Archive for November, 2020

Sea angels and sea butterflies reveal climate change consequences

Sea Angels and Sea Butterflies Reveal Climate Change Consequences
Sea angels are pteropods (and get their name from the Greek words for “wing” and “foot”) and their survival—or not—may serve as an indicator of ocean health. Credit: Getty Images

These winged water-dwellers are sea angels, floating marine slugs that may be the “canary in the coal mine” for severe ocean acidification caused by modern global warming.

Sea angels and their fluttering counterparts, sea butterflies, are pteropods. Pteropods first evolved in the early Cretaceous period, sharing the planet with dinosaurs and ammonites. The marine slugs are ancient and remarkably resilient; they have survived periods of major global extinctions and environmental changes, according to a study published in October 2020 in the journal Proceedings of the National Academy of SciencesIn addition, they are the only living creature of their kind with a solid fossil record, so they are uniquely situated to help researchers determine the effects of global change on the marine environment.

Continue reading ‘Sea angels and sea butterflies reveal climate change consequences’

Ocean acidification and short‐term organic matter enrichment alter coral reef sediment metabolism through different pathways

Ocean acidification (OA) and organic matter (OM) enrichment (due to coastal eutrophication) could act in concert to shift coral reef carbonate sediments from a present state of net calcification to a future state of net dissolution, but no studies have examined the combined effect of these stressors on sediment metabolism and dissolution. This study used 22‐hour incubations in flume aquaria with captive sediment communities to measure the combined effect of elevated pCO2 (representing Ocean Acidification) and particulate organic carbon (representing coastal eutrophication) on coral reef sediment gross primary productivity (GPP), respiration (R), and net calcification (Gnet). Relative to control sediment communities, both OA (pCO2 ~ 1000 μatm) and OM enrichment (~ + 40 μmol C L‐1) significantly decreased rates of sediment Gnet by 1.16 and 0.18 mmol CaCO3 m‐2 h‐1, respectively, but the mechanism behind this decrease differed. The OA‐mediated transition to net dissolution was physiochemical, as rates of GPP and R remained unaffected and dissolution was solely enhanced by a decline in the aragonite saturation state (Ωarg) of the overlying water column and the physical factors governing the porewater exchange rate with this overlying water column. In contrast, the OM‐mediated decline in Gnet was due to a decline in the overlying seawater Ωarg due to the increased respiratory addition of CO2. The decrease in Gnet in response to a combination of both stressors was additive (‐ 0.09 mmol CaCO3 m‐2 h‐1 relative to OA alone) but this decrease did not significantly differ from the individual effect of either stressor. In this study OA was the primary driver of future carbonate sediment dissolution, but longer‐term experiments with chronic organic matter enrichment are required.

Continue reading ‘Ocean acidification and short‐term organic matter enrichment alter coral reef sediment metabolism through different pathways’

Role of biological activity in mediating acidification in a coastal upwelling zone at the east coast of Hainan Island

Highlights

  • Three types (relief/aggravation/minor) of biological contribution to upwelling-induced acidification are quantitatively revealed at the east coast of Hainan Island.
  • Behaviors of carbonate chemistry and dissolved oxygen in upwelled waters are distinct due to different biological mediation between the nearshore and offshore regimes.
  • Aerobic respiration intensifies acidification in the subsurface of the nearshore area during a coastal upwelling.

Abstract


Coastal upwelling that brings to the surface both CO2- and nutrient-rich deep seawater is related to acidification and intense biological productivities in surface waters. However, the impact of biological activities on upwelling-induced acidification from nearshore to offshore areas in an upwelling zone remains insufficiently known. In this paper, we present daily records of high-resolution profiles of carbonate chemistry and hydrographic parameters from the nearshore to the offshore upwelling zone off the east coast of Hainan Island (ECH) in July 2014 (summer season). A three end-member mixing model was adopted to discriminate biological processes from physical mixing and to further semiquantitatively diagnose biological contribution to the upwelling-induced acidification. The results show divergent responses in pH, aragonite saturation state (ΩAr) and biomediated nonconservative dissolved inorganic carbon (ΔDIC) at depths of 10 m–30 m between nearshore and offshore regimes under the on-going coastal upwelling, which were attributed to the distinct roles of biological activities in mediating acidification in the upper 30 m across the ECH. Specifically, in the offshore regime, enhanced photosynthesis reduced the upwelling-induced acidification by 40% (i.e., type C: relief role), whereas aerobic respiration increased acidification in the subsurface waters of the nearshore regime by 15% (i.e., type B: aggravation role). This led to the pH and ΩAr minimum in upwelled waters along the transect from the nearshore to the offshore. In contrast, the biological contribution was almost negligible over surface waters in the nearshore regime because of the balance between net community productivity and net community calcification (i.e., type A: limited or minor role).

Continue reading ‘Role of biological activity in mediating acidification in a coastal upwelling zone at the east coast of Hainan Island’

Ocean acidification – a card game simulation – climate change

Instructions for Teachers

The pages are set so that, when printed double sided, they have a back and front, enabling for easy sorting. Before you print the whole deck, test your settings by printing the first two pages of cards, to check alignment. If it doesn’t match, then its likely to do with how the printer flips the page (either long end or short end), so make sure it is on the flipped on the long end. If you don’t want backs, then print every second page. There are two sizes of cards, mini and large, so have a look at both before you print.

Contents: 8x Hydrogen Cards, 8x Hydrogen Carbonate Cards, 19x Calcium Cards, 19x

Carbonate Cards, 1x Information Card

This card game works in 4 rounds. This works best in groups of 4, but can work with less or if necessary, up to 5 players per deck. Each player is role playing as a crab.

Round one: The game starts by placing all of the Calcium and Carbonate Ion Cards face down on the table, as well as two hydrogen and two hydrogen carbonate cards. Each person picks up 4 positive ion cards and 4 negative ion cards. The goal is to match. Calcium with Carbonate. If you have 4 pairs, your shell grows. 3 pairs means enough minerals have been gathered to repair their shell. 2 pairs means damage cannot be repaired, but doesn’t worsen and 1 pair means the shell gets further damage and cannot be repaired. Record the scores on a tally card.

Round two-four: At the end of the first round and each round after, all the cards are returned to the table, face down and an additional two hydrogen and two hydrogen carbonate cards are added, symbolising the acidification of the ocean through the dissolving of more CO2. Same rules for shell repair apply.

Person with the most points at the end wins (pairs). Enjoy.

From teacherspayteachers.com

Continue reading ‘Ocean acidification – a card game simulation – climate change’

Ocean acidification modifies biomolecule composition in organic matter through complex interactions

The main source of marine organic carbon (OC) is autotrophic production, while heterotrophic degradation is its main sink. Increased anthropogenic CO2 release leads to ocean acidification and is expected to alter phytoplankton community composition, primary production rates and bacterial degradation processes in the coming decades with potential consequences for dissolved and particulate OC concentration and composition. Here we investigate effects of increased pCO2 on dissolved and particulate amino acids (AA) and carbohydrates (CHO), in arctic and sub-arctic planktonic communities in two large-scale mesocosm experiments. Dissolved AA concentrations responded to pCO2/pH changes during early bloom phases but did not show many changes after nutrient addition. A clear positive correlation in particulate AA was detected in post-bloom phases. Direct responses in CHO concentrations to changing pCO2/pH were lacking, suggesting that observed changes were rather indirect and dependent on the phytoplankton community composition. The relative composition of AA and CHO did not change as a direct consequence of pCO2 increase. Changes between bloom phases were associated with the prevailing nutrient status. Our results suggest that biomolecule composition will change under future ocean conditions but responses are highly complex, and seem to be dependent on many factors including bloom phase and sampling site.

Continue reading ‘Ocean acidification modifies biomolecule composition in organic matter through complex interactions’

Impact of ocean acidification to coral skeletons – CT analysis (video)

This is a video from our recent paper on “Crumbling Reefs and Cold-Water Coral Habitat Loss in a Future Ocean: Evidence of “Coralporosis” as an Indicator of Habitat Integrity”. It shows how ocean acidification can lead to ‘coralporosis’ in dead coral skeletons, and uses images taken at the Diamond Lightsource Synchrotron facility https://www.frontiersin.org/articles/
Continue reading ‘Impact of ocean acidification to coral skeletons – CT analysis (video)’

CO2 reduction for C2+ in seawater using a graphitic frustrated Lewis pair catalyst

Ocean acidification due to the absorption of 40% of the world’s anthropogenic CO2 emissions severely affects the faltering marine ecosystem and the economy. However, there are few reports on reducing CO2 dissolved in seawater. Herein, we introduce an electrochemical CO2 reduction battery system for use in seawater with a graphitic frustrated Lewis pair catalytic cathode doped with boron and nitrogen (BN-GFLP). BN-GFLP converts CO2 dissolved in seawater to multi-carbon (C2+) products during the discharge process, thus increasing the pH of intentionally acidified seawater from 6.4 to 8.0 with more than 87% Faradaic efficiency. In computational chemistry and spectroscopy, BN-GFLP binds CO2 in a unique manner that enables exothermic C–C coupling pathway to deliver 95% selectivity for valuable C2+ products. Based on our results, we suggest a molecular design strategy for next-generation CO2 reduction catalysts for both green oceans and the atmosphere.

Continue reading ‘CO2 reduction for C2+ in seawater using a graphitic frustrated Lewis pair catalyst’

Environmental pharmaceuticals and climate change: the case study of carbamazepine in M. galloprovincialis under ocean acidification scenario

Highlights

  • Combined effects of carbamazepine and reduced pH were investigated in M. galloprovincialis.
  • Hypercapnia had a limited influence on carbamazepine accumulation.
  • Interactive effects were observed at both transcriptional and cellular level.
  • Immune system, cellular homeostasis and oxidative processes were mostly affected.
  • Weighted elaboration of results revealed higher hazard by multiple stressors.

Abstract
Contaminants of emerging concern and ocean changes are key environmental stressors for marine species with possibly synergistic, but still unexplored, deleterious effects. In the present study the influence of a simulated ocean acidification scenario (pH = 7.6) was investigated on metabolism and sub-lethal effects of carbamazepine, CBZ (1 µg/L), chosen as one of the most widely diffused pharmaceuticals in marine organisms. A multidisciplinary approach was applied on mussels, M. galloprovincialis, integrating measurement of drug bioaccumulation with changes in the whole transcriptome, responsiveness of various biochemical and cellular biomarkers including immunological parameters, lipid and oxidative metabolism, onset of genotoxic effects. Chemical analyses revealed a limited influence of hypercapnia on accumulation and excretion of CBZ, while a complex network of biological responses was observed in gene expression profile and functional changes at cellular level. The modulation of gamma-aminobutyric acid (GABA) pathway suggested similarities with the Mechanism of Action known for vertebrates: immune responses, cellular homeostasis and oxidative system represented the processes targeted by combined stressors. The overall elaboration of results through a quantitative Weight of Evidence model, revealed clearly increased cellular hazard due to interactions of CBZ with acidification compared to single stressors.

Continue reading ‘Environmental pharmaceuticals and climate change: the case study of carbamazepine in M. galloprovincialis under ocean acidification scenario’

The state of ocean acidification

Ocean acidification is often thought of as a future impact of our changing climate. But exactly what is it, what are its impacts and is it really a problem of the future?

As reported in the CSIRO and Bureau of Meteorology’s latest State of the Climate report, oceans around Australia are acidifying 10 times faster than at any point in the last 300 million years. When coupled with ocean warming and deoxygenation, this is putting considerable pressure on our marine environments. Recent research from CSIRO and AIMS has highlighted the changing conditions on the Great Barrier Reef. Drawing on over a decade of observations collected as part of Australia’s Integrated Marine Observing System (IMOS) the team found that the Reef’s rich carbonate seafloor is not buffering against ocean acidification, a process that might offset ocean acidification.

The future is now for the Great Barrier Reef

New research published by the Australian Institute of Marine Science (AIMS) and CSIRO has shown that ocean acidification is no longer a thing of climate projections, but a present-day reality.

Bleached corals with small fish in background
The oceans are slowing climate change by absorbing excess heat, but changes in carbon chemistry of sea water is contributing to coral bleaching. © CSIRO, Christopher Doropoulos.
Continue reading ‘The state of ocean acidification’

Simulated climate change scenarios impact the reproduction and early life stages of a soft coral

Highlights

  • A change in the timing of onset of the soft coral breeding event occurred under elevated temperature and reduced pH seawater conditions.
  • A disruption of the synchronicity of the breeding event occurred under elevated temperature and reduced pH seawater conditions.
  • End-of-the-century seawater conditions are expected to affect the reproduction of the soft coral Rhytisma fulvum.
  • Planula survival and polyp metamorphosis rates were significantly reduced under both end-of-the-century seawater conditions compared to propagules reared under ambient conditions.
  • The photosynthetic capacity of the parent soft coral colonies was reduced under the end-of-the-century seawater conditions in comparison to those under the ambient conditions.

Abstract

Coral reefs are threatened worldwide by global climate change, manifested in anthropogenic ocean warming and acidification. Despite the importance of coral sexual reproduction for the continuity of coral reefs, our understanding of the extent of the impact of climate change on coral sexual reproduction, particularly on coral reproductive phenology and early life stages, is limited. Here, we experimentally examined the effects of predicted end-of-the-century seawater conditions on the sexual reproduction and photosynthetic capacity of a Red-Sea zooxanthellate octocoral, Rhytisma fulvum. Sexually mature colonies were exposed to ambient temperature and pH conditions and to Representative Concentration Pathway (RCP) conditions (4.5 and 8.5), five weeks prior to their expected surface-brooding event. The reproductive phenology of the colonies under the simulated seawater conditions was compared to that on the natural reef. In addition, subsequent planulae development and their metamorphosis into primary polyps under the same RCP conditions as their parent colonies were monitored in a running seawater system. The results reveal that both RCP conditions led to a change in the timing of onset of the surface-brooding event and its synchronicity. In contrast, the surface-brooding event under ambient conditions co-occurred with that of the in-situ reef colonies and maintained its synchrony. Similarly, planula survival and polyp metamorphosis rate were significantly reduced under both RCP conditions compared to propagules reared under ambient conditions. In addition, the photosynthetic capacity of the parent colonies under both RCPs showed a reduction relative to that under the ambient conditions in the experiment, suggesting a reduction in carbon fixation during the late stages of gametogenesis. While our findings indicate that octocoral reproductive phenology is affected by environmental changes, further work is required in order to elucidate the long-term implications for the R. fulvum population in the northern Red Sea.

Continue reading ‘Simulated climate change scenarios impact the reproduction and early life stages of a soft coral’

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Ocean acidification in the IPCC AR5 WG II

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