Cymodocea nodosa response to simulated CO2-driven ocean acidification: a first insight from global transcriptome profiling

Global climate changes are imposing multiple pressures to marine organisms. The rising atmospheric CO2 concentration is causing substantial changes in ocean physics, chemistry and biology. At least three synergic environmental stressors have been recognized as primary driven by CO2 emissions: ocean warming, oxygen loss and ocean acidification. The effects of CO2-driven ocean acidification on seagrass metabolism remain largely understudied. A few studies have been conducted near submarine volcanic vents, which mimic the future ocean acidification scenarios, allowing researchers to investigate the performance of marine organisms under long-term exposure to high-CO2 levels. Apart from these, some mesocosm-based experiments have investigated growth and physiological responses to high CO2. For this work, we built an outdoor mesocosm facility at the Centre of Marine Sciences’ field station in Algarve, Portugal, to experimentally manipulate CO2 levels and investigate the effects of high-CO2/low pH on seagrass metabolism and underlying molecular mechanisms. Cymodocea nodosa plants were collected in Cadiz Bay at the end of January 2014 and transported to the mesocosm facility. After a one week acclimation period, C. nodosa were either kept under normal (400 ppm) or elevated (1200 ppm) CO2 concentration for 12 days. Water physico-chemical parameters, irradiance, and chlorophyll-fluorescence-derived photosynthetic parameters were monitored on a daily basis. Here we present, for the first time in this species, results obtained using Illumina RNAseq technology and de-novo transcriptome assembly. Using C. nodosa RNAs extracted at the beginning and the end of the experiment, we assembled more than 70 thousands unique transcripts and were able to annotate more than 90% of them using the Annocript pipeline. Differential expression analysis revealed about 500 transcripts significantly differentially regulated between plants kept under control and high-CO2 conditions. Pathways showing largest changes in gene expression included isoprenoid and amino-acid biosynthesis, porphyrin-containing compound metabolism, amine and polyamine biosynthesis, lipid and carbohydrate metabolism. Transcriptome sequencing also significantly increases the molecular resources available for C. nodosa, almost completely absent before this study.

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Cymodocea nodosa response to simulated CO2-driven ocean acidification: a first insight from global transcriptome profiling

10.7287/peerj.preprints.1057 ◽

2015 ◽

Author(s):

Miriam Ruocco ◽

Procaccini Gabriele ◽

Francesco Musacchia ◽

Remo Sanges ◽

Irene Olivé ◽

...

Keyword(s):

Ocean Acidification ◽

Molecular Mechanisms ◽

Transcriptome Assembly ◽

Co2 Concentration ◽

Marine Organisms ◽

Photosynthetic Parameters ◽

Cymodocea Nodosa ◽

Field Station ◽

High Co2 ◽

Co2 Levels

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Ocean Acidification: Calcifying Marine Organisms

EDIS ◽

10.32473/edis-fa220-2020 ◽

2020 ◽

Vol 2020 (2) ◽

pp. 4

Author(s):

Joseph Henry ◽

Joshua Patterson ◽

Lisa Krimsky

Keyword(s):

Ocean Acidification ◽

Atmospheric Carbon Dioxide ◽

Carbonic Acid ◽

Essential Element ◽

Co2 Concentration ◽

Marine Organisms ◽

Atmospheric Co2 ◽

Hydrogen Ions ◽

Excess Hydrogen ◽

Carbonate Ions

Rising atmospheric carbon dioxide (CO2) concentration leading to ocean acidification is a threat to marine ecosystems and organisms. As atmospheric CO2 rises, CO2 is driven into the ocean. When CO2 combines with seawater it makes carbonic acid. Carbonic acid then breaks down to form a hydrogen ion and a bicarbonate ion. Excess hydrogen ions building up over time result in decreased seawater pH. Furthermore, the excess hydrogen ions combine with carbonate ions in the water, resulting in fewer available carbonate ions for marine calcifiers. These carbonate ions are an essential element for marine calcifiers and their decreased availability is of increasing concern. The overall change in pH and available carbonate ions has been shown to have direct impacts on physiology, behavior, and calcification rates of marine organisms. Coastal Florida boasts an abundance and diversity of calcifying organisms that stand to be impacted by the altered carbonate chemistry resulting from increased atmospheric CO2 levels. This publication will focus on the impacts of ocean acidification on Calcification. Specifically focusing on how calcification in corals, bivalves, echinoderms and planktonic organisms are being impacte.

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Different Pathways to an Early Eocene Climate

10.31223/x5bd0n ◽

2021 ◽

Author(s):

Matthew Henry ◽

Geoffrey Vallis

Keyword(s):

Heat Capacity ◽

Surface Temperature ◽

Land Surface ◽

Co2 Concentration ◽

Surface Heat ◽

The Arctic ◽

Early Eocene ◽

Surface Temperature Change ◽

High Co2 ◽

Co2 Levels

The early Eocene was characterised by much higher temperatures and a smaller equator-to-pole surface temperature gradient than today. Comprehensive climate models have been reasonably successful in simulating many features of that climate in the annual average. However, good simulations of the seasonal variations, and in particular the much reduced Arctic land temperature seasonality and associated much warmer winters, have proven more difficult. Further, aside from an increased level of greenhouse gases, it remains unclear what the key processes are that give rise to an Eocene climate, and whether there is a unique combination of factors that leads to agreement with available proxies. Here we use a very flexible General Circulation Model to examine the sensitivity of the modelled climate to differences in CO2 concentration, land surface properties, ocean heat transport, and cloud extent and thickness. Even in the absence of ice or changes in cloudiness, increasing the CO2 concentration leads to a polar-amplified surface temperature change because of increased water vapour and the lack of convection at high latitudes. Additional low clouds over Arctic land generally decreases summer temperatures and, except at very high CO2 levels, increases winter temperatures, thus helping achieve an Eocene climate. An increase in the land surface heat capacity, plausible given large changes in vegetation and landscape, also decreases the Arctic land seasonality. In general, various different combinations of factors -- high CO2 levels, changes in low-level clouds, and an increase in land surface heat capacity -- can lead to a simulation consistent with current proxy data.

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The Antioxidant Status of Soybean (Glycine max) Leaves Grown Under Natural CO2 Enrichment in the Field

Functional Plant Biology ◽

10.1071/pp9930275 ◽

1993 ◽

Vol 20 (3) ◽

pp. 275 ◽

Cited By ~ 27

Author(s):

M Badiani ◽

A D'annibale ◽

AR Paolacci ◽

F Miglietta ◽

A Raschi

Keyword(s):

Superoxide Dismutase ◽

Glycine Max ◽

Antioxidant Status ◽

Central Italy ◽

Substantial Reduction ◽

Co2 Concentration ◽

Ambient Air ◽

Glutathione Disulfide ◽

High Co2 ◽

Co2 Levels

The effects of progressively higher CO2 levels on the foliar antioxidant status were studied by growing soybean (Glycine max Merrill cv. Cresir) plants at decreasing distances from natural CO2 sources of geothermal origin in central Italy. When compared with neighbouring controls grown under normal CO2 concentration (C), soybean leaves grown at 2 × C, 7 × C and more than 20 × C showed a substantial reduction in the size of ascorbate pool and in the activity of Cu,Zn-superoxide dismutase; both the content of ascorbic acid and the activity of ascorbate peroxidase declined at 2 × C and 7 × C and recovered to the control values at 20 × C. The foliar titre of glutathione disulfide and the activities of glutathione disulfide reductase and Mn-superoxide dismutase progressively increased as CO2 concentration increased in ambient air. The results obtained suggest that the immanent risk of dioxygen toxicity associated with photosynthetic electron flow could be reduced in the presence of high CO2 levels. On the other hand, depending on both the CO2 exposure regimes and the cell compartment considered, high CO2 could promote oxidative processes which cause GSH oxidation and require an enhanced cellular ability to scavenge superoxide anion and hydrogen peroxide.

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Experimental assessments of marine species sensitivities to ocean acidification and co-stressors: how far have we come?

Canadian Journal of Zoology ◽

10.1139/cjz-2018-0198 ◽

2019 ◽

Vol 97 (5) ◽

pp. 399-408 ◽

Cited By ~ 22

Author(s):

Hannes Baumann

Keyword(s):

Ocean Acidification ◽

Species Interactions ◽

Molecular Mechanisms ◽

Experimental Studies ◽

Intraspecific Variability ◽

Marine Species ◽

Marine Organisms ◽

Single Experiment ◽

Experimental Approaches ◽

Marine Climate

Experimental studies assessing the potential impacts of ocean acidification on marine organisms have rapidly expanded and produced a wealth of empirical data over the past decade. This perspective examines four key areas of transformative developments in experimental approaches: (1) methodological advances; (2) advances in elucidating physiological and molecular mechanisms behind observed CO2effects; (3) recognition of short-term CO2variability as a likely modifier of species sensitivities (Ocean Variability Hypothesis); and (4) consensus on the multistressor nature of marine climate change where effect interactions are still challenging to anticipate. No single experiment allows predicting the fate of future populations. But sustaining the accumulation of empirical evidence is critical for more robust estimates of species reaction norms and thus for enabling better modeling approaches. Moreover, advanced experimental approaches are needed to address knowledge gaps including changes in species interactions and intraspecific variability in sensitivity and its importance for the adaptation potential of marine organisms to a high CO2world.

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Ocean acidification decreases plankton respiration: evidence from a mesocosm experiment

10.5194/bg-2015-608 ◽

2016 ◽

Cited By ~ 1

Author(s):

K. Spilling ◽

A. J. Paul ◽

N. Virkkala ◽

T. Hastings ◽

S. Lischka ◽

...

Keyword(s):

Primary Production ◽

Ocean Acidification ◽

Community Composition ◽

Carbon Fixation ◽

Plankton Community ◽

Community Respiration ◽

Carbon Export ◽

High Co2 ◽

Respiration Rates ◽

Co2 Levels

Abstract. Anthropogenic carbon dioxide (CO2) emissions are reducing the pH in the world's oceans. The plankton community is a key component driving biogeochemical fluxes, and the effect of increased CO2 on plankton is critical for understanding the ramifications of ocean acidification on global carbon fluxes. We determined the plankton community composition and measured primary production, respiration rates and carbon export (defined here as carbon sinking out of a shallow, coastal area) during an ocean acidification experiment. Mesocosms (~ 55 m3) were set up in the Baltic Sea with a gradient of CO2 levels initially ranging from ambient (~ 240 μatm), used as control, to high CO2 (up to ~ 1330 μatm). The phytoplankton community was dominated by dinoflagellates, diatoms, cyanobacteria and chlorophytes, and the zooplankton community by protozoans, heterotrophic dinoflagellates and cladocerans. The plankton community composition was relatively homogenous between treatments. Community respiration rates were lower at high CO2 levels. The carbon-normalized respiration was approximately 40 % lower in the high CO2 environment compared with the controls during the latter phase of the experiment. We did not, however, detect any effect of increased CO2 on primary production. This could be due to measurement uncertainty, as the measured total particular carbon (TPC) and combined results presented in this special issue suggest that the reduced respiration rate translated into higher net carbon fixation. The percent carbon derived from microscopy counts (both phyto- and zooplankton), of the measured total particular carbon (TPC) decreased from ~ 26 % at t0 to ~ 8 % at t31, probably driven by a shift towards smaller plankton (< 4 μm) not enumerated by microscopy. Our results suggest that reduced respiration lead to increased net carbon fixation at high CO2. However, the increased primary production did not translate into increased carbon export, and did consequently not work as a negative feedback mechanism for increasing atmospheric CO2 concentration.

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Ocean acidification decreases plankton respiration: evidence from a mesocosm experiment

Biogeosciences ◽

10.5194/bg-13-4707-2016 ◽

2016 ◽

Vol 13 (16) ◽

pp. 4707-4719 ◽

Cited By ~ 12

Author(s):

Kristian Spilling ◽

Allanah J. Paul ◽

Niklas Virkkala ◽

Tom Hastings ◽

Silke Lischka ◽

...

Keyword(s):

Primary Production ◽

Ocean Acidification ◽

Community Composition ◽

Carbon Fixation ◽

Plankton Community ◽

Community Respiration ◽

Carbon Export ◽

High Co2 ◽

Respiration Rates ◽

Co2 Levels

Abstract. Anthropogenic carbon dioxide (CO2) emissions are reducing the pH in the world's oceans. The plankton community is a key component driving biogeochemical fluxes, and the effect of increased CO2 on plankton is critical for understanding the ramifications of ocean acidification on global carbon fluxes. We determined the plankton community composition and measured primary production, respiration rates and carbon export (defined here as carbon sinking out of a shallow, coastal area) during an ocean acidification experiment. Mesocosms ( ∼  55 m3) were set up in the Baltic Sea with a gradient of CO2 levels initially ranging from ambient ( ∼  240 µatm), used as control, to high CO2 (up to ∼  1330 µatm). The phytoplankton community was dominated by dinoflagellates, diatoms, cyanobacteria and chlorophytes, and the zooplankton community by protozoans, heterotrophic dinoflagellates and cladocerans. The plankton community composition was relatively homogenous between treatments. Community respiration rates were lower at high CO2 levels. The carbon-normalized respiration was approximately 40 % lower in the high-CO2 environment compared with the controls during the latter phase of the experiment. We did not, however, detect any effect of increased CO2 on primary production. This could be due to measurement uncertainty, as the measured total particular carbon (TPC) and combined results presented in this special issue suggest that the reduced respiration rate translated into higher net carbon fixation. The percent carbon derived from microscopy counts (both phyto- and zooplankton), of the measured total particular carbon (TPC), decreased from ∼  26 % at t0 to ∼  8 % at t31, probably driven by a shift towards smaller plankton (< 4 µm) not enumerated by microscopy. Our results suggest that reduced respiration leads to increased net carbon fixation at high CO2. However, the increased primary production did not translate into increased carbon export, and consequently did not work as a negative feedback mechanism for increasing atmospheric CO2 concentration.

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Effects of ocean acidification on pelagic carbon fluxes in a mesocosm experiment

Biogeosciences ◽

10.5194/bg-13-6081-2016 ◽

2016 ◽

Vol 13 (21) ◽

pp. 6081-6093 ◽

Cited By ~ 13

Author(s):

Kristian Spilling ◽

Kai G. Schulz ◽

Allanah J. Paul ◽

Tim Boxhammer ◽

Eric P. Achterberg ◽

...

Keyword(s):

Organic Carbon ◽

Primary Production ◽

Ocean Acidification ◽

Bacterial Production ◽

Co2 Concentration ◽

Carbon Fluxes ◽

Co2 Levels ◽

Standing Stocks ◽

Co2 Treatment ◽

Ambient Co2

Abstract. About a quarter of anthropogenic CO2 emissions are currently taken up by the oceans, decreasing seawater pH. We performed a mesocosm experiment in the Baltic Sea in order to investigate the consequences of increasing CO2 levels on pelagic carbon fluxes. A gradient of different CO2 scenarios, ranging from ambient ( ∼  370 µatm) to high ( ∼  1200 µatm), were set up in mesocosm bags ( ∼  55 m3). We determined standing stocks and temporal changes of total particulate carbon (TPC), dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and particulate organic carbon (POC) of specific plankton groups. We also measured carbon flux via CO2 exchange with the atmosphere and sedimentation (export), and biological rate measurements of primary production, bacterial production, and total respiration. The experiment lasted for 44 days and was divided into three different phases (I: t0–t16; II: t17–t30; III: t31–t43). Pools of TPC, DOC, and DIC were approximately 420, 7200, and 25 200 mmol C m−2 at the start of the experiment, and the initial CO2 additions increased the DIC pool by ∼  7 % in the highest CO2 treatment. Overall, there was a decrease in TPC and increase of DOC over the course of the experiment. The decrease in TPC was lower, and increase in DOC higher, in treatments with added CO2. During phase I the estimated gross primary production (GPP) was ∼  100 mmol C m−2 day−1, from which 75–95 % was respired, ∼  1 % ended up in the TPC (including export), and 5–25 % was added to the DOC pool. During phase II, the respiration loss increased to ∼  100 % of GPP at the ambient CO2 concentration, whereas respiration was lower (85–95 % of GPP) in the highest CO2 treatment. Bacterial production was ∼  30 % lower, on average, at the highest CO2 concentration than in the controls during phases II and III. This resulted in a higher accumulation of DOC and lower reduction in the TPC pool in the elevated CO2 treatments at the end of phase II extending throughout phase III. The “extra” organic carbon at high CO2 remained fixed in an increasing biomass of small-sized plankton and in the DOC pool, and did not transfer into large, sinking aggregates. Our results revealed a clear effect of increasing CO2 on the carbon budget and mineralization, in particular under nutrient limited conditions. Lower carbon loss processes (respiration and bacterial remineralization) at elevated CO2 levels resulted in higher TPC and DOC pools than ambient CO2 concentration. These results highlight the importance of addressing not only net changes in carbon standing stocks but also carbon fluxes and budgets to better disentangle the effects of ocean acidification.

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Effects of ocean acidification on pelagic carbon fluxes in a mesocosm experiment

10.5194/bg-2016-56 ◽

2016 ◽

Cited By ~ 1

Author(s):

Kristian Spilling ◽

Kai G. Schulz ◽

Allanah J. Paul ◽

Tim Boxhammer ◽

Eric P. Achterberg ◽

...

Keyword(s):

Organic Carbon ◽

Primary Production ◽

Ocean Acidification ◽

Bacterial Production ◽

Co2 Concentration ◽

Carbon Fluxes ◽

Co2 Levels ◽

Standing Stocks ◽

Co2 Treatment ◽

Ambient Co2

Abstract. About a quarter of anthropogenic CO2 emissions are currently taken up by the oceans decreasing seawater pH. We performed a mesocosm experiment in the Baltic Sea in order to investigate the consequences of increasing CO2 levels on pelagic carbon fluxes. A gradient of different CO2 scenarios, ranging from ambient (~ 370 µatm) to high (~ 1200 µatm), were set up in mesocosm bags (~ 55 m3). We determined standing stocks and temporal changes of total particulate carbon (TPC), dissolved organic (DOC), dissolved inorganic (DIC) and particulate organic carbon (POC) of specific plankton groups. We also measured carbon flux via CO2 exchange with the atmosphere and sedimentation (export); and biological rate measurements of primary production, bacterial production and total respiration. The experiment lasted for 44 days and was divided into three different phases (I: t0–t16; II: t17–t30; III: t31–t43). Pools of TPC, DOC and DIC were approximately 420, 7200 and 25 200 mmol C m−2 at the start of the experiment, and the initial CO2 additions increased the DIC pool by ~ 7 % in the highest CO2 treatment. Overall, there was a decrease in TPC and increase of DOC over the course of the experiment. The decrease in TPC was lower, and increase in DOC higher, in treatments with added CO2. During Phase I the estimated gross primary production (GPP) was ~ 100 mmol C fixed m−2 d−1; from which 75–95 % were respired, ~ 1 % ended up in the TPC (including export) and 5–25 % added to the DOC pool. During Phase II, the respiration loss increased to ~ 100 % of GPP at the ambient CO2 concentration, whereas respiration was lower (85–95 % of GPP) in the highest CO2 treatment. Bacterial production was ~ 30 % lower, on average, at the highest CO2 concentration compared with the controls during Phases II and III. This resulted in a higher accumulation DOC standing stock and lower reduction in TPC in the elevated CO2 treatments at the end of Phase II extending throughout Phase III. The "extra" organic carbon at high CO2 remained fixed in an increasing biomass of small-sized plankton and in the DOC pool, and did not transferred into large, sinking aggregates. Our results revealed a clear effect of increasing CO2 on carbon production and mineralization, in particular under nutrient limited conditions. Lower carbon loss processes (respiration and bacterial remineralization) at elevated CO2 levels resulted in higher TPC and DOC pools compared with the ambient CO2 concentration. These results highlight the importance to address not only net changes in carbon standing stocks, but also carbon fluxes and budgets to better disentangle the effects of ocean acidification.

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Acidification can directly affect olfaction in marine organisms

Journal of Experimental Biology ◽

10.1242/jeb.237941 ◽

2021 ◽

Vol 224 (14) ◽

Author(s):

Cosima S. Porteus ◽

Christina C. Roggatz ◽

Zelia Velez ◽

Jörg D. Hardege ◽

Peter C. Hubbard

Keyword(s):

Olfactory Bulb ◽

Ocean Acidification ◽

Marine Fish ◽

Low Ph ◽

Marine Organisms ◽

Gamma Aminobutyric Acid ◽

Ion Distribution ◽

Gabaergic Neurotransmission ◽

High Co2 ◽

Olfactory Bulb Neurons

ABSTRACT In the past decade, many studies have investigated the effects of low pH/high CO2 as a proxy for ocean acidification on olfactory-mediated behaviours of marine organisms. The effects of ocean acidification on the behaviour of fish vary from very large to none at all, and most of the maladaptive behaviours observed have been attributed to changes in acid–base regulation, leading to changes in ion distribution over neural membranes, and consequently affecting the functioning of gamma-aminobutyric acid-mediated (GABAergic) neurotransmission. Here, we highlight a possible additional mechanism by which ocean acidification might directly affect olfaction in marine fish and invertebrates. We propose that a decrease in pH can directly affect the protonation, and thereby, 3D conformation and charge distribution of odorants and/or their receptors in the olfactory organs of aquatic animals. This can sometimes enhance signalling, but most of the time the affinity of odorants for their receptors is reduced in high CO2/low pH; therefore, the activity of olfactory receptor neurons decreases as measured using electrophysiology. The reduced signal reception would translate into reduced activation of the olfactory bulb neurons, which are responsible for processing olfactory information in the brain. Over longer exposures of days to weeks, changes in gene expression in the olfactory receptors and olfactory bulb neurons cause these neurons to become less active, exacerbating the problem. A change in olfactory system functioning leads to inappropriate behavioural responses to odorants. We discuss gaps in the literature and suggest some changes to experimental design in order to improve our understanding of the underlying mechanisms and their effects on the associated behaviours to resolve some current controversy in the field regarding the extent of the effects of ocean acidification on marine fish.

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