Physiological responses to temperature and ocean acidification in tropical fleshy macroalgae with varying affinities for inorganic carbon

2020 ◽  
Author(s):  
Maureen Ho ◽  
James McBroom ◽  
Ellie Bergstrom ◽  
Guillermo Diaz-Pulido
Keyword(s):  
Ocean Acidification ◽  
Inorganic Carbon ◽  
Environmental Changes ◽  
Dissolved Inorganic Carbon ◽  
Physiological Responses ◽  
Marine Macroalgae ◽  
Interactive Effects ◽  
Carbon Uptake ◽  
Metabolic Rates ◽  
Δ13c Values

Abstract Marine macroalgae have variable carbon-uptake strategies that complicate predicting responses to environmental changes. In seawater, dissolved inorganic carbon availability can affect the underlying physiological mechanisms influencing carbon uptake. We tested the interactive effects of ocean acidification (OA) and warming on two HCO3−-users (Lobophora sp. and Amansia rhodantha), a predominately CO2-user (Avrainvillea nigricans), and a sole CO2-user (Plocamium hamatum) in the Great Barrier Reef, Australia. We examined metabolic rates, growth, and carbon isotope values (δ13C) in algae at 26, 28, or 30°C under ambient or elevated pCO2 (∼1000 µatm). Under OA, δ13C values for the HCO3−-users decreased, indicating less reliance on HCO3−, while δ13C values for CO2-users were unaffected. Both HCO3−-users decreased in growth across temperatures under ambient pCO2, but this negative effect was alleviated by OA at 30°C. A. nigricans lost biomass across all treatments and P. hamatum was most sensitive, with reduced survival in all physiological responses. Metabolic rates varied greatly to interacting temperature and OA and indicated a decoupling between the relationship of photosynthesis and growth. Furthermore, our findings suggest HCO3−-users are more responsive to future CO2 changes, and highlight examining carbon physiology to infer potential responses to interacting environmental stressors.

scholarly journals Mechanism of O and C isotope fractionation in magnesian calcite skeletons of <i>Octocorallia</i> corals and an implication on their calcification response to ocean acidification

2015 ◽  
Vol 12 (1) ◽  
pp. 389-412 ◽  
Author(s):  
T. Yoshimura ◽  
A. Suzuki ◽  
N. Iwasaki
Keyword(s):  
Ocean Acidification ◽  
Isotope Fractionation ◽  
Inorganic Carbon ◽  
Environmental Changes ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Ambient Seawater ◽  
Large Variability ◽  
Coral Skeletons ◽  
Δ18o And Δ13c

Abstract. Coral calcification is strongly dependent on both the pH and the dissolved inorganic carbon (DIC) of the calcifying fluid. Skeletal oxygen and carbon isotope fractionation of high-Mg calcite skeletons of \\textit{Octocorallia} corals directly record the biological manipulation on sources of DIC in response to environmental changes. The coral skeletons were enriched in light isotopes (16O and 12C) relative to the expected values based on habitat environmental parameters and Mg/Ca of the skeletons. The differences between the expected and observed values ranged from −4.66 to −1.53 for δ18O and from −7.34 to −1.75 for δ13C. The large variability cannot be explained by the ambient environment, the contribution of metabolic carbon, or the precipitation rate of the skeleton. Therefore, the most plausible explanation for the observed O and C isotope differences in high-Mg calcite coral skeletons is the existence of two carbon sources, aqueous carbon dioxide in the calcifying fluid and dissolved inorganic carbon in seawater. Positive correlations of B/Ca with δ18O and δ13C suggest that skeletal isotopic compositions are enriched in light isotopes when conditions are less alkaline. Therefore, the relative contribution of isotopically heavy DIC from seawater through the skeleton and pericellular channels decreases under the reduced pH of the extracytoplasmic calcifying fluid. Our data suggest an even stronger biological effect under lower pH. Skeletal δ18O and δ13C values record the response of the sources of DIC in the coral calcifying fluids to ambient seawater pH. These changes give insight into how ocean acidification impacts the physiological mechanisms as well as the pH offset between calcifying fluid and seawater in response to ocean acidification.

scholarly journals Lake water dissolved inorganic carbon dynamics revealed from monthly measurements of radiocarbon in the Fuji Five Lakes, Japan

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Kosuke Ota ◽  
Yusuke Yokoyama ◽  
Yosuke Miyairi ◽  
Shinya Yamamoto ◽  
Toshihiro Miyajima
Keyword(s):  
Lake Water ◽  
Inorganic Carbon ◽  
Environmental Changes ◽  
Dissolved Inorganic Carbon ◽  
Anthropogenic Activities ◽  
Aquatic Organisms ◽  
Human Society ◽  
History Of ◽  
Lake Waters ◽  
Reservoir Age

Lakes are sensitive recorders of anthropogenic activities, as human society often develops in their vicinity. Lake sediments thus have been widely used to reconstruct the history of environmental changes in the past, anthropogenic, or otherwise, and radiocarbon dating provides chronological control of the samples. However, specific values of radiocarbon in different carbon reservoirs due to the different pathways of radiocarbon from the upper atmosphere to the lake, called the radiocarbon reservoir age, is always difficult to evaluate because of dynamic processes in and around lakes. There are few systematic studies on radiocarbon reservoir ages for lakes owing to the complex radiocarbon transfer processes for lakes. Here, we investigate lake waters of the Fuji Five Lakes with monthly monitoring of the radiocarbon reservoir effects. Radiocarbon from dissolved inorganic carbon (DIC) for groundwater and river water is also measured, with resulting concentrations (Δ14C) at their lowest at Lake Kawaguchi in August 2018 (–122.4 ± 3.2‰), and at their highest at Lake Motosu in January 2019 (–22.4 ± 2.5‰), despite a distance of 25 km. However, winter values in both lakes show similar trends of rising Δ14C (about 20‰). Our lake water DIC Δ14C results are compared to previously published records obtained from sediments in Lake Motosu and Lake Kawaguchi. These suggest that total organic carbon and compound-specific radiocarbon found in sediments are heavily influenced by summer blooms of aquatic organisms that fix DIC in water. Thus, future studies to conduct similar analyses at the various lakes would be able to provide further insights into the carbon cycle around inland water, namely understanding the nature of radiocarbon reservoir ages.

scholarly journals Reviews and Syntheses: Responses of coccolithophores to ocean acidification: a meta-analysis

2015 ◽  
Vol 12 (6) ◽  
pp. 1671-1682 ◽  
Author(s):  
J. Meyer ◽  
U. Riebesell
Keyword(s):  
Ocean Acidification ◽  
Dissolved Inorganic Carbon ◽  
Meta Analysis ◽  
Physiological Responses ◽  
Total Alkalinity ◽  
Adaptive Responses ◽  
Negative Effects ◽  
Ecological Fitness ◽  
Negative Effect ◽  
Gephyrocapsa Oceanica

Abstract. Concerning their sensitivity to ocean acidification, coccolithophores, a group of calcifying single-celled phytoplankton, are one of the best-studied groups of marine organisms. However, in spite of the large number of studies investigating coccolithophore physiological responses to ocean acidification, uncertainties still remain due to variable and partly contradictory results. In the present study we have used all existing data in a meta-analysis to estimate the effect size of future pCO2 changes on the rates of calcification and photosynthesis and the ratio of particulate inorganic to organic carbon (PIC / POC) in different coccolithophore species. Our results indicate that ocean acidification has a negative effect on calcification and the cellular PIC / POC ratio in the two most abundant coccolithophore species: Emiliania huxleyi and Gephyrocapsa oceanica. In contrast, the more heavily calcified species Coccolithus braarudii did not show a distinct response when exposed to elevated pCO2/reduced pH. Photosynthesis in Gephyrocapsa oceanica was positively affected by high CO2, while no effect was observed for the other coccolithophore species. There was no indication that the method of carbonate chemistry manipulation was responsible for the inconsistent results regarding observed responses in calcification and the PIC / POC ratio. The perturbation method, however, appears to affect photosynthesis, as responses varied significantly between total alkalinity (TA) and dissolved inorganic carbon (DIC) manipulations. These results emphasize that coccolithophore species respond differently to ocean acidification, both in terms of calcification and photosynthesis. Where negative effects occur, they become evident at CO2 levels in the range projected for this century in the case of unabated CO2 emissions. As the data sets used in this meta-analysis do not account for adaptive responses, ecological fitness and ecosystem interactions, the question remains as to how these physiological responses play out in the natural environment.

NZOA-ON: the New Zealand Ocean Acidification Observing Network

2020 ◽  
Vol 71 (3) ◽  
pp. 281 ◽  
Author(s):  
J. M. Vance ◽  
K. I. Currie ◽  
C. S. Law ◽  
J. Murdoch ◽  
J. Zeldis
Keyword(s):  
New Zealand ◽  
Ocean Acidification ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Total Alkalinity ◽  
Grass Roots ◽  
The Past ◽  
Field Samples ◽  
The University ◽  
Global Initiatives

A national observing network has been operating over the past 4 years to inform the scientific and economic challenges of ocean acidification (OA) facing New Zealand. The New Zealand Ocean Acidification Observing Network (NZOA-ON) consists of 12 sites across varied coastal ecosystems. These ecosystems range from oligotrophic ocean-dominated systems to eutrophic river-dominated systems, with sites that are pristine or affected by agriculture and urbanisation. Fortnightly measurements of total alkalinity and dissolved inorganic carbon provide the baseline of carbonate chemistry in these varied ecosystems and will facilitate detection of future changes, as well as providing a present-day baseline. The National Institute of Water and Atmospheric Research and the University of Otago have developed a ‘grass-roots’ sampling program, providing training and equipment that enable sampling partners to collect field samples for analyses at a central laboratory. NZOA-ON leverages existing infrastructure and partnerships to maximise data captured for understanding the drivers of chemical changes associated with OA and ecological responses. NZOA-ON coordinates with and contributes to global initiatives to understand and mitigate the broader impacts of OA. A description of NZOA-ON is presented with preliminary analyses and comparison of data from different sites after the first 4 years of the network.

Ocean acidification as a multiple driver: how interactions between changing seawater carbonate parameters affect marine life

2020 ◽  
Vol 71 (3) ◽  
pp. 263 ◽  
Author(s):  
Catriona L. Hurd ◽  
John Beardall ◽  
Steeve Comeau ◽  
Christopher E. Cornwall ◽  
Jonathan N Havenhand ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Multiple Stressors ◽  
Rapid Expansion ◽  
Coralline Algae ◽  
Carbonate System ◽  
Saturation State ◽  
Marine Life ◽  
Key Terms

‘Multiple drivers’ (also termed ‘multiple stressors’) is the term used to describe the cumulative effects of multiple environmental factors on organisms or ecosystems. Here, we consider ocean acidification as a multiple driver because many inorganic carbon parameters are changing simultaneously, including total dissolved inorganic carbon, CO2, HCO3–, CO32–, H+ and CaCO3 saturation state. With the rapid expansion of ocean acidification research has come a greater understanding of the complexity and intricacies of how these simultaneous changes to the seawater carbonate system are affecting marine life. We start by clarifying key terms used by chemists and biologists to describe the changing seawater inorganic carbon system. Then, using key groups of non-calcifying (fish, seaweeds, diatoms) and calcifying (coralline algae, coccolithophores, corals, molluscs) organisms, we consider how various physiological processes are affected by different components of the carbonate system.

scholarly journals Development of a Biogeochemical and Carbon Model Related to Ocean Acidification Indices with an Operational Ocean Model Product in the North Western Pacific

2019 ◽  
Vol 11 (9) ◽  
pp. 2677 ◽  
Author(s):  
Miho Ishizu ◽  
Yasumasa Miyazawa ◽  
Tomohiko Tsunoda ◽  
Xinyu Guo
Keyword(s):  
Ocean Acidification ◽  
General Circulation ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Ocean Model ◽  
Western Pacific ◽  
Total Alkalinity ◽  
The North ◽  
North Western ◽  
North Western Pacific

We developed a biogeochemical and carbon model (JCOPE_EC) coupled with an operational ocean model for the North Western Pacific. JCOPE_EC represents ocean acidification indices on the background of the risks due to ocean acidification and our model experiences. It is an off-line tracer model driven by a high-resolution regional ocean general circulation model (JCOPE2M). The results showed that the model adequately reproduced the general patterns in the observed data, including the seasonal variability of chlorophyll-a, dissolved inorganic nitrogen/phosphorus, dissolved inorganic carbon, and total alkalinity. We provide an overview of this system and the results of the model validation based on the available observed data. Sensitivity analysis using fixed values for temperature, salinity, dissolved inorganic carbon and total alkalinity helped us identify which variables contributed most to seasonal variations in the ocean acidification indices, pH and Ωarg. The seasonal variation in the pHinsitu was governed mainly by balances of the change in temperature and dissolved inorganic carbon. The seasonal increase in Ωarg from winter to summer was governed mainly by dissolved inorganic carbon levels.

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