Ambient CO2 Levels Research Articles

Effects of short-term mild hypercapnia during head-down tilt on intracranial pressure and ocular structures in healthy human subjects.

Many astronauts experience ocular structural and functional changes during long‐duration spaceflight, including choroidal folds, optic disc edema, globe flattening, optic nerve sheath diameter (ONSD) distension, retinal nerve fiber layer thickening, and decreased visual acuity. The leading hypothesis suggests that weightlessness‐induced cephalad fluid shifts increase intracranial pressure (ICP), which contributes to the ocular structural changes, but elevated ambient CO 2 levels on the International Space Station may also be a factor. We used the spaceflight analog of 6° head‐down tilt (HDT) to investigate possible mechanisms for ocular changes in eight male subjects during three 1‐h conditions: Seated, HDT, and HDT with 1% inspired CO 2 (HDT + CO 2). Noninvasive ICP, intraocular pressure (IOP), translaminar pressure difference (TLPD = IOP‐ICP), cerebral and ocular ultrasound, and optical coherence tomography (OCT) scans of the macula and the optic disc were obtained. Analysis of one‐carbon pathway genetics previously associated with spaceflight‐induced ocular changes was conducted. Relative to Seated, IOP and ICP increased and TLPD decreased during HDT. During HDT + CO 2 IOP increased relative to HDT, but there was no significant difference in TLPD between the HDT conditions. ONSD and subfoveal choroidal thickness increased during HDT relative to Seated, but there was no difference between HDT and HDT + CO 2. Visual acuity and ocular structures assessed with OCT imaging did not change across conditions. Genetic polymorphisms were associated with differences in IOP, ICP, and end‐tidal PCO 2. In conclusion, acute exposure to mild hypercapnia during HDT did not augment cardiovascular outcomes, ICP, or TLPD relative to the HDT condition.

Effects of elevated CO2 on the fitness and potential population damage of Helicoverpa armigera based on two-sex life table

We evaluated the direct effects of three different atmospheric CO2 concentrations (380 ppm, 550 ppm and 750 ppm) on the population parameters of the cotton bollworm, Helicoverpa armigera fed an artificial diet. The life history and fitness of H. armigera were analyzed using an age-stage, two-sex life table. Our results showed significantly longer larval durations and lower female pupal weight under elevated CO2 than under ambient CO2. Additionally, the fecundity of H. armigera was lower under elevated CO2 than under ambient CO2. H. armigera reared under elevated CO2 conditions showed lower intrinsic and finite rates of increase but higher net consumption and finite consumption rates than H. armigera reared under ambient CO2 conditions. According to population projections, a much smaller total population size and reduced consumption capacities would be expected in an elevated CO2 atmosphere due to higher mortality and lower growth rate compared with ambient CO2 levels. These results indicate that the fitness of and potential damage caused by H. armigera would be affected by increased CO2 relative to ambient CO2 concentrations. Additional studies on the long-term direct and indirect effects of elevated CO2 levels on H. armigera are still needed.

Elevated carbon dioxide level along with phosphorus application and cyanobacterial inoculation enhances nitrogen fixation and uptake in cowpea crop

ABSTRACTClimate change, as a result of increase in the concentration of greenhouse gases, influences growth and productivity of leguminous crops. A study was carried out to analyse the impacts of elevated carbon dioxide (CO2) and cyanobacterial inoculation on growth, N2 fixation and N availability and uptake in cowpea crop, under different doses of phosphorus. Cowpea crop was grown under ambient (400 µmol mol−1) and elevated (550 ± 20 µmol mol−1) CO2 levels using Free-Air Carbon dioxide Enrichment facility. Elevated CO2 level increased chlorophyll content in leaves, improved nodulation and nitrogen fixation by the crop. Increase in P dose up to 16 mg kg−1 soil enhanced nodule development and N2 fixation under high CO2 condition. Cyanobacterial inoculation increased nodule weight, leghaemoglobin content in nodules and total nitrogenase activity. Although nitrogen concentration in cowpea seeds decreased in high CO2 treatment, higher N uptake was recorded. Under elevated CO2 condition, cyanobacterial inoculation and higher P doses led to enhanced root growth and N2 fixation and availability of soil nitrogen. The study illustrated the synergistic effect of high CO2 and cyanobacterial inoculation in enhancing crop growth and availability of soil N, mediated by biological N2 fixation in cowpea under different levels of P.

An Ocean Acidification Acclimatised Green Tide Alga Is Robust to Changes of Seawater Carbon Chemistry but Vulnerable to Light Stress.

Ulva is the dominant genus in the green tide events and is considered to have efficient CO2 concentrating mechanisms (CCMs). However, little is understood regarding the impacts of ocean acidification on the CCMs of Ulva and the consequences of thalli’s acclimation to ocean acidification in terms of responding to environmental factors. Here, we grew a cosmopolitan green alga, Ulva linza at ambient (LC) and elevated (HC) CO2 levels and investigated the alteration of CCMs in U. linza grown at HC and its responses to the changed seawater carbon chemistry and light intensity. The inhibitors experiment for photosynthetic inorganic carbon utilization demonstrated that acidic compartments, extracellular carbonic anhydrase (CA) and intracellular CA worked together in the thalli grown at LC and the acquisition of exogenous carbon source in the thalli could be attributed to the collaboration of acidic compartments and extracellular CA. Contrastingly, when U. linza was grown at HC, extracellular CA was completely inhibited, acidic compartments and intracellular CA were also down-regulated to different extents and thus the acquisition of exogenous carbon source solely relied on acidic compartments. The down-regulated CCMs in U. linza did not affect its responses to changes of seawater carbon chemistry but led to a decrease of net photosynthetic rate when thalli were exposed to increased light intensity. This decrease could be attributed to photodamage caused by the combination of the saved energy due to the down-regulated CCMs and high light intensity. Our findings suggest future ocean acidification might impose depressing effects on green tide events when combined with increased light exposure.

Elevated CO2 levels modify TiO2 nanoparticle effects on rice and soil microbial communities

Evidence suggests that CO2 modifies the behavior of nanomaterials. Thus, in a few decades, plants might be exposed to additional stress if atmospheric levels of CO2 and the environmental burden of nanomaterials increase at the current pace. Here, we used a full-size free-air CO2 enrichment (FACE) system in farm fields to investigate the effect of elevated CO2 levels on phytotoxicity and microbial toxicity of nTiO2 (0, 50, and 200mgkg−1) in a paddy soil system. Results show that nTiO2 did not induce visible signs of toxicity in rice plants cultivated at the ambient CO2 level (370μmolmol−1), but under the high CO2 concentration (570μmolmol−1) nTiO2 significantly reduced rice biomass by 17.9% and 22.1% at 50mgkg−1 and 200mgkg−1, respectively, and grain yield by 20.8% and 44.1% at 50mgkg−1 and 200mgkg−1, respectively. In addition, at the high CO2 concentration, nTiO2 at 200mgkg−1 increased accumulation of Ca, Mg, Mn, P, Zn, and Ti by 22.5%, 16.8%, 29.1%, 7.4%, 15.7% and 8.6%, respectively, but reduced fat and total sugar by 11.2% and 25.5%, respectively, in grains. Such conditions also changed the functional composition of soil microbial communities, alerting specific phyla of bacteria and the diversity and richness of protista. Overall, this study suggests that increases in CO2 levels would modify the effects of nTiO2 on the nutritional quality of crops and function of soil microbial communities, with unknown implications for future economics and human health.

Photosynthetic responses of the marine diatom Thalassiosira pseudonana to CO2-induced seawater acidification

Ocean acidification due to atmospheric CO2 rise is expected to influence marine phytoplankton. Diatoms are responsible for about 40% of the total primary production in the ocean. In order to investigate the physiological response of marine diatom Thalassiosira pseudonana to ocean acidification, we grew the cells under ambient CO2 level (380 µatm) versus the elevated CO2 level (800 µatm) at a light level of 180 µmol m−2 s−1 for 30 generations. Our results showed that the elevated CO2 concentration caused a decrease of the effective photochemical efficiency of PSII $$\left( {{{F_{{\text{v}}}^{\prime } } \mathord{\left/ {\vphantom {{F_{{\text{v}}}^{\prime } } {F_{{\text{m}}}^{\prime } }}} \right. \kern-\nulldelimiterspace} {F_{{\text{m}}}^{\prime } }}} \right)$$ and increase of the dark respiration in T. pseudonana. The intracellular carbonic anhydrase activity was suppressed and the photosynthetic affinity for CO2 was lowered in the high CO2-grown cells, reflecting a downregulation of the CO2 concentrating mechanism (CCM). PSI activity was enhanced to support an increase in ATP synthesis by cyclic electron transfer as required for transport of inorganic carbon and regulation of intracellular pH. The energetic benefit from the downregulation of CCM to growth as reported in other diatom species was not observed here in T. pseudonana.

Effects of elevated CO2 on predator avoidance behaviour by reef fishes is not altered by experimental test water.

Pioneering studies into the effects of elevated CO2 on the behaviour of reef fishes often tested high-CO2 reared fish using control water in the test arena. While subsequent studies using rearing treatment water (control or high CO2) in the test arena have confirmed the effects of high CO2 on a range of reef fish behaviours, a further investigation into the use of different test water in the experimental arena is warranted. Here, we used a fully factorial design to test the effect of rearing treatment water (control or high CO2) and experimental test water (control or high CO2) on antipredator responses of larval reef fishes. We tested antipredator behaviour in larval clownfish Amphiprion percula and ambon damselfish Pomacentrus amboinensis, two species that have been used in previous high CO2 experiments. Specifically, we tested if: (1) using control or high CO2 water in a two channel flume influenced the response of larval clownfish to predator odour; and (2) using control or high CO2 water in the test arena influenced the escape response of larval damselfish to a startle stimulus. Finally, (3) because the effects of high CO2 on fish behaviour appear to be caused by altered function of the GABA-A neurotransmitter we tested if antipredator behaviours were restored in clownfish treated with a GABA antagonist (gabazine) in high CO2 water. Larval clownfish reared from hatching in control water (496 µatm) strongly avoided predator cue whereas larval clownfish reared from hatching in high CO2 (1,022 µatm) were attracted to the predator cue, as has been reported in previous studies. There was no effect on fish responses of using either control or high CO2 water in the flume. Larval damselfish reared for four days in high CO2 (1,051 µatm) exhibited a slower response to a startle stimulus and slower escape speed compared with fish reared in control conditions (464 µatm). There was no effect of test water on escape responses. Treatment of high-CO2 reared clownfish with 4 mg l−1 gabazine in high CO2 seawater restored the normal response to predator odour, as has been previously reported with fish tested in control water. Our results show that using control water in the experimental trials did not influence the results of previous studies on antipredator behaviour of reef fishes and also supports the results of novel experiments conducted in natural reef habitat at ambient CO2 levels.

Elevated carbon dioxide has the potential to impact alarm cue responses in some freshwater fishes

Freshwater fish behaviors have the potential to be impacted by acidification due to increases in dissolved carbon dioxide (CO2). Recent work in the marine environment suggests that increased CO2 levels due to climate change can negatively affect fishes homing to natal environments, while also hindering their ability to detect predators and perform aerobically. The potential for elevated CO2 to have similar negative impacts on freshwater communities remains understudied. The objective of our study was to quantify the effects of elevated CO2 on the behaviors of fathead minnows (Pimephales promelas) and silver carp (Hypophthalmichthys molitrix) following exposure to conspecific skin extracts (alarm cues). In fathead minnows, their response to conspecific skin extracts was significantly impaired following exposure to elevated CO2 levels for at least 96 h, while silver carp behaviors were unaltered. However, fathead minnow behaviors did return to pre-CO2 exposure in high-CO2-exposed fish following 14 days of holding at ambient CO2 levels. Overall, this study suggests there may be potential impacts to freshwater fishes alarm cue behaviors following CO2 exposure, but these responses may be species-specific and will likely be abated should the CO2 stressor be removed.

Different strategies of metabolic regulation in cyanobacteria: from transcriptional to biochemical control.

Cyanobacteria Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803 show similar changes in the metabolic response to changed CO2 conditions but exhibit significant differences at the transcriptomic level. This study employs a systems biology approach to investigate the difference in metabolic regulation of Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803. Presented multi-level kinetic model for Synechocystis sp. PCC 6803 is a new approach integrating and analysing metabolomic, transcriptomic and fluxomics data obtained under high and ambient CO2 levels. Modelling analysis revealed that higher number of different isozymes in Synechocystis 6803 improves homeostatic stability of several metabolites, especially 3PGA by 275%, against changes in gene expression, compared to Synechococcus sp. PCC 7942. Furthermore, both cyanobacteria have the same amount of phosphoglycerate mutases but Synechocystis 6803 exhibits only ~20% differences in their mRNA levels after shifts from high to ambient CO2 level, in comparison to ~500% differences in the case of Synechococcus sp. PCC 7942. These and other data imply that the biochemical control dominates over transcriptional regulation in Synechocystis 6803 to acclimate central carbon metabolism in the environment of variable inorganic carbon availability without extra cost carried by large changes in the proteome.

Effect of elevated temperature and carbon dioxide levels on maydis leaf blight disease tolerance attributes in maize

In the present study, effect of elevated temperature and CO2 levels was assessed on maydis leaf blight (MLB) disease tolerance attributes of two maize genotypes PEHM 5 (moderately resistant) and CM 119 (highly susceptible). The maize genotypes were exposed to two CO2 levels: ambient (400ppm) and elevated (550±20ppm) and three temperature levels: ambient, 1.5°C higher than ambient and 3°C higher than ambient temperature throughout crop growth periods. Disease severity in CM 119 was higher than PEHM 5 in all treatments. The disease severity increased when temperature was increased 3°C higher than ambient temperature, but effect of temperature was subsided when CO2 concentration was increased from ambient to 550ppm level. Maximum (76.5% and 95.4%) and minimum (61.7% and 78.7%) disease severity in PEHM 5 and CM 119 was observed in 3°C elevated temperature and ambient CO2 level; and ambient temperature and elevated CO2 level, respectively. Six disease stress tolerance attributes were calculated based on yield under diseased (Ys) and without disease condition (Yp). Both Ys and Yp were positively correlated with disease stress tolerance index (DSTI), mean productivity (MP) and geometric mean productivity (GMP) and negatively correlated with disease tolerance (TOL) and disease stress susceptibility index (DSSI). Results showed that with the increase in ambient temperature, severity of MLB disease is likely to increase in future.

The effects of CO2 and nutrient fertilisation on the growth and temperature response of the mangrove Avicennia germinans.

In order to understand plant responses to both the widespread phenomenon of increased nutrient inputs to coastal zones and the concurrent rise in atmospheric CO2 concentrations, CO2-nutrient interactions need to be considered. In addition to its potential stimulating effect on photosynthesis and growth, elevated CO2 affects the temperature response of photosynthesis. The scarcity of experiments testing how elevated CO2 affects the temperature response of tropical trees hinders our ability to model future primary productivity. In a glasshouse study, we examined the effects of elevated CO2 (800ppm) and nutrient availability on seedlings of the widespread mangrove Avicennia germinans. We assessed photosynthetic performance, the temperature response of photosynthesis, seedling growth and biomass allocation. We found large synergistic gains in both growth (42%) and photosynthesis (115%) when seedlings grown under elevated CO2 were supplied with elevated nutrient concentrations relative to their ambient growing conditions. Growth was significantly enhanced under elevated CO2 only under high-nutrient conditions, mainly in above-ground tissues. Under low-nutrient conditions and elevated CO2, root volume was more than double that of seedlings grown under ambient CO2 levels. Elevated CO2 significantly increased the temperature optimum for photosynthesis by ca. 4°C. Rising CO2 concentrations are likely to have a significant positive effect on the growth rate of A. germinans over the next century, especially in areas where nutrient availability is high.

Coherent cavity-enhanced dual-comb spectroscopy.

Dual-comb spectroscopy allows for the rapid, multiplexed acquisition of high-resolution spectra without the need for moving parts or low-resolution dispersive optics. This method of broadband spectroscopy is most often accomplished via tight phase locking of two mode-locked lasers or via sophisticated signal processing algorithms, and therefore, long integration times of phase coherent signals are difficult to achieve. Here we demonstrate an alternative approach to dual-comb spectroscopy using two phase modulator combs originating from a single continuous-wave laser capable of > 2 hours of coherent real-time averaging. The dual combs were generated by driving the phase modulators with step-recovery diodes where each comb consisted of > 250 teeth with 203 MHz spacing and spanned > 50 GHz region in the near-infrared. The step-recovery diodes are passive devices that provide low-phase-noise harmonics for efficient coupling into an enhancement cavity at picowatt optical powers. With this approach, we demonstrate the sensitivity to simultaneously monitor ambient levels of CO2, CO, HDO, and H2O in a single spectral region at a maximum acquisition rate of 150 kHz. Robust, compact, low-cost and widely tunable dual-comb systems could enable a network of distributed multiplexed optical sensors.

Effect of Elevated CO2 on the Growth and Macronutrient (N, P and K) Uptake of Annual Wormwood (Artemisia annua L.)

Annual wormwood (Artemisia annua L.) is the only viable source of artemisinin, an antimalarial drug. There is a pressing need to optimize production per cultivated area of this important medicinal plant; however, the effect of increasing atmospheric carbon dioxide (CO2) concentration on its growth is still unclear. Therefore, a pot experiment was conducted in a free-air CO2 enrichment (FACE) facility in Yangzhou City, China. Two A. annua varieties, one wild and one cultivated, were grown under ambient (374 μmol mol−1) and elevated (577 μmol mol−1) CO2 levels to determine the dry matter accumulation and macronutrient uptake of aerial parts. The results showed that stem and leaf yields of both A. annua varieties increased significantly under elevated CO2 due to the enhanced photosynthesis rate. Although nitrogen (N), phosphorus (P), and potassium (K) concentrations in leaves and stems of both varieties decreased under elevated CO2, total shoot N, P, and K uptake of the two varieties were enhanced and the ratios among the concentrations of these nutrients (N:P, N:K, and P:K) were not affected by elevated CO2. Overall, our results provided the evidence that elevated CO2 increased biomass and shoot macronutrient uptake of two A. annua varieties.

Reductions in native grass biomass associated with drought facilitates the invasion of an exotic grass into a model grassland system.

The invasion success of exotic plant species is often dependent on resource availability. Aspects of climate change such as rising atmospheric CO2 concentration and extreme climatic events will directly and indirectly alter resource availability in ecological communities. Understanding how these climate change-associated changes in resource availability will interact with one another to influence the invasion success of exotic plant species is complex. The aim of the study was to assess the establishment success of an invasive exotic species in response to climate change-associated changes in resource availability (CO2 levels and soil water availability) as a result of extreme drought. We grew grassland mesocosms consisting of four co-occurring native grass species common to the Cumberland Plain Woodland of western Sydney, Australia, under ambient and elevated CO2 levels and subjected them to an extreme drought treatment. We then added seeds of a highly invasive C3 grass, Ehrharta erecta, and assessed its establishment success (biomass production and reproductive output). We found that reduced biomass production of the native grasses in response to the extreme drought treatment enhanced the establishment success of E. erecta by creating resource pulses in light and space. Surprisingly, CO2 level did not affect the establishment success of E. erecta. Our results suggest that the invasion risk of grasslands in the future may be coupled to soil water availability and the subsequent response of resident native vegetation therefore making it strongly context- dependent.

大豆主要株型和产量指标对大气CO2和温度升高的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 大豆主要株型和产量指标对大气CO2和温度升高的响应 DOI: 10.5846/stxb201411122240 作者: 作者单位: 南京农业大学,南京农业大学,南京农业大学,南京农业大学,南京农业大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目(31272051,31101491,31470454) Morphological traits and yield of soybean under elevated atmospheric CO2 concentration and temperature Author: Affiliation: Nanjing Agricultural University,Nanjing Agricultural University,Nanjing Agricultural University,Nanjing Agricultural University,Nanjing Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:针对当前气候变暖和大气CO2浓度升高同步发生现实,以高光效大豆品种黑农41(HN41)和3个常规对照品种周豆16号(ZD16)、中豆35号(ZD35)和桂黄豆2号(GHD2)为研究对象,通过开顶式气室模拟高CO2浓度(650μL/L)和温度升高(±0.5-0.6℃)研究了大气CO2和温度升高对大豆的生长发育与产量影响。结果表明,CO2浓度升高对株高、茎粗、单株干重和单株籽粒重影响极显著;温度、CO2与品种互作极显著地影响单株籽粒重。CO2浓度升高有增加大豆株高、茎粗、干重和单株籽粒重的趋势,且高温下CO2浓度升高对株高和茎粗的促进作用更大,而正常温度水平下高CO2浓度升高更有利于干物质积累。与对照CO2浓度比,高CO2浓度显著促进了高温下HN41、ZD16和GHD2的株高,并显著提高了正常温度下HN41、ZD16、ZD35和GHD2的单株干重。与正常温度相比,高温仅显著提高了高CO2处理下HN41的茎粗,并显著提高了对照CO2处理下HN41的单株籽粒重。此外,同一CO2浓度和温度处理下,高光效大豆HN41的茎粗、根冠比和单株籽粒重等都显著高于ZD16、ZD35和GHD2;而仅在正常温度与高CO2浓度处理下HN41的单株干重显著高于ZD16和GHD2。CO2浓度和温度升高显著影响了高光效大豆的生长,其中,高温下CO2浓度升高有利于其生长势,正常温度下CO2浓度升高有利于其光合产物积累。 Abstract:Increasing levels of atmospheric CO2 and temperature are the two most important factors of global climate change. As two key environmental factors for plant growth, the changes in atmospheric CO2 concentration and temperature can affect photosynthetic productivity of crop plants. Moreover, used as a raw material in plant photosynthesis, increasing atmospheric CO2 concentration will have a direct positive impact on photosynthesis and a series of physiological and biochemical process in plants and finally on crop yield. The atmospheric CO2 level is increasing sharply with the expanding scope of human economic activities, which raises Earth surface temperature, eventually leading to global warming. In general, the photosynthetic rate is not saturated in most crop species under ambient CO2 level (about 375 μL/L); hence, the increasing atmospheric CO2 level can enhance the photosynthetic rate in most crop plants. Howerver, the effect of climate change on photosynthesis, and physiological and biochemical processes is much more complex and unknown in most crops, especially in cultivars with high photosynthetic efficiency under the assumption of concomitant global warming and atmospheric CO2 concentration increase. In this study, soybean cultivar HN41 with high photosynthetic efficiency ( ≥ 17.64 μmol [CO2] m-2s-1) and three varieties ZD16, ZD35, and GHD2 with normal photosynthetic efficiency (10.75-15.48 μmol [CO2] m-2s-1) were selected to study morphological traits and yield of soybean under elevated levels of CO2 (650 μL/L vs. ambient CO2) and temperature (± 0.5-0.6℃ vs. ambient temperature). The results indicated that CO2 levels significantly affected plant height and stem diameter, as well as dry weight and seed weight per plant. Temperature levels and the interaction between CO2 concentration and soybean cultivars significantly affected seed weight per plant. Relative to ambient CO2 concentration, elevated levels of CO2 promoted plant height, stem diameter, and dry weight and seed weight per plant, particularly under higher temperature. Moreover, elevated CO2 significantly increased plant height in HN41, ZD16, and GHD2 at high temperature (18.9%, 24.4%, and 31.5%, respectively) and significantly enhanced dry weight per plant in HN41, ZD16, ZD35, and GHD2 at ambient temperature (7.3%, 4.7%, 16.0%, and 18.8%, respectively), in contrast to ambient CO2 levels. Compared with ambient temperature, higher temperature significantly increased only the stem diameter of HN41 under elevated CO2 levels and significantly enhanced the grain weight per plant in HN41 under ambient CO2 levels. In addition, stem diameter, root/shoot ratio, and grain weight per plant in HN41 were significantly greater than those in normal cultivars (ZD16, ZD35, and GHD2) under the same conditions of atmospheric CO2 levels and temperature, whereas dry biomass per plant in HN41 was significantly increased compared with that in ZD16 and GHD2. In conclusion, increase of both atmospheric CO2 levels and temperature significantly affected plant growth of the highly photosynthesis-efficient soybean. Elevated CO2 concentration can promote plant growth particularly at high temperature, whereas elevated CO2 favors accumulation of photosynthetic products at ambient temperature especially for the highly photosynthesis-efficient soybean. 参考文献 相似文献 引证文献

Elevated Carbon Dioxide Level Suppresses Nutritional Quality of Lettuce and Spinach

Rising global CO2 levels are a major factor that impacts not only the environment but also many plant functions including growth, productivity and nutritional quality. The study examined the impact of elevated [CO2] on nutritional quality and growth characteristics of lettuce (Lactuca sativa) and spinach (Spinacia oleracea). Elevated [CO2] decreased the concentration of many important nutrients including nitrogen (protein), potassium and phosphorus in the edible parts of both lettuce and spinach. The nitrogen concentration in lettuce shoots was reduced by more than 30% at elevated [CO2] compared to the plants grown at ambient level of CO2. Similarly the concentration of a number of micronutrients including sulfur, zinc, copper and magnesium, was depressed in lettuce shoots. Although the total phenolic content and antioxidant capacity were higher in lettuce at elevated CO2, they were not affected in spinach. The photosynthetic activity was variable among the plant species while there was no increase in the carbon accumulation in these plants at elevated [CO2]. However, there was significant reduction in the leaf stomatal conductance in both lettuce and spinach in response to higher [CO2], which is likely affect both water loss from the leaves and their photosynthetic activity. The results indicate a broad adverse impact of rising [CO2] on the nutritional quality of commonly consumed leafy vegetables namely, lettuce and spinach.

Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations

Ocean acidification (OA), induced by rapid anthropogenic CO2 rise and its dissolution in seawater, is known to have consequences for marine organisms. However, knowledge on the evolutionary responses of phytoplankton to OA has been poorly studied. Here we examined the coccolithophore Gephyrocapsa oceanica, while growing it for 2000 generations under ambient and elevated CO2 levels. While OA stimulated growth in the earlier selection period (from generations ~700 to ~1550), it reduced it in the later selection period up to 2000 generations. Similarly, stimulated production of particulate organic carbon and nitrogen reduced with increasing selection period and decreased under OA up to 2000 generations. The specific adaptation of growth to OA disappeared in generations 1700 to 2000 when compared with that at 1000 generations. Both phenotypic plasticity and fitness decreased within selection time, suggesting that the species' resilience to OA decreased after 2000 generations under high CO2 selection.

Warming and Elevated CO2 Interact to Drive Rapid Shifts in Marine Community Production.

Predicting the outcome of future climate change requires an understanding of how alterations in multiple environmental factors manifest in natural communities and affect ecosystem functioning. We conducted an in situ, fully factorial field manipulation of CO2 and temperature on a rocky shoreline in southeastern Alaska, USA. Warming strongly impacted functioning of tide pool systems within one month, with the rate of net community production (NCP) more than doubling in warmed pools under ambient CO2 levels relative to initial NCP values. However, in pools with added CO2, NCP was unaffected by warming. Productivity responses paralleled changes in the carbon-to-nitrogen ratio of a red alga, the most abundant primary producer species in the system, highlighting the direct link between physiology and ecosystem functioning. These observed changes in algal physiology and community productivity in response to our manipulations indicate the potential for natural systems to shift rapidly in response to changing climatic conditions and for multiple environmental factors to act antagonistically.

Combined effect of elevated CO2 level and temperature on germination and initial growth of Montrichardia arborescens (L.) Schott (Araceae): a microcosm experiment

IPCC predictions indicate an increase in temperatures by 1.5–7°C in some Amazonian regions during the twenty-first century. These changes could disrupt the present distribution patterns of organisms, including wetland plant species. In this work, we determined in microcosms the effects of scenarios combining elevated temperature and atmospheric CO2 concentration on the germination and initial growth of the arborescent Amazonian aquatic macrophyte Montrichardia arborescens. Seeds were germinated, and seedlings produced were monitored over a 5-month period in four microcosms: Control: ambient temperature and CO2 level; Mild: Control + 1.5°C and + 200 ppm CO2; intermediate: control + 2.5°C and + 400 ppm CO2; Extreme: Control + 4.5°C and + 850 ppm of CO2. Rapid light response curves and Fv/Fm values taken in seedlings showed a decrease in electron transportation rate with CO2 and temperature elevation. Mild and Intermediate treatments stimulated biomass production; Extreme treatment and Control produced similar results. The severe climatic changes expected in the future may negatively influence carbon accumulation in M. arborescens. Since aquatic macrophytes in Amazonian wetlands and wetlands worldwide are key plant species, further studies are needed to predict their fate in a global change perspective.

Ocean acidification increases the accumulation of toxic phenolic compounds across trophic levels.

Increasing atmospheric CO2 concentrations are causing ocean acidification (OA), altering carbonate chemistry with consequences for marine organisms. Here we show that OA increases by 46–212% the production of phenolic compounds in phytoplankton grown under the elevated CO2 concentrations projected for the end of this century, compared with the ambient CO2 level. At the same time, mitochondrial respiration rate is enhanced under elevated CO2 concentrations by 130–160% in a single species or mixed phytoplankton assemblage. When fed with phytoplankton cells grown under OA, zooplankton assemblages have significantly higher phenolic compound content, by about 28–48%. The functional consequences of the increased accumulation of toxic phenolic compounds in primary and secondary producers have the potential to have profound consequences for marine ecosystem and seafood quality, with the possibility that fishery industries could be influenced as a result of progressive ocean changes.