (QMUL) have found. Globally, phytoplankton -- microscopic water-borne plants -- absorb as much carbon dioxide as tropical rainforests and so understanding the way they respond to a warming climate is crucial.

The groundbreaking study, published in the journal PLOS Biology, was carried out over five years using artificially warmed ponds that simulated the increases in temperature expected by the end of the century.

The researchers found that phytoplankton in ponds that had been warmed by four degrees, had 70% more species and higher rates of photosynthesis, and as a result, have the potential to remove more carbon dioxide from the atmosphere.

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~13% of Calcareous Nannoplankton Survived the K-Pg/K-T Mass Extinction

Calcareous nannoplankton assemblage changes linked to paleoenvironmental deterioration and recovery across the Cretaceous–Paleogene boundary in the Betic Cordillera (Agost, Spain)

Authors:

Lamolda et al

Abstract:

Investigations of calcareous nannoplankton assemblages including species richness and abundance data were performed across the K–Pg boundary interval at Agost (SE Spain), between − 100 cm and + 100 cm, below and, respectively, above the boundary, at a considerable high resolution averaging 2 cm. From a total of 98 species of the Upper Maastrichtian, only 13 survived mass extinction, while the rest of the 86% vanished in the K–Pg fallout layer. A slight progressive decline in species richness and abundance was observed toward the top of the Maastrichtian, where mixed assemblages, consisting of both cold-water taxa and typical Tethyan ones are present. Four successive acme events were observed, i.e. Markalius inversus and the calcareous dinoflagellate genus Thoracosphaera starting from the base of the Paleocene, followed by those of Braarudosphaera bigelowii and Neobiscutum parvulum. The most prominent acme intervals belong to Thoracosphaera spp. and B. bigelowii, opportunistic taxa, for which the survival strategy may be linked to their capability to encyst and survive severe environmental deterioration. At the upper part of the studied succession, calcareous nannoplankton assemblages are already dominated by survivor species, as well as incoming ones, showing an early pioneer calcareous nannoplankton ecosystems about 35–40 kyr after the K–Pg boundary. Correlation between the calcareous nannoplankton assemblage fluctuation, including species richness and abundance, and the paleoenvironmental changes, such as the eustatic and climatic modifications, are also discussed.

Ocean Warming, NOT Acidification, Impacts Calicified Plankton (coccolithophore) Growth

Ocean warming, not acidification, controlled coccolithophore response during past greenhouse climate change

Authors:

Gibbs et al

Abstract:

Current carbon dioxide emissions are an assumed threat to oceanic calcifying plankton (coccolithophores) not just due to rising sea-surface temperatures, but also because of ocean acidification (OA). This assessment is based on single species culture experiments that are now revealing complex, synergistic, and adaptive responses to such environmental change. Despite this complexity, there is still a widespread perception that coccolithophore calcification will be inhibited by OA. These plankton have an excellent fossil record, and so we can test for the impact of OA during geological carbon cycle events, providing the added advantages of exploring entire communities across real-world major climate perturbation and recovery. Here we target fossil coccolithophore groups (holococcoliths and braarudosphaerids) expected to exhibit greatest sensitivity to acidification because of their reliance on extracellular calcification. Across the Paleocene-Eocene Thermal Maximum (56 Ma) rapid warming event, the biogeography and abundance of these extracellular calcifiers shifted dramatically, disappearing entirely from low latitudes to become limited to cooler, lower saturation-state areas. By comparing these range shift data with the environmental parameters from an Earth system model, we show that the principal control on these range retractions was temperature, with survival maintained in high-latitude refugia, despite more adverse ocean chemistry conditions. Deleterious effects of OA were only evidenced when twinned with elevated temperatures.

SURPRISE! Coccolithophores, Calcium Shelled Plankton, Actually Grow MORE With Increased Carbon dioxide, NOT Less

Coccolithophores--tiny calcifying plants that are part of the foundation of the marine food web--have been increasing in relative abundance in the North Atlantic over the last 45 years, as carbon input into ocean waters has increased. Their relative abundance has increased 10 times, or by an order of magnitude, during this sampling period. This finding was diametrically opposed to what scientists had expected since coccolithophores make their plates out of calcium carbonate, which is becoming more difficult as the ocean becomes more acidic and pH is reduced.

These findings were reported in the November 26th edition of Science and based on analysis of nearly a half century of data collected by the long-running Sir Alister Hardy Foundation (SAHFOS) Continuous Plankton Recorder sampling program.

"The results show both the power of long-term time-series of ocean observations for deciphering how marine microbial communities are responding to climate change and offer evidence that the ocean garden is changing," said Dr. William Balch, senior research scientist at Bigelow Laboratory for Ocean Sciences and a co-author of the paper. "We never expected to see the relative abundance of coccolithophores to increase 10 times in the North Atlantic over barely half a century. If anything, we expected that these sensitive calcifying algae would have decreased in the face of increasing ocean acidification (associated with increasing carbon dioxide entering the ocean from the burning of fossil-fuels). Instead, we see how these carbon-limited organisms appear to be using the extra carbon from CO2 to increase their relative abundance by an order of magnitude.

"This provides one example on how marine communities across an entire ocean basin are responding to increasing carbon dioxide levels. Such real-life examples of the impact of increasing CO2 on marine food webs are important to point out as the world comes together in Paris next week at the United Nations Conference on Climate Change," Balch added.

"Something strange is happening here, and it's happening much more quickly than we thought it should," said Anand Gnanadesikan, associate professor in the Morton K. Blaustein Department of Earth and Planetary Sciences at Johns Hopkins and one of the study's five authors.

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Evidence of Heavy Metal Poisoning From Ordovician Mass Extinction in Marine Plankton

Several Palaeozoic mass extinction events during the Ordovician and Silurian periods (ca. 485 to 420 to million years ago) shaped the evolution of life on our planet. Although some of these short-lived, periodic events were responsible for eradication of up to 85% of marine species, the exact kill-mechanism responsible for these crises remains poorly understood.

An international team led by Thijs Vandenbroucke (researcher at the French CNRS and invited professor at UGent) and Poul Emsbo (US Geological Survey) initiated a study to investigate a little known association between 'teratological' or 'malformed' fossil plankton assemblages coincident with the initial stages of these extinction events.

In a paper just published in Nature Communications, they present evidence that malformed fossil remains of marine plankton from the late Silurian (415 million years ago) contain highly elevated concentrations of heavy metals, such as iron, lead, and arsenic. These are well-known toxins that cause morphologic abnormalities in modern aquatic organisms; which led the authors to conclude that metal poisoning caused the malformation observed in these ancient organisms and may have contributed to their extinction and that of many other species.

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Phytoplankton Amplifying Arctic Greenhouse Warming

Amplified Arctic warming by phytoplankton under greenhouse warming

Authors:

Park et al

Abstract:

Phytoplankton have attracted increasing attention in climate science due to their impacts on climate systems. A new generation of climate models can now provide estimates of future climate change, considering the biological feedbacks through the development of the coupled physical–ecosystem model. Here we present the geophysical impact of phytoplankton, which is often overlooked in future climate projections. A suite of future warming experiments using a fully coupled ocean−atmosphere model that interacts with a marine ecosystem model reveals that the future phytoplankton change influenced by greenhouse warming can amplify Arctic surface warming considerably. The warming-induced sea ice melting and the corresponding increase in shortwave radiation penetrating into the ocean both result in a longer phytoplankton growing season in the Arctic. In turn, the increase in Arctic phytoplankton warms the ocean surface layer through direct biological heating, triggering additional positive feedbacks in the Arctic, and consequently intensifying the Arctic warming further. Our results establish the presence of marine phytoplankton as an important potential driver of the future Arctic climate changes.

Albian/Cenomanian Cretaceous Marine Dinoflagellates Found...Trapped in Amber!

Blowin' in the wind… 100 Ma old multi-staged dinoflagellate with sexual fusion trapped in amber: Marine–freshwater transition

Authors:

1. Edwige Masure (a)
2. Jean Dejax (b)
3. Gaël De Ploëg (c)

Affiliations:

a. Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P UMR7207 – CNRS, MNHN, UPMC Univ. Paris 6, Université Pierre et Marie Curie, 75252 Paris Cedex 05, France

b. Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P UMR7207 – CNRS, MNHN, UPMC Univ. Paris 6, Muséum national d'Histoire naturelle, 57 rue Cuvier, 75231 Paris Cedex 05, France

c. 3 rue De la Rochefoucauld, 60180 Nogent-sur-Oise, France

Abstract:

Here we report the unexpected discovery of multi-staged dinoflagellates with organic cellular contents from a paralic habitat trapped in 100 million year (100 Ma) old amber. Amber formed from resin, a fluid medium, that trapped, then remarkably embedded and preserved soft parts of organisms usually destroyed by fossilization processes. We assume that the marine-costal dinoflagellates reached the sticky resin carried away by the wind, inside spray droplets. We answer to a fundamental question dealing with the Peridiniaceae: the paratabulation of Cretaceous cysts reflects the tabulation of Cretaceous thecae. We provide the first life cycle of the fossil record with evidence of cellulosic thecae, sexual fusion and zygote. We highlight an ancestral behaviour for the sexual phase: naked gametes complete fusion outside of gametic thecae, a process known in rare extant Peridinium species. The new taxon, Succiniperidinium inopinatum gen. et sp. nov., belongs to the Peridiniaceae and shares characters with extant marine-brackish Scrippsiella and two freshwater Peridinium clades identified by morphological characters (tabulation, cingular plates, ecdysis, plasmogamy) and molecular phylogenies. Understanding the processes of marine–freshwater transition in microbial lineages is a central goal in evolutionary ecology. Marine dinoflagellates passed through the osmotic barrier and the studies of marine-costal Cretaceous species help to understand the adaptation and the diversification of these species. We discuss the migration according to biological, paleontological and molecular phylogenies data and suggest that the freshwater colonization was the result of Cretaceous species adapted to costal habitats; their lineage isolated in ponds following the Cenozoic global sea-level fall passed through the osmotic barrier. A Scrippsiella-like group (i.e. Subtilisphaera terrula, Palaeoperidinium cretaceum and Succiniperidinium inopinatum gen. et sp. nov.) is suggested as intermediate species in the Peridinium freshwater colonization line.