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Radioecology
Abstract
Radionuclides have now become part and parcel of our lives, and there does not seem any escape from them. Radionuclides have shown immense application potential in various fields of science and medicine, and thus, their management acquires utmost priority. Radioisotopes also command natural existence in almost all the excavated mineral ores and fossil fuels besides fertilizer and industrial waste that is generated following burning of fossil fuels. Widespread acceptability of nuclear power plants as the most potent, viable, and practical alternative to produce power to meet huge electricity demand of the domestic and industrial sectors further reveals how the nuclear technology has entered our lives. Add to it the demolishing power of the nuclear technology which is also muscled several times in the past by the developing and developed countries alike. Enrichment of water bodies with radioactive uranium of geological origin is also a concern. Add to it the challenge of climate change that we greatly impede or hasten the geological transition of radionuclides from the nonmobile or immobilized moieties into the mobile forms to contaminate soil and water bodies across a larger region, thus also risking the contamination of food chain. This chapter collates information available on changes in soil and plant attributes that may take place under the climate change scenario to alter the transfer of radioactivity in the environment particularly the soil to plant continuum. The triggers, challenges, and likely adaptation opportunities are discussed.
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Abstract.
To investigate the effect of drought stress on water relations, stomatal density, chlorophyll content, and yield of rapeseed, an experiment was done with four levels of drought stress including L1 (Field Capacity, FC), L2 (70% Available Water Content, AWC), L3 (50% AWC), and L4 (30% AWC), within three growth stages including stem elongation (T1), the onset of flowering (T2) and silique formation period (T3) at the University of Maragheh in 2013. The results showed that the lowest relative water content and leaf water potential were obtained at 30% AWC and silique development stage. Meanwhile, the highest water use efficiency (WUE) was observed during flower bud and silique development stages and 70% AWC. Furthermore, the results demonstrated that stomatal was only influenced by the levels of applied stresses and the highest stomatal density was recorded in 30% AWC. Implementation of 30% AWC in silique development stage diminished chlorophylls a, b, and total chlorophyll content to their lowest points so that compared to field capacity (L1), they decreased about 59, 67, and 62 percent, respectively. Likewise, the least grain yield belonged to stress application at the flower bud development stage and 30% AWC stress level. Also, the grain yield loss in L4×T3 (30%AWC in silique formation period) treatment in comparison with the L1 (Field Capacity, FC) was 46.2 percent. Seed protein content was adversely affected by stress level and any decrease in AWC led to a concomitant decrease in protein content. At the same time, the seed oil content was influenced by stress application times. Water deficit stress during flower bud formation had the greatest adverse effect on seeds oil content. Overall, it was concluded that severe water deficit (30% AWC) led to the decrease of chlorophylls a, b, total chlorophyll, seed protein, oil content, and yield.
Botanical pesticides can be recommended as an ecochemical and sustainable strategy in the management of agricultural pests. Because of their biodegradable nature, systemicity after application, capacity to alter the behavior of target pests and favorable safety profile, it is hoped that plant-based pesticides play a significant role in achieving evergreen revolution. Azadirachta indica is widely grown all over the tropic and is the most useful traditional medicinal plant in India. Each and every part of it has diverse applications due to presence of many biologically active ingredients such as Nimbidin, Nimbin, Nimbolide, Gedunin, azadirachtin, mahmoodin, gallic acid etc. Different neem products containing different neem compounds are having various applications including antialergic, anti-inflammatory, insecticidal, nematicidal, spermatocidal, antidermatic, antiviral, antifungal, anti AIDS, anticancer, antimalerial, antipyretic and many other biological activities. Therefore, this review gives clear idea about agricultural applications of botanicals.
Climate change is expected to alter precipitation patterns worldwide, which can have direct effects on streamflow dynamics. In many tropical regions, climate-driven changes in rainfall are predicted to decrease streamflow and increase flash flooding, but the implications of these changes for stream ecosystem function are poorly understood. We used a rainfall gradient on Hawaii Island that mimics projected changes in rainfall and streamflow in order to estimate how climate change affects nutrient recycling. We measured per-capita excre-tion (nitrogen, phosphorus) and egestion rates of three dominant taxa (shrimp, caddisfly, midge) in eight streams along the gradient for 3 years. We scaled these rates to the population and community levels and measured nitrogen and phosphorus demand of the ecosystem to estimate if the relative contribution of nutrients supplied by invertebrates changes along the gradient. Across all three taxa, population egestion and excretion rates declined by 10-fold in drier streams. These declines were driven by lower population density, rather than differences in per-capita rates. Under the current climate scenario, community excretion supplied up to 70% of the nitrogen demand, which was 10-fold lower with projected changes in rainfall. Conversely, community excretion supplied up to 5% of the phosphorus demand, which did not vary across the rainfall gradient. This difference indicates that climate change may exacerbate nitrogen limitations in tropical island streams, and change the balance of nitrogen and phosphorus dynamics. Our study also demonstrates that space-for-time substitutions are a valuable tool to examine implications of climate change on ecosystem function in freshwater systems.
Carbon dioxide (CO 2) is mainly universal greenhouse gas associated with climate change. However, beyond CO 2 , some other greenhouse gases (GHGs) like methane (CH 4) and nitrous oxide (N 2 O), being two notable gases, contribute to global warming. Since 1900, the concentrations of CO 2 and non-CO 2 GHG emissions have been elevating, and due to the effects of the previous industrial revolution which is responsible for climate forcing. Globally, emissions of CO 2 , CH 4 , and N 2 O from agricultural sectors are increasing as around 1% annually. Moreover, deforestation also contributes 12-17% of total global GHGs. Perhaps, the average temperature is likely to increase globally, at least 2°C by 2100-by mid-century. These circumstances are responsible for climate forcing, which is the source of various human health diseases and environmental risks. From agricultural soils, rhizospheric microbial communities have a significant role in the emissions of greenhouse gases. Every year, microbial communities release approximately 1.5-3 billion tons of carbon into the atmospheric environment. Microbial nitrification, denitri-fication, and respiration are the essential processes that affect the nitrogen cycle in the terrestrial environment. In the twenty-first century, climate change is the major threat faced by human beings. Climate change adversely influences human health to cause numerous diseases due to their direct association with climate change. This review highlights the different anthropogenic GHG emission sources, the response of microbial communities to climate change, climate forcing potential, and mitigation strategies through different agricultural management approaches and microbial communities.
Drylands cover 41% of the earth’s land surface and include 45% of the world’s agricultural land. These regions are among the most vulnerable ecosystems to anthropogenic climate and land use change and are under threat of desertification. Understanding the roles of anthropogenic climate change, which includes the CO2 fertilization effect, and land use in driving desertification is essential for effective policy responses but remains poorly quantified with methodological differences resulting in large variations in attribution. Here, we perform the first observation-based attribution study of desertification that accounts for climate change, climate variability, CO2 fertilization as well as both the gradual and rapid ecosystem changes caused by land use. We found that, between 1982 and 2015, 6% of the world’s drylands underwent desertification driven by unsustainable land use practices compounded by anthropogenic climate change. Despite an average global greening, anthropogenic climate change has degraded 12.6% (5.43 million km2) of drylands, contributing to desertification and affecting 213 million people, 93% of who live in developing economies. Drylands cover nearly half of Earth’s surface, yet how they will fare in light of anthropogenic climate change is debated. Here the authors find that over the past 40 years climate change has pushed ~13% of drylands towards desertification threatening hundreds of millions of people in developing nations.
Geographic location and connected environmental and edaphic factors like temperature, rainfall, soil type, and composition influence the presence and the total content of specific plant compounds as well as the presence of a certain chemotype. This study evaluated whether geographic, edaphic, and climatic information can be utilized to predict the presence of specific compounds from medicinal or aromatic plants. Furthermore, we tested rapid analytical methods based on near infrared spectroscopy (NIR) coupled with gas chromatography/flame ionization (GC/FID) and gas chromatography/mass spectrometry (GC/MS) analytical methods for characterization and classification metabolite profiling of Zataria multiflora Boiss. populations. Z. multiflora is an aromatic, perennial plant with interesting pharmacological and biological properties. It is widely dispersed in Iran as well as in Pakistan and Afghanistan. Here, we studied the effect of
environmental factors on essential oil (EO) content and the composition and distribution of chemotypes. Our results indicate that this species grows predominantly in areas rich in calcium, iron, potassium, and aluminum, with mean rainfall of 40.46 to 302.72 mm·year−1 and mean annual temperature of 14.90°C to 28.80°C. EO content ranged from 2.75% to 5.89%. Carvacrol (10.56–73.31%), thymol (3.51–48.12%), linalool (0.90–55.38%), and p-cymene (1.66–13.96%) were the major constituents, which classified 14 populations into three chemotypes. Corresponding to the phytochemical cluster analysis, the hierarchical cluster analysis (HCA) based on NIR data also recognized the carvacrol, thymol, and linalool chemotypes. Hence, NIR has the potential to be applied as a useful tool to determine rapidly the chemotypes of Z. multiflora and similar herbs. EO and EO constituent content correlated with different geographic location, climate, and edaphic factors. The structural equation models (SEMs) approach revealed direct effects of soil factors (texture, phosphor, pH) and mostly indirect effects of latitude and altitude directly affecting, e.g., soil factors. Our approach of identifying environmental predictors for EO content, chemotype or presence of high amounts of specific compounds can help to select regions for sampling plant material with the desired chemical profile for direct use or for breeding.
The ocean provides resources key to human health and well-being, including food, oxygen, livelihoods, blue spaces, and medicines. The global threat to these resources posed by accelerating ocean acidification is becoming increasingly evident as the world’s oceans absorb carbon dioxide emissions. While ocean acidification was initially perceived as a threat only to the marine realm, here we argue that it is also an emerging human health issue. Specifically, we explore how ocean acidification affects the quantity and quality of resources key to human health and well-being in the context of: (1) malnutrition and poisoning, (2) respiratory issues, (3) mental health impacts, and (4) development of medical resources. We explore mitigation and adaptation management strategies that can be implemented to strengthen the capacity of acidifying oceans to continue providing human health benefits. Importantly, we emphasize that the cost of such actions will be dependent upon the socioeconomic context; specifically, costs will likely be greater for socioeconomically disadvantaged populations, exacerbating the current inequitable distribution of environmental and human health challenges. Given the scale of ocean acidification impacts on human health and well-being, recognizing and researching these complexities may allow the adaptation of management such that not only are the harms to human health reduced but the benefits enhanced.
In December 2019, the outbreak of viral disease labeled as Novel Coronavirus started in Wuhan, China, which later came to be known as Covid-19. The disease has spread in almost every part of the world and has been declared a global pandemic in March 2020 by World Health Organization (WHO). The corona virus outbreak has emerged as one of the deadliest pandemics of all time in human history. The ongoing pandemic of COVID-19 has forced several countries of the world to observe complete lockdown forcing people to live in their homes. India also faced the phase of total lockdown for 21 days (in first phase) to avoid the spread of coronavirus to the maximum possible extent. This lockdown impacted the pollution levels of environment and improved air and water quality in the short span owing to very less human activities. The present work scientifically analyzed the available data for primary air pollutants (PM2.5, NO2, SO2 and CO) from two major Indian cities, Lucknow and New Delhi. The analysis was based on air quality data for before lockdown and after lockdown (first phase of 21 days) periods of 21 days each. The results showed significant decline in the studied air pollution indices and demonstrated improvement of air quality in both the cities. The major impact was seen in the levels of PM2.5, NO2 and CO. The levels of SO2 showed less significant decline during the lockdown period. The results are presented with future perspectives to mitigate air pollution in near future by adopting the short and periodical lockdown as a tool.
Drought seriously curtails growth, physiology and productivity in rapeseed (Brassica napus). Although drought tolerance is a complex trait, efficient phenotyping and genotyping has led to the identification of novel marker-trait associations underlying drought tolerance. A diverse panel of 228 Brassica accessions was phenotyped under normal (without stress) and water-stress conditions, simulated by polyethylene glycol (PEG-6000) (15% PEG stress) at the seedling stage; stress tolerance index (STI) and stress susceptibility index (SSI) values were acquired. Genome-wide association studies (GWAS) using 201 817 high quality SNPs identified 314 marker-trait associations strongly linked with drought indices and distributed across all nineteen chromosomes in both the A and C genomes. None of these quantitative trait loci (QTL) had been previously identified by other studies. We identified 85 genes underlying these QTL (most within 100 kb of associated SNPs) which were orthologous to Arabidopsis genes known to be associated with drought tolerance. Our study provides a novel resource for breeding drought-tolerant Brassica crops.
As the largest developing country in the world, China has witnessed fast-paced urbanization over the past three decades with rapid economic growth. In fact, urbanization has been not only shown to promote economic growth and improve the livelihood of people but also can increase demands of regional logistics. Therefore, a better understanding of the relationship between urbanization and regional logistics is important for China’s future sustainable development. The development of urban residential area and heterogeneous, modern society as well regional logistics are running two abreast. The regional logistics can promote the development of new-type urbanization jointly by promoting industrial concentration and logistics demand, enhancing the residents’ quality of life and improving the infrastructure and logistics technology. In this paper, the index system and evaluation model for evaluating the development of regional logistics and the new-type urbanization are constructed. Further, the econometric analysis is utilized such as correlation analysis, co-integration test, and error correction model to explore relationships of the new-type urbanization development and regional logistics development in Liaoning Province. The results showed that there was a long-term stable equilibrium relationship between the new-type urbanization and regional logistics. The findings have important implications for Chinese policymakers that on the path towards a sustainable urbanization and regional reverse, this must be taken into consideration. The paper concludes providing some strategies that might be helpful to the policymakers in formulating development policies for sustainable urbanization.
Worldwide, ecosystems are threatened by global changes, including biological invasions. Invasive species arriving in novel environments experience new climatic conditions that can affect their successful establishment. Determining the response of functional traits and fitness components of invasive populations from contrasting environments can provide a useful framework to assess species responses to climate change and the variability of these responses among source populations. Much research on macrophytes has focused on establishment from clonal fragments; however, colonization from sexual propagules has rarely been studied. Our objective was to compare trait responses of plants generated from sexual propagules sourced from three climatic regions but grown under common environmental conditions, using L. peploides subsp. montevidensis as a model taxon.
We grew seedlings to reproductive stage in experimental mesocosms under a mediterranean California (MCA) climate from seeds collected in oceanic France (OFR), mediterranean France (MFR), and MCA.
Seed source region was a major factor influencing differences among invasive plants recruiting from sexual propagules of L. peploides subsp. montevidensis. Trait responses of young individual recruits from MCA and OFR, sourced from geographically distant and climatically distinct source regions, were the most different. The MCA individuals accumulated more biomass, flowered earlier, and had higher leaf N concentrations than the OFR plants. Those from MFR had intermediate profiles.
By showing that the closer a seedling is from its parental climate, the better it performs, this study provides new insights to the understanding of colonization of invasive plant species and informs its management under novel and changing environmental conditions. Full text available at: https://bsapubs.onlinelibrary.wiley.com/doi/full/10.1002/ajb2.1475
Soil radio-cesium (Cs) contamination caused by nuclear accidents is a major public concern. In this review, we presented the behavior of radio-Cs in soils, the relationship between Cs+ and potassium (K) ion uptake from soils, and the Cs+ uptake model proposed previously. Finally, we introduced the newly elucidated mechanism of Cs+ uptake in rice plants and compared it with the previously proposed Cs+ uptake model. Cs is a trace element in soil. It is toxic to plants when absorbed at high concentrations, although this rarely occurs under normal environmental conditions. Nevertheless, radio-Cs released during nuclear weapon tests or nuclear power plant accidents is absorbed by plants, thus entering the food chain. As Cs+ strongly binds to the frayed edge sites of illitic clays in soil, it is hardly moved by the infiltration of rainwater. However, plants have a strong ability for inorganic ions uptake, causing re-diffusion of radio-Cs+ into ecosystems and radioactive contamination of food. It is hypothesized that Cs+ is absorbed by plants through the same mechanism implemented in K+ uptake. However, the dynamics of the two elements do not always coincide in their transition from soil to plants and inside the plants. A previously proposed model of Cs uptake by higher plants stated that Cs+ is absorbed through high affinity potassium (HAK) family of transporters and voltage-insensitive cation (VIC) channels. A knockout line of a HAK transporter gene (oshak1) in rice revealed that the HAK transporter OsHAK1 is the main route of Cs+ influx into rice plants, especially in low-potassium conditions. The K+ uptake rates did not differ greatly between the oshak1 and wildtype. On the surface of rice roots, potassium-transport systems other than OsHAK1 make little or no contribution to Cs+ uptake. It is almost certain that OsAKT1 does not mediate the Cs uptake. Under normal soil conditions, 80–90% of Cs uptake into the roots is mediated by OsHAK1 and the rest by VIC channels. Except for the difference between the contribution ratio of HAK and VIC channels in Cs uptake, these results are consistent with the conventional model.
Development of abiotic stress tolerant rice cultivars is necessary for sustainable rice production under the scenario of global climate change, dwindling fresh water resources and increase in salt affected areas. Several genes from rice have been functionally validated by using EMS mutants and transgenics. Often, many of these desirable alleles are not available indica rice which is mainly cultivated, and where available, introgression of these alleles into elite cultivars is a time and labour intensive process, in addition to the potential introgression of non-desirable genes due to linkage. CRISPR-Cas technology helps development of elite cultivars with desirable alleles by precision gene editing. Hence, this study was carried out to create mutant alleles of drought and salt tolerance (DST) gene by using CRISPR-Cas9 gene editing in indica rice cv. MTU1010. We used two different gRNAs to target regions of DST protein that might be involved in protein–protein interaction and successfully generated different mutant alleles of DST gene. We selected homozygous dst mutant with 366 bp deletion between the two gRNAs for phenotypic analysis. This 366 bp deletion led to the deletion of amino acid residues from 184 to 305 in frame, and hence the mutant was named as dst∆184–305. The dst∆184–305 mutation induced by CRISPR-Cas9 method in DST gene in indica rice cv. MTU1010 phenocopied EMS-induced dst (N69D) mutation reported earlier in japonica cultivar. The dst∆184–305 mutant produced leaves with broader width and reduced stomatal density, and thus enhanced leaf water retention under dehydration stress. Our study showed that the reduction in stomatal density in loss of function mutants of dst is, at least, in part due to downregulation of stomatal developmental genes SPCH1, MUTE and ICE1. The Cas9-free dst∆184–305 mutant exhibited moderate level tolerance to osmotic stress and high level of salt stress in seedling stage. Thus, dst mutant alleles generated in this study will be useful for improving drought and salt tolerance and grain yield in indica rice cultivars.
Crop production is facing the increase of salinity in soils and irrigation waters. This is a widespread problem that affects crops with high economic importance and reduces yields. Salinity causes oxidative stress in plants which induce complex defensive mechanisms involving the antioxidant system and osmoprotector compounds. Ca²⁺ plays a pivotal role in counteracting salt stress, and the modification of the Ca²⁺ vacuolar transporter CAX1 could represent a potential method to improve tolerance to salinity. Three new CAX1 variants in Brassica rapa (BraA.cax1a) were generated using TILLING strategy. The objective of this work is to evaluate the tolerance of these mutants to saline conditions. For this, BraA.cax1a mutants and the parental line R-o-18 were grown in pots under control and saline conditions (150 mM NaCl). Parameters of biomass, ions accumulation, antioxidant compounds concentration and antioxidant enzyme activities, heat shock protein 70 (HSP70) occurrence, and proline (Pro) levels were measured. According to the results, BraA.cax1a-4 mutation provided a higher tolerance to salinity stress. Thus, BraA.cax1a-4 plants showed higher biomass; higher Ca²⁺ and K⁺ accumulation in the shoot, a lower Na⁺/K⁺ ratio, an enhanced ROS scavenging (increased superoxide dismutase and catalase activities) and an enhanced ascorbate redox state. BraA.cax1a-4 and BraA.cax1a-12 showed higher K⁺ transport to the shoot which could contribute to their lower lipid peroxidation. In contrast, BraA.cax1a-7 showed a lower antioxidant response. Besides, an increased occurrence of cytosolic and chloroplastic HSP70 isoforms and Pro levels could contribute to protect these B. rapa mutants from saline stress. Therefore, this study identifies a potential useful genotype that could be used to enhance salt tolerance of crops.
Drylands cover 41% of Earth’s surface and are the largest source of interannual variability in the global carbon sink. Drylands are projected to experience accelerated expansion over the next century, but the implications of this expansion on variability in gross primary production (GPP) remain elusive. Here we show that by 2100 total dryland GPP will increase by 12 ± 3% relative to the 2000–2014 baseline. Because drylands will largely expand into formerly productive ecosystems, this increase in dryland GPP may not increase global GPP. Further, GPP per unit dryland area will decrease as degradation of historical drylands outpaces the higher GPP of expanded drylands. Dryland expansion and climate-induced conversions among sub-humid, semi-arid, arid, and hyper-arid subtypes will lead to substantial changes in regional and subtype contributions to global dryland GPP variability. Our results highlight the vulnerability of dryland subtypes to more frequent and severe climate extremes and suggest that regional variations will require different mitigation strategies.
The mutualism between plants and their pollinators provides globally important ecosystem services, but it is likely to be disrupted by global warming that can cause mismatches between both halves of this interaction. In this review, we summarise the available evidence on (i) spatial or (ii) phenological shifts of one or both of the actors of this mutualism. While the occurrence of future spatial mismatches is predominantly theoretical and based on predictive models, there is growing empirical evidence of phenological mismatches occurring at the present day. Mismatches may also occur when pollinators and their host plants are still found together. These mismatches can arise due to (iii) morphological modifications and (iv) disruptions to host attraction and foraging behaviours, and it is expected that these mismatches will lead to novel community assemblages. Overall plant–pollinator interactions seem to be resilient biological networks, particularly because generalist species can buffer these changes due to their plastic behaviour. However, we currently lack information on where and why spatial mismatches do occur and how they impact the fitness of plants and pollinators, in order to fully assess if adaptive evolutionary changes can keep pace with global warming predictions.
Cyclone Fani hit the Koonthankulam Bird Sanctuary, Tirunelveli District, Tamil Nadu, India on
29th April, 2019 and inflicted morbidity and mortality in painted storks (Mycteria leucocephala).
The juvenile painted storks perching on the trees fell along with nests and 13 were referred to
Veterinary Clinical Complex, Veterinary College and Research Institute, Tirunelveli, South India
in critical stages. On clinical examination two birds were in shock, one had fracture of pelvis and
left femur which was treated by soft bandaging. The remaining 10 birds requiring procedures
were inducted and maintained anaesthesia following pre-oxygenation for 5 minutes, Isoflurane
was administered as inhalant anaesthetic in 100 per cent oxygen (3 L/min) at a concentration of
4 to 5 per cent for induction and 2 per cent for maintenance through a customized face mask
made of plastic intravenous fluid bottle. For the long bone fractures, intramedullary pinning was
performed in 5 cases of tibio-trasal and tarso-metatarsal fractures and Plaster of Paris bandage
was applied in 4 cases of tibio-trasal and tarso-metatarsal fractures including radius-ulna
fracture in one case. Anaesthesia was well tolerated with a mean Standard reflex score of 1.55
±1.23 after induction. Intramedullary pinning and Plaster of Paris bandage were tolerated and
aided in healing of long bone fractures. The birds in shock (2), pelvis fracture (1) and radiusulna
fractures (1) died during the post treatment period in the Rehabilitation centre and the 9
recovered birds were released. The study indicated that isoflurane was a safe and ideal inhalant
anaesthetic in Painted Storks and intramedullary pinning and Plaster of Paris bandage were
well tolerated and they aided in the healing of long bone fractures of pelvic limbs in painted
storks.
Son Beel wetland is facing ecosystem marginalization where ecosystem services aren’t being priced & reflected in decision making which proves complete market failure. Agricultural produce from converted lake does not reflect values lost due to flood protection, fisheries, biodiversity etc. People who deteriorate are not the same whose livelihoods are affected leading to continued degradation of the wetland. Wetlands governance has so far been failing to address sectoral policies providing incentives leads to wetlands depletion. Son Beel is the home to diversity of fishes in particular to an important habitat for small & tinny fishes. There are about 500 families engaged in the net building & designing and these fisher folk communities are linked this wetland to local market networks. It has been estimated by state government report and records that there are more than 35,000 families directly dependent on the Beel for traditional fishing system. Evergreen Forest comprises 40% peripheral area of the Beel. Son Beel is an important habitat for some reptiles and other various aquatic species. This wetland is home for migrant Siberian birds for 3 months every year. Son Beel is abundantly rich in fish biodiversity and around 69 different fish species are found among which small fishes are the most (D.Kar et. al, 2006). The economic value is the monetary value of goods & services offered by wetlands in which people’s preferences are expressed through choices & trade-offs. Total Economic Value (TEV) is the sum of the values of all wetland ecosystem services flows from providers to beneficiaries over the given spatial & temporal scales. Economic valuation is a powerful tool since it provides means to measure & quantify trade-offs between multiple wetland uses (Barbier et al., 1997) via monetary matrices. Valuation of wetland ecosystem in India has some major gaps likewise; the confusion of terminologies between intermediate & final ecosystem services, has led to double-counting that can inflate values that can seriously impact the credibility of economic valuation. (Johnston & Russel, 2011). The gap of methodological challenges in linking ecosystem characteristics to final ecosystem services is a serious constraint to current valuation process. Lack of clear guidance on relating ecological compensation programmes to conservation targets is a major loophole in ecosystem valuation in India. We tried the best to mitigate these gaps in the ecosystem valuation of Son Beel Wetland. Major aim & objective of our valuation is to provide useful information inputs to the wetland governance to sustain wetland for multiple benefits. Development of ecological production functions & non market valuation methods need ecological & social data which is currently unavailable in India. We shall produce this paper before the State Government of Assam to take adequate measures in protection & conservation of wetlands. We estimated monetary value of Son Beel is from a minimum of $88/Hectare/year to maximum of $29,716/Hectare/Year. Son Beel provides a wide range of natural capital flow in terms ecosystem services for the life & livelihood of people & community. We need to ensure that wetland conservation, wise use & restoration are an integral part to SDGs planning & implementation. Integrating wetlands services & benefits in Nationally Determined Contributions for the Paris Agreement on Climate Change is critical for achieving SDGs. Placing a value on nature’s ecosystem services shouldn’t be misconstrued as ‘putting a price on nature. The authors will strongly recommend the site should declare as Ramsar site of Wetland or such constructive steps should take by the authorities for its better conservation.
Dengue is one of the most dangerous vector-borne diseases transmitted by Aedes mosquitoes. The use of mosquito repellents to protect human hosts and insecticides to reduce the mosquito population is a crucial strategy to prevent the disease. Here, we reported larvicidal and repellent activities of Mentha arvensis L. essential oil against Aedes aegypti, the main vector of the disease. The essential oil was extracted by hydro-distillation from the aromatic plant grown in Vietnam. The yield was 0.67% based on the weight of fresh leaves. The essential oil was analyzed by gas chromatography-mass spectrometry (GC-MS). The main components were menthol (66.04%), menthyl acetate (22.19%), menthone (2.51%), and limonene (2.04%). Toxicity test on Aedes aegypti larvae showed that the median lethal concentrations, LC50 and LC90 were 78.1 ppm (part per million) and 125.7 ppm, respectively. Besides, the essential oil showed excellent repellency on Aedes aegypti mosquitoes. At 25%, 50%, and 100% concentration, the respective complete protection times (CPTs) were 45 min, 90 min, and 165 min. When adding 5% vanillin to the essential oil (25%), the complete protection time of the essential oil increased up to 120 min. In conclusion, the EO from Mentha arvensis L. has been shown to be a promising natural larvicide and repellent against Aedes aegypti mosquitoes.
Recent observational evidence suggests that nighttime temperatures are increasing faster than daytime temperatures, while in some regions precipitation events are becoming less frequent and more intense. The combined ecological impacts of these climatic changes on crassulacean acid metabolism (CAM) plants and their interactions with other functional groups (i.e., grass communities) remain poorly understood. Here we developed a growth chamber experiment to investigate how two CAM–grass communities in desert ecosystems of the southwestern United States and northern Mexico respond to asymmetric warming and increasing rainfall variability. Grasses generally showed competitive advantages over CAM plants with increasing rainfall variability under ambient temperature conditions. In contrast, asymmetric warming caused mortality of both grass species (Bouteloua eriopoda and Bouteloua curtipendula) in both rainfall treatments due to enhanced drought stress. Grass mortality indirectly favored CAM plants even though the biomass of both CAM species Cylindropuntia imbricata and Opuntia phaeacantha significantly decreased. The stem’s volume-to-surface ratio of C. imbricata was significantly higher in mixture than in monoculture under ambient temperature (both P < 0.0014); however, the difference became insignificant under asymmetric warming (both P > 0.1625), suggesting that warming weakens the negative effects of interspecific competition on CAM plant growth. Our findings suggest that while the increase in intra-annual rainfall variability enhances grass productivity, asymmetric warming may lead to grass mortality, thereby indirectly favoring the expansion of co-existing CAM plants. This study provides novel experimental evidence showing how the ongoing changes in global warming and rainfall variability affect CAM–grass growth and interactions in dryland ecosystems.
One of our era's greatest scourges is air pollution, on account not only of its impact on climate change but also its impact on public and individual health due to increasing morbidity and mortality. There are many pollutants that are major factors in disease in humans. Among them, Particulate Matter (PM), particles of variable but very small diameter, penetrate the respiratory system via inhalation, causing respiratory and cardiovascular diseases, reproductive and central nervous system dysfunctions, and cancer. Despite the fact that ozone in the stratosphere plays a protective role against ultraviolet irradiation, it is harmful when in high concentration at ground level, also affecting the respiratory and cardiovascular system. Furthermore, nitrogen oxide, sulfur dioxide, Volatile Organic Compounds (VOCs), dioxins, and polycyclic aromatic hydrocarbons (PAHs) are all considered air pollutants that are harmful to humans. Carbon monoxide can even provoke direct poisoning when breathed in at high levels. Heavy metals such as lead, when absorbed into the human body, can lead to direct poisoning or chronic intoxication, depending on exposure. Diseases occurring from the aforementioned substances include principally respiratory problems such as Chronic Obstructive Pulmonary Disease (COPD), asthma, bronchiolitis, and also lung cancer, cardiovascular events, central nervous system dysfunctions, and cutaneous diseases. Last but not least, climate change resulting from environmental pollution affects the geographical distribution of many infectious diseases, as do natural disasters. The only way to tackle this problem is through public awareness coupled with a multidisciplinary approach by scientific experts; national and international organizations must address the emergence of this threat and propose sustainable solutions.
This study uses an integrated modeling framework to assess the socio-economic impacts of climate change on Indian agriculture. Crop simulation model is used to estimate the yield changes under various climate change scenarios for two main cereal crops, rice and wheat. Aggregated crop yield changes are then introduced as gradually occurring supply shocks to the economy in an applied general equilibrium model and the socio-economic impacts of climate change are assessed. The results indicate that the projected large changes in the climate would lead to significant reductions in the crop yields, which in turn adversely affect the agricultural production. The economic and welfare impacts, captured through change in indicators such as value added and calorie intake, show that climate change would place significant burden on the economy. The results also show that people in the poorer sections of the population are likely to bear a greater share of the burden imposed by the climate change.
Heat stress is one of the major limitations to crop productivity. In the present study, an efficient method of screening was adopted for identification of heat tolerant Indian Mustard genotypes by applying 4-day cycle of heat stress to seedlings. Thirty-four genotypes were screened based upon lipid peroxidation and survival percentage and classified them into five different classes according to membership function value (MFV) for response against high temperature. The maximum and minimum value of mean MFV were 0.89 (highly heat tolerant, TPM1) and 0.12 (highly heat sensitive, JM2), respectively. The coefficient of determination (R2) between the mean MFV and the heat tolerance index (HTI) of MDA content, survival percentage was 0.914 and 0.808 suggesting that these parameters are reliable traits to evaluate the heat tolerance of Brassica juncea genotypes. The evaluation method was further validated using identified contrasting genotypes and assessment of heat stress associated biochemical parameters. Results showed efficient recovery of tolerant genotype as compared to sensitive genotype. Expression profiling of heat stress-related genes (HSP21 and HSFA7A) showed significant upregulation in the tolerant genotype (TPM1) (9.73- and 4.87-fold, respectively) as compared to the sensitive genotype (JM2) (4.18- and 1.73-fold, respectively) under heat stress condition. The results imply development of an efficient screening method which is useful for evaluation and breeding of thermo-tolerant B. juncea.
Freshwater ecosystems provide irreplaceable services for both nature and society. The quality and quantity of freshwater affect biogeochemical processes and ecological dynamics that determine biodiversity, ecosystem productivity, and human health and welfare at local, regional and global scales. Freshwater ecosystems and their associated riparian habitats are amongst the most biologically diverse on Earth, and have inestimable economic, health, cultural, scientific and educational values. Yet human impacts to lakes, rivers, streams, wetlands and groundwater are dramatically reducing biodiversity and robbing critical natural resources and services from current and future generations. Freshwater biodiversity is declining rapidly on every continent and in every major river basin on Earth, and this degradation is occurring more rapidly than in terrestrial ecosystems. Currently, about one third of all global freshwater discharges pass through human agricultural, industrial or urban infrastructure. About one fifth of the Earth’s arable land is now already equipped for irrigation, including all the most productive lands, and this proportion is projected to surpass one third by midcentury to feed the rapidly expanding populations of humans and commensal species, especially poultry and ruminant livestock. Less than one fifth of the world’s preindustrial freshwater wetlands remain, and this proportion is projected to decline to under one tenth by midcentury, with imminent threats from water transfer megaprojects in Brazil and India, and coastal wetland drainage megaprojects in China. The Living Planet Index for freshwater vertebrate populations has declined to just one third that of 1970, and is projected to sink below one fifth by midcentury. A linear model of global economic expansion yields the chilling prediction that human utilization of critical freshwater resources will approach one half of the Earth’s total capacity by midcentury. Although the magnitude and growth of the human freshwater footprint are greater than is generally understood by policy makers, the news media, or the general public, slowing and reversing dramatic losses of freshwater species and ecosystems is still possible. We recommend a set of urgent policy actions that promote clean water, conserve watershed services, and restore freshwater ecosystems and their vital services. Effective management of freshwater resources and ecosystems must be ranked amongst humanity’s highest priorities.
Studying the capacity of some plant species to adapt to climate change is essential for ecological research and agricultural policy development. Chinese Torreya (Torreya grandis ‘Merrillii’) has been an important crop tree in subtropical China for over a thousand years. It is necessary to characterize its adaptation to climate change. In this study, the average monthly temperature and precipitation from 1901 to 2017 in the six regions with Chinese Torreya plantations at different provinces were analyzed. The results indicated that the average annual air temperature across these regions had increased by about 2.0 °C, but no general trend in the annual precipitation and incidence of drought was found. The annual air temperature that Chinese Torreya plantations had experienced was 12.96–18.23 °C; the highest and the lowest average monthly air temperatures were 30.1 °C and −0.8 °C, respectively. The lowest and the highest annual precipitation were 874.56 mm and 2501.88 mm, respectively. Chinese Torreya trees endured a severe drought period in the 1920s. The monthly air temperature at Zhuji, which is the central production region, showed a significant correlation with the air temperature in the other five regions. The monthly precipitation in Hunan and Guizhou had no significant correlation with that of Zhuji. Chinese Torreya plantations have been grown in the regions with a similar climate distance index of air temperatures but different precipitation. This tree has a high capacity to adapt to climate change based on the climate dynamics across its range. This approach may provide a way to evaluate climate adaptation in other tree species. These results may provide helpful information for the development of Chinese Torreya plantations.
Climate change, with increased temperatures and varied rainfall, poses a great challenge to food security around the world. Appropriately assessing the impacts of climate change on crop productivity and understanding the adaptation potential of agriculture to climate change are urgently needed to help develop effective strategies for future agriculture and to maintain food security. In this study, we studied future maize yield changes under 1.5 °C (2018–2037) and 2 °C (2044–2063) warming scenarios and investigated the adaptation potential across China's Maize Belt by optimizing the sowing date and cultivar using the APSIM-Maize model. In comparison to the baseline scenario, under the 1.5 °C and 2 °C warming scenarios, we found that without adaptation, maize yields would increase in the relatively cool regions with a single-cropping system but decrease in other regions. However, in comparison with the baseline scenario, under the 1.5 °C and 2 °C warming scenarios with adaptation, maize yields would increase by 11.1%–53.9% across the study area. Across the maize belt, compared with the baseline scenario, under warming of 1.5 °C, the potential sowing window would increase by 2–17 d, and under warming of 2 °C, this sowing window would increase by 4–26 d. The optimal sowing window would also be significantly extended in the regions with single-cropping systems by an average of 10 d under the 1.5 °C warming scenario and 12 d under the 2 °C warming scenario. Late-maturing cultivar achieved higher yield than early-middle maturing cultivars in all regions except the north part of Northeast China. Adjusting the sowing date by increasing growth-period precipitation contributed more (44.5%–96.7%) to yield improvements than shifting cultivars (0%–50.8%) and climate change (−53.1% to 23.0%) across all maize planting regions except in the wet southwestern parts of the maize belt. The differences among the maize planting regions in terms of high adaptation potential provide invaluable information for policymakers and stakeholders of maize production to set out optimized agricultural strategies to safeguard the supply of maize.
There is pressing need to anticipate the impacts of climate change on species and their functional contributions to ecosystem processes. Our objective is to evaluate the potential bee response to climate change considering (1) response traits—body size, nest site, and sociality; (2) contributions to ecosystem services (effect trait)—crop pollination; and (3) bees’ size of current occurrence area. We analyzed 216 species occurring at the Carajás National Forest (Eastern Amazon, Pará, Brazil), using two different algorithms and geographically explicit data. We modeled the current occurrence area of bees and projected their range shift under future climate change scenarios through species distribution modeling. We then tested the relationship of potential loss of occurrence area with bee traits and current occurrence area. Our projections show that 95% of bee species will face a decline in their total occurrence area, and only 15 to 4% will find climatically suitable habitats in Carajás. The results indicate an overall reduction in suitable areas for all traits analyzed. Bees presenting medium and restricted geographic distributions, as well as vital crop pollinators, will experience significantly higher losses in occurrence area. The potentially remaining species will be the wide-range habitat generalists, and the decline in crop-pollinator species will probably pose negative impact on pollination service. The north of Pará presented the greatest future climatic suitability and can be considered for conservation purposes. These findings emphasize the detrimental effects on biodiversity and agricultural production by climate change and provide data to support conservation planning.
Eutrophication, global warming, and rising carbon dioxide (CO2) levels are the three most prevalent pressures impacting the biosphere. Despite their individual effects are well-known, it remains untested how oligotrophication (i.e. nutrients reduction) can alter the planktonic community responses to warming and elevated CO2 levels. Here, we performed an indoor mesocosm experiment to investigate the warming × CO2 interaction under a nutrient reduction scenario (40%) mediated by an in-lake management strategy (i.e. addition of a commercial solid-phase phosphorus sorbent -Phoslock®) on a natural freshwater plankton community. Biomass production increased under warming × CO2 relative to present-day conditions; however, a Phoslock®-mediated oligotrophication reduced such values by 30-70%. Conversely, the warming × CO2 × oligotrophication interaction stimulated the photosynthesis by 20% compared to ambient nutrient conditions, and matched with higher resource use efficiency (RUE) and nutrient demand. Surprisingly, at a group level, we found that the multi-stressors scenario increased the photosynthesis in eukaryotes by 25%, but greatly impaired in cyanobacteria (ca. -25%). This higher cyanobacterial sensitivity was coupled with a reduced light harvesting efficiency and compensation point. Since Phoslock®-induced oligotrophication unmasked a strong negative warming × CO2 effect on cyanobacteria, it becomes crucial to understand how the interplay between climate change and nutrient abatement actions may alter the, ecosystems functioning. With an integrative understanding of these processes, policy makers will design more appropriate management strategies to improve the ecological status of aquatic ecosystems without compromising their ecological attributes and functioning.
Fire is a complex Earth system phenomenon that fundamentally affects vegetation distributions, biogeochemical cycling, climate, and human society across most of Earth's land surface. Fire regimes are currently changing due to multiple interacting global change drivers, most notably climate change, land use, and direct human influences via ignition and suppression. It is therefore critical to better understand the drivers, patterns, and impacts of these changing fire regimes now and continuing into the future. Our review contributes to this focus issue by synthesizing results from 27 studies covering a broad range of topics. Studies are categorized into (i) Understanding contemporary fire patterns, drivers, and effects; (ii) Human influences on fire regimes; (iii) Changes in historical fire regimes; (iv) Future projections; (v) Novel techniques; and (vi) Reviews. We conclude with a discussion on progress made, major remaining research challenges, and recommended directions.
Although extinctions due to climate change are still uncommon, they might surpass those caused by habitat loss or overexploitation over the next few decades. Among marine megafauna, mammals fulfill key and irreplaceable ecological roles in the ocean, and the collapse of their populations may therefore have irreversible consequences for ecosystem functioning and services. Using a trait-based approach, we assessed the vulnerability of all marine mammals to global warming under high and low greenhouse gas emission scenarios for the middle and the end of the 21st century. We showed that the North Pacific Ocean, the Greenland Sea and the Barents Sea host the species that are most vulnerable to global warming. Future conservation plans should therefore focus on these regions, where there are long histories of overexploitation and there are high levels of current threats to marine mammals. Among the most vulnerable marine mammals were several threatened species, such as the North Pacific right whale (Eubalaena japonica) and the dugong (Dugong dugon), that displayed unique combinations of functional traits. Beyond species loss, we showed that the potential extinctions of the marine mammals that were most vulnerable to global warming might induce a disproportionate loss of functional diversity, which may have profound impacts on the future functioning of marine ecosystems worldwide.
Impacts of climate change like global warming, drought, flooding, and other extreme events are posing severe challenges to global crop production. Contribution of Brassica napus towards the oilseed industry makes it an essential component of international trade and agroeconomics. Consequences from increasing occurrences of multiple abiotic stresses on this crop are leading to agroeconomic losses making it vital to endow B. napus crop with an ability to survive and maintain yield when faced with simultaneous exposure to multiple abiotic stresses. For an improved understanding of the stress sensing machinery, there is a need for analyzing regulatory pathways of multiple stress-responsive genes and other regulatory elements such as non-coding RNAs. However, our understanding of these pathways and their interactions in B. napus is far from complete. This review outlines the current knowledge of stress-responsive genes and their role in imparting multiple stress tolerance in B. napus. Analysis of network crosstalk through omics data mining is now making it possible to unravel the underlying complexity required for stress sensing and signalling in plants. Novel biotechnological approaches such as transgene-free genome editing and utilization of nanoparticles as gene delivery tools are also discussed. These can contribute to providing solutions for developing climate change resilient B. napus varieties with reduced regulatory limitations. The potential ability of synthetic biology to engineer and modify networks through fine-tuning of stress regulatory elements for plant responses to stress adaption is also highlighted.
Despite their limited spatial extent, freshwater ecosystems host remarkable biodiversity, including one third of all vertebrate species. This biodiversity is declining dramatically: globally, wetlands are vanishing three times faster than forests, and freshwater vertebrate populations have fallen more than twice as steeply as terrestrial or marine populations. Threats to freshwater biodiversity are well documented but co-ordinated action to reverse the decline is lacking. We present an Emergency Recovery Plan to “bend the curve” of freshwater biodiversity loss. Priority actions include: 1) accelerating implementation of environmental flows; 2) improving water quality; 3) protecting and restoring critical habitats; 4) managing exploitation of freshwater ecosystem resources, especially species and riverine aggregates; 5) preventing and controlling non-native species invasions; and 6) safeguarding and restoring river connectivity. We recommend adjustments to targets and indicators for the Convention on Biological Diversity and the Sustainable Development Goals, and roles for national and international state and non-state actors.
*** This paper has been accepted for publication in BioScience. A link to the BioScience version will follow in due course ***
Climate change is known to affect regional weather patterns and phenology; however, we lack understanding of how climate drives phenological change across local spatial gradients. This spatial variation is critical for determining whether subpopulations and metacommunities are changing in unison or diverging in phenology. Divergent responses could reduce synchrony both within species (disrupting gene flow among subpopulations) and among species (disrupting interspecific interactions in communities). We also lack understanding of phenological change in environments where life history events are frequently aseasonal, such as the tropical, arid, and semi-arid ecosystems that cover vast areas. Using a 33-year-long dataset spanning a 1,267-m semi-arid elevational gradient in the southwestern United States, we test whether flowering phenology diverged among subpopulations within species and among five communities comprising 590 species. Applying circular statistics to test for changes in year-round flowering, we show flowering has become earlier for all communities except at the highest elevations. However, flowering times shifted at different rates across elevations likely because of elevation-specific changes in temperature and precipitation, indicating diverging phenologies of neighboring communities. Subpopulations of individual species also diverged at mid-elevation but converged in phenology at high elevation. These changes in flowering phenology among communities and subpopulations are undetectable when data are pooled across the gradient. Furthermore, we show that nonlinear changes in flowering times over the 33-year record are obscured by traditional calculations of long-term trends. These findings reveal greater spatiotemporal complexity in phenological responses than previously recognized and indicate climate is driving phenological reshuffling across local spatial gradients.
In order to identification of salt tolerance genotype, an experiment with seven rapeseed cultivars under different levels of salt stress treatments (0,7 and 14 dsmG) has been undertaken using a factorial 1 experiment based on completely randomized design with four replications in greenhouse at Sari Agricultural Science and Natural Resources University (SANRU). During vegetative growth, shoot Na and K contents, + + K /Na ratio and grain yield corresponding with salinity susceptibility index (SSI) and salt tolerance index (STI) + + were measured. In general, tolerance cultivars (LSG2 and LSN) with higher agronomic performance, contained lower Na and higher K and K /Na ratio than in tolerance cultivars (Sarigol and RGS003). Shoot Na contents + + + + + showed negative correlation with grain yield (r =-0.384, p<0.05) and STI (r =-0.392, p<0.01) but positive correlation with SSI(r = 0.406, p<0.01). These two indices have been considered as useful criteria for screening of tolerance cultivars under salt stress. Key word: CANOLA cultivars screening % Salt tolerance % K % Na % STI % SSI + +
Enhanced greenhouse effects by anthropogenic emissions of greenhouse gases (GHGs) resulted in global warming since the Industrial Revolution. However, the influence of the spectral characteristics of the Earth's surface radiation on the greenhouse effect has not been completely explored. This work uses the surface temperature as the variable of model and investigates the response mechanism of the greenhouse effect. According to the GHGs' different selective spectral absorption of earth's infrared radiation (IR) band and the distribution characteristic of spectral radiant intensity with the temperature increases, some quantified analysis shows that the greenhouse effect is highly dependent on two factors: the radiation intensity enhancement (RIE) and the spectral absorption enhancement (SAE). RIE is determined by the spectral radiant intensity of earth's IR while SAE represents the GHGs' spectral absorption change under different wavelength. As the results show, RIE always enhances the greenhouse effect, while SAE, as a result of the spectral shift in the Earth's radiant energy, can enhance or weaken the greenhouse effect depending on the positive or negative total SAE integrated over the entire spectral region. The quantified data of this work also explain the reason why greenhouse effect has greater impact on extreme cold areas from the aspect of spectral characteristics: when the surface temperature drops below −20 °C, SAE of CO2 has an enhancing effect, so that both RIE and SAE exert positive influences with the temperature increase in the polar region for its extremely low surface temperature, which doubly enhances the global warming.
Drought stress, especially at the reproductive stage, is a major limiting factor that compromises the productivity and profitability of canola in many regions of the world. Improved genetics for drought tolerance would enable the identification and development of resilient cultivars, resulting in increased canola production. The main objective of the present study was to dissect the genetic basis of seed yield of canola under water-limited conditions. A doubled haploid population derived from a cross between two Australian parental lines, RP04 and Ag-Outback, was evaluated to identify the genetic variation in fractional normalised deviation vegetative index (NDVI), aboveground shoot biomass accumulation, flowering time and plasticity in seed yield under irrigated and rainfed field conditions in two consecutive years. An irrigation treatment was applied at the 50% flowering stage and an incremental drought tolerance index (DTI) was estimated for seed yield. By utilising a genetic linkage map based on 18851 genome-wide DArTseq markers, we identified 25 genomic regions significantly associated with different traits (logarithm of odds (LOD) ≥ 3), accounting for 5.5–22.3% of the genotypic variance. Three significant genomic regions on chromosomes A06, A10 and C04 were associated with DTI for seed yield. Some of the quantitative trait loci (QTL) were localised in the close proximity of candidate genes involved in traits contributing to drought escape and drought avoidance mechanisms, including FLOWERING LOCUS T (FT) and FLOWERING LOCUS C (FLC). Trait-marker associations identified herein can be validated across diverse environments, and the sequence-based markers may be used in a marker assisted selection breeding strategy to enhance drought tolerance in canola breeding germplasm.
Ecological processes, such as migration and phenology, are strongly influenced by climate variability. Studying these processes often relies on associating observations of animals and plants with climate indices, such as the El Niño–Southern Oscillation (ENSO). A common characteristic of climate indices is the simultaneous emergence of opposite extremes of temperature and precipitation across continental scales, known as climate dipoles. The role of climate dipoles in shaping ecological and evolutionary processes has been largely overlooked. We review emerging evidence that climate dipoles can entrain species dynamics and offer a framework for identifying ecological dipoles using broad-scale biological data. Given future changes in climatic and atmospheric processes, climate and ecological dipoles are likely to shift in their intensity, distribution, and timing.
Climate change is predicted to increase the severity and prevalence of harmful algal blooms (HABs). In the past twenty years, omics techniques such as genomics, transcriptomics, proteomics and metabolomics have transformed that data landscape of many fields including the study of HABs. Advances in technology have facilitated the creation of many publicly available omics datasets that are complementary and shed new light on the mechanisms of HAB formation and toxin production. Genomics have been used to reveal differences in toxicity and nutritional requirements, while transcriptomics and proteomics have been used to explore HAB species responses to environmental stressors, and metabolomics can reveal mechanisms of allelopathy and toxicity. In this review, we explore how omics data may be leveraged to improve predictions of how climate change will impact HAB dynamics. We also highlight important gaps in our knowledge of HAB prediction, which include swimming behaviors, microbial interactions and evolution that can be addressed by future studies with omics tools. Lastly, we discuss approaches to incorporate current omics datasets into predictive numerical models that may enhance HAB prediction in a changing world. With the ever-increasing omics databases, leveraging these data for understanding climate-driven HAB dynamics will be increasingly powerful.
Thresholds of aridity
Increasing aridity due to climate change is expected to affect multiple ecosystem structural and functional attributes in global drylands, which cover ∼45% of the terrestrial globe. Berdugo et al. show that increasing aridity promotes thresholds on the structure and functioning of drylands (see the Perspective by Hirota and Oliveira). Their database includes 20 variables summarizing multiple aspects and levels of ecological organization. They found evidence for a series of abrupt ecological events occurring sequentially in three phases, culminating with a shift to low-cover ecosystems that are nutrient- and species-poor at high aridity values. They estimate that more than 20% of land surface will cross at least one of the thresholds by 2100, which can potentially lead to widespread land degradation and desertification worldwide.
Science , this issue p. 787 ; see also p. 739
Much of our existing knowledge of Middle Jurassic paleoclimate is based on well-dated marine isotopic records that show fluctuations between warm (greenhouse effected) and cool climates. In contrast, much less is known from contemporaneous terrestrial deposits that are often difficult to correlate stratigraphically with marine successions, and are typically considered as showing regional rather than global signals. In this paper we show that the carbon-isotopic, petrological and floral record through 20 m thick coals in the Northern Qaidam Basin (NW, China) represents a relatively comprehensive northern hemisphere Bajocian (Middle Jurassic) record for terrestrial climatic change. δ¹³Ccoal values for 88 samples from the Yuqia area in Northern Qaidam Basin range from–25.3‰ to –22.5‰, indicating that C3 plants were the main coal-forming vegetation in the region during the Middle Jurassic. This isotopic variation follows fluctuations in the composition of ferns and gymnosperms, where higher ratios correspond to more negative δ¹³C values. The similar carbon isotope values of gymnosperms and coal from the Yuqia area indicate that the coal comprises a high proportion of organic material derived from gymnosperm taxa, which is consistent with the very high abundance of diterpenoids in coal and especially pimarane and abietane that are produced primarily by gymnosperms. Results from the coal matrix provide an opportunity to record paleoclimate changes, showing several striking and regular coal-forming cycles with distinct long- and short-term variations. Trends of δ¹³Ccoal values changes coupled with the evolution of coal-forming plants may record a gradual increase in paleo-CO2 (pCO2) concentration, water-table level changes and the decrease in abundance of Classopollis conifer pollen through Bajocian. This result is in accordance with the published marine carbonate records for this time, with correlation enabled through matching carbon isotope curves from the terrestrial succession at Yuqia and marine records. The similarity of the terrestrial and marine geochemical and floral record is an indication that the observed paleoclimate signal is a global phenomenon. Furthermore, the high-frequency fluctuation of δ¹³Ccoal values, along with the coal petrologic variations may record short-term changes of environmental factors (e.g. temperature or humidity/precipitation), especially during intervals when palaeobotanical composition has not fluctuated intensely.
Freshwater ecosystems are among the most endangered ecosystems on Earth and are vulnerable to climate change. Studies have shown that climate change has already altered the phenology and distribution of freshwater species. However, there are still major gaps in our understanding of potential impacts of climate change on freshwater ecosystems and their organisms. Freshwater fishes were used as effective indicators for identifying the degree, direction and scale of changes in aquatic ecosystems and as indicators of freshwater ecosystem quality and health. However, they are rarely used to determine sensitive freshwater ecosystems to climate change using species distribution modeling. We modeled current and future distribution of 15 endemic freshwater fish in Iran to identify winners and losers of climate change and high priority rivers for conservation under climate change. In addition, we assessed changes in elevational distribution of the species under climate change. Our results showed that five species will lose some parts of their current suitable range under climate change while ten species will gain new suitable habitats. Considering their restricted range, endemic species are of special conservation concern, so results of this study can be used for conservation of endemic freshwater fishes. Species which were identified to be negatively affected by climate change should be prioritized for monitoring and conservation and can be the subject of future conservation programs. Using the five species for which reductions of range size were predicted, 20 rivers were identified as targets of future conservation actions to reduce negative impacts of climate change on freshwater fish.
A failure to recognize the factors behind continued emissions growth could limit the world’s ability to shift to a pathway consistent with 1.5 °C or 2 °C of global warming. Continued support for low-carbon technologies needs to be combined with policies directed at phasing out the use of fossil fuels.