high pco2
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Author(s):  
Rita A. Costa ◽  
Zélia Velez ◽  
Peter C. Hubbard

Exposure to high PCO2/low pH seawater induces behavioural alterations in fish; a possible explanation for this is a reversal of Cl−/HCO3− currents through GABAA receptors (the GABAA receptor theory). However, the main evidence for this is that gabazine, a GABAA receptor antagonist, reverses these effects when applied to the water, assuming that exposure to systems other than the CNS would be without effect. Here, we show the expression of both metabotropic and ionotropic GABA receptors, and the presence of GABAA receptor protein, in the olfactory epithelium (OE) of gilthead seabream. Furthermore, exposure of the OE to muscimol (a specific GABAA receptor agonist) increases or decreases the apparent olfactory sensitivity to some odorants. Thus, although the exact function of GABAA receptors in the OE is not yet clear, this may complicate the interpretation of studies wherein water-borne gabazine is used to reverse the effects of high CO2 levels on olfactory-driven behaviour in fish.


Author(s):  
Clara Coll-Lladó ◽  
Felix Mittermayer ◽  
Paul Brian Webb ◽  
Nicola Allison ◽  
Catriona Clemmesen ◽  
...  

AbstractTo date the study of ocean acidification on fish otolith formation has been mainly focused on larval and juvenile stages. In the present pilot study, wild-captured adult Atlantic cod (Gadus morhua) were exposed to two different levels of pCO2, 422µatm (ambient, low pCO2) or 1091µatm (high pCO2), for a period of 30 weeks (from mid-October to early April 2014–2015) in order to study the effects on otolith size, shape and CaCO3 crystallization amongst other biological parameters. We found that otoliths from cod exposed to high pCO2 were slightly smaller (− 3.4% in length; − 3.3% in perimeter), rounder (− 2.9% circularity and + 4% roundness) but heavier (+ 5%) than the low pCO2 group. Interestingly, there were different effects in males and females; for instance, male cods exposed to high pCO2 exhibited significant changes in circularity (− 3%) and roundness (+ 4%) compared to the low pCO2 males, but without significant changes on otolith dimensions, while females exposed to high pCO2 had smaller otoliths as shown for length (− 5.6%), width (− 2%), perimeter (− 3.5%) and area (− 4.8%). Furthermore, while the majority of the otoliths analysed showed normal aragonite deposition, 10% of fish exposed to 1091µatm of pCO2 had an abnormal accretion of calcite, suggesting a shift on calcium carbonate polymorph crystallization in some individuals under high pCO2 conditions. Our preliminary results indicate that high levels of pCO2 in adult Atlantic cod might affect otolith growth in a gender-specific way. Our findings reveal that otoliths from adult cod are affected by ocean acidification, and we believe that the present study will prompt further research into this currently under-explored area.


2021 ◽  
Vol 18 (18) ◽  
pp. 5117-5140
Author(s):  
Federica Maggioni ◽  
Mireille Pujo-Pay ◽  
Jérome Aucan ◽  
Carlo Cerrano ◽  
Barbara Calcinai ◽  
...  

Abstract. According to current experimental evidence, coral reefs could disappear within the century if CO2 emissions remain unabated. However, recent discoveries of diverse and high cover reefs that already live under extreme conditions suggest that some corals might thrive well under hot, high-pCO2, and deoxygenated seawater. Volcanic CO2 vents, semi-enclosed lagoons, and mangrove estuaries are unique study sites where one or more ecologically relevant parameters for life in the oceans are close to or even worse than currently projected for the year 2100. Although they do not perfectly mimic future conditions, these natural laboratories offer unique opportunities to explore the mechanisms that reef species could use to keep pace with climate change. To achieve this, it is essential to characterize their environment as a whole and accurately consider all possible environmental factors that may differ from what is expected in the future, possibly altering the ecosystem response. This study focuses on the semi-enclosed lagoon of Bouraké (New Caledonia, southwest Pacific Ocean) where a healthy reef ecosystem thrives in warm, acidified, and deoxygenated water. We used a multi-scale approach to characterize the main physical-chemical parameters and mapped the benthic community composition (i.e., corals, sponges, and macroalgae). The data revealed that most physical and chemical parameters are regulated by the tide, strongly fluctuate three to four times a day, and are entirely predictable. The seawater pH and dissolved oxygen decrease during falling tide and reach extreme low values at low tide (7.2 pHT and 1.9 mg O2 L−1 at Bouraké vs. 7.9 pHT and 5.5 mg O2 L−1 at reference reefs). Dissolved oxygen, temperature, and pH fluctuate according to the tide by up to 4.91 mg O2 L−1, 6.50 ∘C, and 0.69 pHT units on a single day. Furthermore, the concentration of most of the chemical parameters was 1 to 5 times higher at the Bouraké lagoon, particularly for organic and inorganic carbon and nitrogen but also for some nutrients, notably silicates. Surprisingly, despite extreme environmental conditions and altered seawater chemical composition measured at Bouraké, our results reveal a diverse and high cover community of macroalgae, sponges, and corals accounting for 28, 11, and 66 species, respectively. Both environmental variability and nutrient imbalance might contribute to their survival under such extreme environmental conditions. We describe the natural dynamics of the Bouraké ecosystem and its relevance as a natural laboratory to investigate the benthic organism's adaptive responses to multiple extreme environmental conditions.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Liyenne Cavalheiro ◽  
Thomas Wagner ◽  
Sebastian Steinig ◽  
Cinzia Bottini ◽  
Wolf Dummann ◽  
...  

AbstractThe Weissert Event ~133 million years ago marked a profound global cooling that punctuated the Early Cretaceous greenhouse. We present modelling, high-resolution bulk organic carbon isotopes and chronostratigraphically calibrated sea surface temperature (SSTs) based on an organic paleothermometer (the TEX86 proxy), which capture the Weissert Event in the semi-enclosed Weddell Sea basin, offshore Antarctica (paleolatitude ~54 °S; paleowater depth ~500 meters). We document a ~3–4 °C drop in SST coinciding with the Weissert cold end, and converge the Weddell Sea data, climate simulations and available worldwide multi-proxy based temperature data towards one unifying solution providing a best-fit between all lines of evidence. The outcome confirms a 3.0 °C ( ±1.7 °C) global mean surface cooling across the Weissert Event, which translates into a ~40% drop in atmospheric pCO2 over a period of ~700 thousand years. Consistent with geologic evidence, this pCO2 drop favoured the potential build-up of local polar ice.


Metabolites ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 584
Author(s):  
Fanny Noisette ◽  
Piero Calosi ◽  
Diana Madeira ◽  
Mathilde Chemel ◽  
Kayla Menu-Courey ◽  
...  

Bentho-pelagic life cycles are the dominant reproductive strategy in marine invertebrates, providing great dispersal ability, access to different resources, and the opportunity to settle in suitable habitats upon the trigger of environmental cues at key developmental moments. However, free-dispersing larvae can be highly sensitive to environmental changes. Among these, the magnitude and the occurrence of elevated carbon dioxide (CO2) concentrations in oceanic habitats is predicted to exacerbate over the next decades, particularly in coastal areas, reaching levels beyond those historically experienced by most marine organisms. Here, we aimed to determine the sensitivity to elevated pCO2 of successive life stages of a marine invertebrate species with a bentho-pelagic life cycle, exposed continuously during its early ontogeny, whilst providing in-depth insights on their metabolic responses. We selected, as an ideal study species, the American lobster Homarus americanus, and investigated life history traits, whole-organism physiology, and metabolomic fingerprints from larval stage I to juvenile stage V exposed to different pCO2 levels. Current and future ocean acidification scenarios were tested, as well as extreme high pCO2/low pH conditions that are predicted to occur in coastal benthic habitats and with leakages from underwater carbon capture storage (CCS) sites. Larvae demonstrated greater tolerance to elevated pCO2, showing no significant changes in survival, developmental time, morphology, and mineralisation, although they underwent intense metabolomic reprogramming. Conversely, juveniles showed the inverse pattern, with a reduction in survival and an increase in development time at the highest pCO2 levels tested, with no indication of metabolomic reprogramming. Metabolomic sensitivity to elevated pCO2 increased until metamorphosis (between larval and juvenile stages) and decreased afterward, suggesting this transition as a metabolic keystone for marine invertebrates with complex life cycles.


2021 ◽  
Author(s):  
Peihong Jin ◽  
Mingzheng Zhang ◽  
Xiangtong Lei ◽  
Baoxia Du ◽  
Junling Dong ◽  
...  

Abstract. In recent decades, several proxies have been developed to reconstruct atmospheric paleo-CO2 concentrations (pCO2). The confidence in paleo-CO2 estimates can be increased by comparing results from multiple proxies with multiple species at a single site. Here we present a new pCO2 record for the Hauterivian–Barremian using three methods based on two fossil coniferous species (Cupressinocladus sp. and Brachyphyllum obtusum) collected from Laiyang Basin, eastern China. The pCO2 values were approximately 579–663 ppmv (recent standardization) and 966–1106 ppmv (carboniferous standardization) based on the stomatal ratio (SR)-based method, and about 472–525 ppmv based on the mechanistic model. Both of these two methods were highly coincident with other SR-based and geochemical reconstructions for the early stage of the Early Cretaceous. The pCO2 value estimated using the carbon isotopes model was approximately 472–525 ppmv, which is generally lower than the pCO2 valueestimated using the other methods. The mechanistic model may be widely applied to more fossil taxa than the SR-based method and retains sensitivity at high pCO2. Furthermore, by comparing with other pCO2 records and Weissert event in the Early Cretaceous, the pCO2 values obtained from this study indicate a relatively low atmospheric CO2 concentration during the Hauterivian–Barremian, and reflect the cooling event in the last stage of the Weissert event.


2021 ◽  
Vol 61 (4) ◽  
pp. 223-8
Author(s):  
Reby Kusumajaya ◽  
Najib Advani ◽  
Piprim B. Yanuarso ◽  
Zulham Effendy

Background Corrective cardiac surgery is the standard management for complex congenital heart disease. Cardiopulmonary bypass surgery and post-surgical intensive care may lead to low cardiac output syndrome (LCOS), as a major complication after open heart surgery.  To diagnose early LCOS, lactate level, pCO2 gap, and mixed venous oxygen saturation (SvO2) are parameters reported to have correlations with decreased cardiac output, morbidity, and post-cardiac surgery mortality. Objective To determine the usefulness of lactate level, pCO2 gap (arterial-vein), and SvO2 for early detection of LCOS in children post-open heart surgery. Methods This prospective cohort study was done from August to October 2017 in the ICU of the Integrated Cardiac Center, Dr. Cipto Mangunkusumo Hospital, Jakarta. Subjects were pediatric patients who underwent cardiac surgery. After surgery, patients underwent monitoring in the ICU for clinical signs of LCOS and examinations for lactate levels, pCO2 gap, and SvO2 at 15 minutes, 4 hours and 8 hours. Results Thirty-three open heart surgery patients were the subjects. Lactate level at 4 hours and 8 hours post-operative were significantly higher in the LCOS group compared to non-LCOS group. For the pCO2 gap, only the 4-hour post-operative results were significantly higher in LCOS group compared to non-LCOS groups. In addition, only SvO2 at 4 hours after surgery was significantly lower in LCOS group compared to non-LCOS group. Conclusion Elevated lactate, high pCO2 gap, as well as decreased SvO2 at 4 hours post-operatively are the most reliable markers of LCOS after pediatric open heart surgery.


2021 ◽  
pp. 393-396
Author(s):  
Paul Shand ◽  
W.Mike Edmunds ◽  
Valentina A. Chudaeva ◽  
Tatiyana N. Lutsenko ◽  
Oleg V. Chudaev ◽  
...  

Diversity ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 311
Author(s):  
Alessandra Barruffo ◽  
Laura Ciaralli ◽  
Giandomenico Ardizzone ◽  
Maria Cristina Gambi ◽  
Edoardo Casoli

Ocean acidification has been broadly recognised to have effects on the structure and functioning of marine benthic communities. The selection of tolerant or vulnerable species can also occur during settlement phases, especially for calcifying organisms which are more vulnerable to low pH–high pCO2 conditions. Here, we use three natural CO2 vents (Castello Aragonese north and south sides, and Vullatura, Ischia, Italy) to assess the effect of a decrease of seawater pH on the settlement of Mollusca in Posidonia oceanica meadows, and to test the possible buffering effect provided by the seagrass. Artificial collectors were installed and collected after 33 days, during April–May 2019, in three different microhabitats within the meadow (canopy, bottom/rhizome level, and dead matte without plant cover), following a pH decreasing gradient from an extremely low pH zone (pH < 7.4), to ambient pH conditions (pH = 8.10). A total of 4659 specimens of Mollusca, belonging to 57 different taxa, were collected. The number of taxa was lower in low and extremely low pH conditions. Reduced mollusc assemblages were reported at the acidified stations, where few taxa accounted for a high number of individuals. Multivariate analyses revealed significant differences in mollusc assemblages among pH conditions, microhabitat, and the interaction of these two factors. Acanthocardia echinata, Alvania lineata, Alvania sp. juv, Eatonina fulgida, Hiatella arctica, Mytilys galloprovincialis, Musculus subpictus, Phorcus sp. juv, and Rissoa variabilis were the species mostly found in low and extremely low pH stations, and were all relatively robust to acidified conditions. Samples placed on the dead matte under acidified conditions at the Vullatura vent showed lower diversity and abundances if compared to canopy and bottom/rhizome samples, suggesting a possible buffering role of the Posidonia on mollusc settlement. Our study provides new evidence of shifts in marine benthic communities due to ocean acidification and evidence of how P. oceanica meadows could mitigate its effects on associated biota in light of future climate change.


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