Gradual Warming Research Articles

Response of native and invasive grazers to global warming: marine heatwaves vs. gradual trends

Ecological responses to global warming are likely driven by a combination of gradual warming trends and extreme climate events, which are increasing in frequency and intensity. Specifically, heatwaves may amplify the impact of ongoing warming, and thus affect species’ physiological responses, behaviour and eventually survival. Here, we tested the hypothesis that a tropical invasive grazer snail, Cerithium scabridum, will be more resilient to the effects of future gradual warming and marine heatwaves (MHWs) than its native congener C. lividulum, co-occurring in rocky intertidal pools along the Levantine coast. Survival and faecal production (as a proxy for feeding rate) of the 2 species were measured under 4 experimental temperature conditions: ambient summer mean (31°C), predicted warming scenario (ambient +3°C), and short-term MHWs (+5°C) added to either ambient or warming treatments, followed by a recovery period. No effect of warming alone was detected on either species, whereas MHW reduced faecal production only in the native C. lividulum. During the recovery period, C. lividulum survival dropped, but the few surviving individuals recovered from the heat stress as indicated by the increase in faecal production. Neither snail species survived under the combination of warming and MHW. These results suggest that both species, living in a thermally fluctuating and often extreme environment, can tolerate a +3°C gradual warming, but only the invasive snail can withstand a +5°C heatwave. However, neither species can endure a severe heatwave on top of predicted gradual warming, potentially leading to population collapse among both species in the region.

Climatic and environmental changes since last deglaciation in the steppe region of northern China and their impact on early population survival patterns

The northern Chinese steppe is situated in the periphery of the East Asian Summer Monsoon and exhibits high sensitivity to variations in monsoon intensity and global climate change. Therefore, comprehending the climatic evolution history of this region is pivotal for elucidating early human civilization development. The research focuses on a fully enclosed crater lake located in the northern Chinese steppe by utilizing n-alkanes, total organic carbon (TOC), total nitrogen (TN) in lake sediments, based on AMS-14C dating analysis, the climatic and environmental evolution history of this region from the last deglaciation to the middle Holocene has been reconstructed, and the impact of climate change on the evolution of early human civilization is elucidated. The findings indicate that the EASM driven by summer solar radiation, exerts control over the climate and hydrology in the steppe region of northern China. Since the last deglaciation, the gradual warming and humidification of the climate environment have significantly enhanced the animal and plant resources, thereby establishing a solid foundation for the transition of early human populations in northern Chinese steppe from high-mobility hunter-gatherers to settled communities. Additionally, this climatic shift has provided an optimal backdrop for the emergence of primitive agriculture. The changes of stone tool assemblages unearthed at related sites also confirm the above views. However, the climate model underwent rapid changes during the period of 7.2–6.4 cal kyr BP, leading to the occurrence of extreme arid climate events. Consequently, regional precipitation decreased, lake ecology became imbalanced, woody plants retreated in the basin, and vegetation coverage was greatly reduced. The aforementioned factor may have played a pivotal role in the disappearance of early populations within the region. Consequently, climate and environmental change not only serve as the primary driving force behind human civilization’s development but also act as an inexorable catalyst for its decline.

Long‐Term Stability of Marine Forests Facing Moderate Gradual Warming in a Remote Biodiversity Hotspot

ABSTRACTAimOcean warming and marine heatwaves are rapidly reconfiguring the composition of seaweed forests—the world's largest coastal vegetated biome. Seaweed forest responses to climate change in remote locations, which constitute the majority of the forest biome, remain however poorly quantified. Here, we examine the temporal stability of the seaweed forests across a global seaweed biodiversity hotspot where several species are predicted to undergo severe range contractions in this century.LocationWestern south coast of Australia.MethodsSeaweed forest canopies were censused at 18 shallow (< 10 m) sheltered reefs between 1997 and 2006 and again between 2021 and 2024 (six sites per location). We also surveyed 24 sites to examine whether temporal changes differed over gradients of wave exposure and depth.ResultsSeaweed forest canopies across all locations showed surprisingly little change in biomass, cover, stand density and species composition over two decades, with strong spatial structuring across depth and exposure gradients persisting over time. The average thermal affinity of forest canopies (i.e., the community temperature index, CTI) did not track warming, suggesting that factors other than temperature (e.g., wave exposure and depth) are more important drivers of forest stand structure and/or that key thermal thresholds have not yet been crossed. Forests in the location with the most pronounced warming exhibited increased thermal bias over time (total bias of 0.8°C–2.2°C), indicating they were dominated by species with cooler affinities than their local temperatures.Main ConclusionsThe greater thermal bias in forests at the warmer edge of southern Australia suggests these will be more susceptible to future warming‐related compositional changes than forests in cooler locations. The relative stability we found contrasts with a current context of rapidly changing seaweed forests nationally and globally, highlighting the need to deepen our ecological understanding of the region so that future changes to its unique biodiversity and ecosystem services can be predicted and mitigated.

Radiocarbon dating of the natural groundwater in the Ob-Zaisan folded region (Russia)

Groundwater in the Ob-Zaisan folded region (Russia) has significant differences in the stable isotope composition of oxygen and hydrogen, which cannot be explained by the geographical and relief features of the region. A probable reason for these differences could be climatic changes in the study area over the past tens of thousands of years. The method of the radiocarbon dating can be perfectly suited in order to determine such small geological ages. The dating of waters using 14C data gives an understanding of their residence time. It will make it possible to differentiate periods of recharge and accumulation of water in aquifers and track the changes of the water stable isotope composition over time. The estimated water age ranges from 650 to 19,000 years. The enrichment of δD and δ18O values with the decreasing of the water age indicates a gradual warming of the Novosibirsk region climate. These results logically complement the meteorological observations over the last century and may be useful for paleoclimate reconstructions of the region.

Tropical Andean climate variations since the last deglaciation

Global warming during the Last Glacial Termination was interrupted by millennial-scale cool intervals such as the Younger Dryas and the Antarctic Cold Reversal (ACR). Although these events are well characterized at high latitudes, their impacts at low latitudes are less well known. We present high-resolution temperature and hydroclimate records from the tropical Andes spanning the past ~16,800 y using organic geochemical proxies applied to a sediment core from Laguna Llaviucu, Ecuador. Our hydroclimate record aligns with records from the western Amazon and eastern and central Andes and indicates a dominant long-term influence of changing austral summer insolation on the intensity of the South American Summer Monsoon. Our temperature record indicates a ~4 °C warming during the glacial termination, stable temperatures in the early to mid-Holocene, and slight, gradual warming since ~6,000 y ago. Importantly, we observe a ~1.5 °C cold reversal coincident with the ACR. These data document a temperature change pattern during the deglaciation in the tropical Andes that resembles temperatures at high southern latitudes, which are thought to be controlled by radiative forcing from atmospheric greenhouse gases and changes in ocean heat transport by the Atlantic meridional overturning circulation.

The use of time-dynamic patterns of temperature and flexible generalized models to clarify the relations between temperature and semen quality

BackgroundSperm quality has decreased over the last decades worldwide. It is affected, among others, by season and heat. This study aimed to address the association between ambient temperature and sperm quality by assessing its shape using flexible multivariate models and identifying distinct time-dynamic patterns of temperature change based on unsupervised analysis. Material and methodsA retrospective population-based study has been conducted, including all samples of males attending the Fertility and In-Vitro-Fertilization unit at a single medical center during 2016–2022. Flexible generalized models were fitted to characterize the relations between sperm quality and temperature while accounting for patients characteristics, and to identify temperature levels that correspond with the optimal sperm quality. This information was then used to estimate adjusted slope coefficients at specified time-windows. ResultsIn total, 4555 sperm samples were provided by 3229 individuals. Sperm concentration, motility and progressive motility were higher by 8 %, 11 % and 16 %, respectively, during the spring versus the fall season. Furthermore, their quality during early spermatogenesis improved with temperature, until a certain optimum around 23 °C–24 °C. Increasing temperature at later developmental stages was associated with lower sperm concentration and higher motility. Sperm concentration and motility were highest following a period of moderate gradual warming. Motility was higher and sperm concentration was lower, following a period with heatwaves or summer. ConclusionsThis study assessed temperature role in sperm production quality by considering both average and time-dynamic temperatures. It identified several temperature change patterns over time and stratified the analysis by them. The differences in the relations across stages of spermatogenesis were addressed. Several mechanisms may explain the associations found, including heat-induced apoptosis of the sperm cells, and destruction of sperm cells DNA integrity by over-production of reactive oxygen species. The gradual global warming necessitates exploration of individual response to outdoor temperature in relations to genetic predisposition, lifestyle, and other health characteristics.

Temporal variability of sea surface temperature affects marine macrophytes range retractions as well as gradual warming

Record mean sea surface temperatures (SST) during the past decades and marine heatwaves have been identified as responsible for severe impacts on marine ecosystems, but the role of changes in the patterns of temporal variability under global warming has been much less studied. We compare descriptors of two time series of SST, encompassing extirpations (i.e. local extinctions) of six cold-temperate macroalgae species at their trailing range edge. We decompose the effects of gradual warming, extreme events and intrinsic variability (e.g. seasonality). We also relate the main factors determining macroalgae range shifts with their life cycles characteristics and thermal tolerance. We found extirpations of macroalgae were related to stretches of coast where autumn SST underwent warming, increased temperature seasonality, and decreased skewness over time. Regardless of the species, the persisting populations shared a common environmental domain, which was clearly differentiated from those experiencing local extinction. However, macroalgae species responded to temperature components in different ways, showing dissimilar resilience. Consideration of multiple thermal manifestations of climate change is needed to better understand local extinctions of habitat-forming species. Our study provides a framework for the incorporation of unused measures of environmental variability while analyzing the distributions of coastal species.

Embryonic and larval development of yellow perch (Perca flavescens) and its sensitivity to incubation temperature.

The ontogenetic development in teleost fish is sensitive to temperature, and the developmental rate has a direct relationship with the environmental temperature within a species' thermal tolerance limit. Temperature determines time to and survival at hatching. Yellow perch is a North American species of ecological and commercial importance, and its phenology is vulnerable to climate change. The embryonic development of yellow perch was comparable to closely related members of the family Percidae. Developmental progression was fastest at 18°C and slowest at 12°C, with medial progression at 15°C. Time to hatch and swim-up, feeding onset, and exogenous feeding phases were different across all incubation temperatures regardless of a gradual post-hatch warming of the 12 and 15°C groups to a common garden temperature of 18°C. Incubation temperature may lower the rate of survival to hatch at 15°C and had complex impacts on developmental abnormalities. Temperature had significant effects on the development rate, time of hatch, survival, and incidence of developmental abnormalities. Early ontogenetic thermal history in ectotherms is an important factor determining phenotypic variation. It will be important to link the thermally induced changes in development described here to the physiological and morphological differences and to link the developmental abnormalities to functional performance.

Seasonal dynamics of global marine heatwaves over the last four decades

Marine heatwaves (MHWs), prolonged periods of abnormally high sea temperature, have greater devastating impacts on marine ecosystem services and socioeconomic systems than gradual long-term ocean warming. Despite growing evidence of increases in MHW frequency, duration, and intensity, their interseasonal variations remain unclear. Using satellite-derived daily sea surface temperature (SST) data from 1982 to 2022, this work reveals a strong seasonality in MHWs. Typically, the highest cumulative intensity, characterizing total impacts on ecosystems, occurs during the local warm seasons in most oceans, leading to a significant interseasonal difference between warm and cold seasons. The interseasonal difference is predominantly driven by air-sea heat flux, rather than oceanic horizontal advection and vertical process. An increase in these interseasonal differences is observed in mid and high latitudes, with a significant increase in the warm season and a weaker trend in the cold season. In the Equatorial Pacific and Western Equatorial Indian Ocean, intense MHWs are primarily exacerbated by the El Niño-Southern Oscillation (ENSO), which also determines interseasonal variations in MHWs. Understanding the seasonality of MHWs can help better formulate corresponding policies to reduce economic and ecological losses caused by these events and can improve the accuracy of future predictions.

Intraspecific Trait Variation Regulates Biodiversity and Community Productivity of Shrublands in Drylands

Intraspecific variation (Intra-V) has played an important role in determining the responses of ecosystem functions to climate change. However, its specific role in the regulation of ecosystem functions during community assembly is less investigated. In this study, we conducted a transect survey in northwest China and determined different plant functional types, namely resource-conservative, medium, and resource-acquisitive strategies, which describe resource-use strategies of plants in multi-functional dimensions. Plant functional traits including canopy, wood density (WD), height, specific leaf area (SLA), and leaf nitrogen (N) and phosphorus (P) concentrations were determined. Ecological filters, including external filtering (assembly processes at the regional scale), internal filtering (assembly processes within a certain community), and functional redundancy, were employed to examine plant environment interactions. We found that with the decrease in environmental pressure, dominant shrub plants changed from conservative to acquisition species in drylands. Specifically, a benign environment (such as stable and adequate precipitation, loose soil, and increased acid deposition) significantly increased plant mean traits, such as SLA and WD of shrubs, especially for conservative strategy plants. In addition, a benign environment mainly reduced the functional redundancy of SLA (FRedSLA) by strengthening internal filtering and, ultimately, increased aboveground biomass but decreased species richness. Our results suggest that conservative strategy plants with stronger adaptability to the external environment may exhibit more competitive advantages and play a more important role in community construction under future climate scenarios of gradual warming and wetting in northwest China. Our results also revealed that trait-based Intra-V may be a more reasonable ecological filter than plant mean traits for predicting the structure and function of dryland ecosystems.

Effects of Different Land Use Types on Surface Temperature in the Northwest Arid Zone

This study analyzed the spatial and temporal characteristics of surface temperature in Uttarakhand Banner, and explored the correlation between land use types and surface temperature. The results show that the surface temperature of Urumqi Banner is greatly influenced by the change of land use types, and the difference of surface temperature between different land use types is obvious; the spatial and temporal trend of surface temperature in Urumqi Banner is different from the trend of gradual warming of the global climate change, which is mainly due to the change of the land use types by human activities.

Abrupt warming and alpine glacial retreat through the last deglaciation in Alaska interrupted by modest Northern Hemisphere cooling

Abstract. Alpine glacier-based temperature reconstructions spanning the last deglaciation provide critical constraints on local to regional climate change and have been reported from several formerly glaciated regions around the world yet remain sparse from high-northern-latitude regions. Using newly and previously 10Be-dated moraines, we report paleo-glacier equilibrium line altitudes (ELAs) for 15 time slices spanning the Last Glacial Maximum (LGM) to the Little Ice Age (LIA) for a valley in the western Alaska Range. We translate our ELA reconstructions into a proxy for summer temperature by applying a dry adiabatic lapse rate at each reconstructed ELA relative to the outermost LIA moraine. We observe ∼4 °C warming through the last deglaciation at our site that took place in two steps following initial gradual warming: ∼1.5 °C abrupt warming at 16 ka, ∼2 kyr after the onset of global CO2 rise, and ∼2 °C warming at ∼15 ka, near the start of the Bølling. Moraine deposition and modest summer cooling during Heinrich Stadial 1 and the early Younger Dryas (YD) suggest that despite these events being expressed more strongly in wintertime, the classic blueprint of North Atlantic climate variability extends to the western Arctic region.

Spontaneous Activation of the Pacific Meridional Overturning Circulation (PMOC) in Long-Term Ocean Response to Greenhouse Forcing

Abstract The present-day deep ocean global meridional overturning circulation is dominated by the Atlantic meridional overturning circulation (AMOC), with dense water sinking in the high-latitude North Atlantic Ocean. In contrast, deep-water formation in the subarctic North Pacific is inhibited by a strong upper-ocean halocline, which prevents the development of an analogous Pacific meridional overturning circulation (PMOC). Nevertheless, paleoclimate evidence suggests that a PMOC with deep-water formation in the North Pacific was active, for instance, during the warm Pliocene epoch and possibly during the most recent deglaciation. In the present study, we describe a spontaneous activation of the PMOC in a multimillennial abrupt 4 × CO2 experiment using one of the configurations of the Community Earth System Model (CESM1). Soon after the imposed CO2 increase, the model’s AMOC collapses and remains in a weakened state for several thousand years. The PMOC emerges after some 2500 years of integration, persists for about 1000 years, reaching nearly 10 Sv (1 Sv ≡ 106 m3 s−1), but eventually declines to about 5 Sv. The PMOC decline follows the AMOC recovery in the model, consistent with an Atlantic–Pacific interbasin seesaw. The PMOC activation relies on two factors: (i) gradual warming and freshening of the North Pacific deep ocean, which reduces ocean vertical stratification on millennial time scales, and (ii) upper-ocean salinity increase in the subarctic North Pacific over several centuries, followed by a rapid erosion of the pycnocline and activation of deep-water formation. Ultimately, our results provide insights on the characteristics of global ocean overturning in warm climates.

Yield stability of winter wheat in intercrop makes better adaptation to climate conditions

Global climate change is a main issue today. Negative effects, such as gradual warming, annual precipitation decrease and frequences of extreme meteorological events have also felt in Hungary. These effects significally tested the adaptive capacity of our cultivated plants. In our country two-thirds of the arable land is occupied by cereals. In most cases there is no crop rotation, pre-crop effect remains unused. Intercrop is a special kind of plant association, where two or more crops growing simultaneously on the same field. It can be increases resilience against pest and pesticides, provides better utilization of growth resources, and weed suppression. In mixture mitigate the effects of climate. Our experiments were made in 2020/2021 with 3 winter wheat varieties (GK Szilárd, Celulle, GK Csillag) and a winter pea variety (Aviron) in 4 repeats, on 10 square meter random layout plots in Szeged-Öthalom. We set 3 different seed density in every variety in every combination. Higher seed density of wheat makes higher yield regardless of pea, except of GK Csillag at 75% seed density of wheat and pea. Increasing pea ratio in mixture, wheat yield decreased. In contrast GK Szilárd and Cellule, their 75% and 100% mixture with 75% Aviron achieved higher wheat yield. Pure stands have shown better values than the combined ones, vice versa for GK Csillag: every seed density with 50% of Aviron gaves the highest wheat yield. Wheat and pea yield together gives the yield advantage what intercrop provides.

Characteristics of Lightning Activities over the Tibetan Plateau Based on Satellite Detection and Its Circulation Background Analysis

Based on the detection data obtained by the LMI (Lightning Mapping Imager)—China’s first satellite-based lightning observation payload—from 2018–2022, combined with the ERA5 (ECMWF Reanalysis v5) reanalysis data of the same period, the temporal and spatial characteristics of lightning activities over the Tibetan Plateau and its response to the atmospheric circulation background are studied in detail in this paper. Based on the LMI data, we obtained consistent and continuous long-time-series lightning observation data for the whole region of the plateau for the first time, and the results show that the lightning density in the Tibetan Plateau is much smaller than that in the central and eastern land regions of China (CELR) at the same latitude. Lightning activity was unevenly distributed over the plateau and had obvious seasonal variation characteristics. The monthly amount of lightning and its ratio in the total amount of lightning for the whole year show the characteristics of “increasing first and then decreasing”. Most lightning occurs in June and July, which is about a month earlier than that in the CELR. The amount of lightning fluctuated in May and decreased rapidly after August, which is consistent with the local convective thunderstorm season. The hourly lightning frequency at different altitudes over the Tibetan Plateau is consistent with local convections and unique topography, and it is closely related to the features of the local night rain. The results also reveal comparative features between lightning and the atmospheric circulation background on the plateau, such as the wind field, CAPE (convective available potential energy), temperature, and humidity at 500 hPa. In the context of global warming, the average temperature in the central and western regions of the plateau increased in the past five years. This shows that the Tibetan Plateau, as a summer heat source, has a gradual warming trend, and the corresponding convections and lightning activities are also increasing gradually. Lightning activities can be used as an indicator of DCSs (deep convective systems). This paper gives a more comprehensive understanding of the characteristics of lightning activities all over the Tibetan Plateau, especially in the western part of the plateau, which lacked ground-based lightning observation data before. In addition, it reveals the comparative features between the lightning activities and the circulation background over the plateau in the past five years, which is helpful for further understanding the contribution of lightning activities to the plateau’s climate change. It can provide some reference for monitoring and researching the severe convective weather over the Tibetan Plateau.

Branched GDGT source shift identification allows improved reconstruction of an 8,000-year warming trend on Sumatra

Branched Glycerol Dialkyl Glycerol Tetraethers (brGDGTs) in sedimentary archives are increasingly used for paleotemperature reconstructions due to their strong correlation with mean annual air temperature. However, environmental factors can influence the brGDGT producing bacterial community, potentially affecting the brGDGT-temperature relationship and introducing fundamental errors in reconstructions. Here we assess the reliability of the methylation index of brGDGTs (MBT′5ME) in sediments as a paleotemperature proxy by tracking provenance differences based on brGDGT fractional abundances in a short lake core, two peat cores and surface soils on Sumatra (n = 333 in total). Then, we attempt to reconstruct the Holocene paleotemperatures on Sumatra using the two peat cores. Our results indicate distinct brGDGT and H-shaped brGDGT (H-GDGT) compositions in soil, lake and peat environments, suggesting production by different bacterial communities. We introduce a new index, the isomerization of H-GDGTs (IRH) that can distinguish between these environments. In an 11,000-year long peat core from Diatas, we find that brGDGT composition changes are dominated by bacterial community shifts rather than temperature changes. In contrast, a core from the nearby Padang peatland can be robustly used for a brGDGT-based paleotemperature reconstruction since there are no signs of past environmental or brGDGT source shifts. The results from Padang indicate a gradual warming trend over the past 8,000 years, consistent with climate model simulations and nearby sea surface temperature reconstructions. However, current MBT′5ME calibrations yield larger warming trends compared to simulations and other proxy studies, suggesting the need for tropical and/or peat-specific brGDGT temperature calibrations. Our findings demonstrate the importance of assessing environmental shifts and bacterial source community changes when employing brGDGT paleothermometry. The methodological framework outlined in this study can be used in future research for reliable down-core brGDGT temperature reconstructions. Our proxy reconstruction over the past 8,000 years offers novel insights into the Holocene temperature evolution from a region with low climate seasonality.

Mid-Holocene climate-glacier relationship inferred from landforms and relict lake sequence, Southern Zanskar ranges, NW Himalaya

The geomorphological disposition of (para/peri) glacial landforms, elemental geochemistry, and optical chronology of the relict lake sediment in the Southern Zanskar ranges, northwest Himalaya are used to understand the relationship between glacial dynamics and the lake sedimentation during the mid-Holocene climate variability. Following the Last Glacial Maxima (LGM), pulsating deposition of outwash gravels until the early Holocene overwhelmed the Zanskar valley. The obstruction of Tsarap Chu (chu = river) by alluvial fans during the mid-Holocene led to the development of Padum Lake. In the present study, cirque glacier moraines representing three minor glacial advances were mapped along with sedimentological details and dated using Optically Stimulated Luminescence (OSL) dating technique. The oldest cirque glacier advance - Padum Cirque moraine-3 (PDCm-3) is dated to 11.4 ± 0.9 ka. The succeeding advance (PDCm-2) is dated to 5.3 ± 0.6 and 4.8 ± 0.8 ka whereas, the younger cirque glacier advance (PDCm-1) remains undated. The mid to late Holocene climate variability inferred using major and trace element geochemistry of the relict Padum lake sediments supported by optical chronology indicates six centennial to millennial-scale climatic phases. The prominent warmer phases are represented by decreased mineralogical fine grain flux (low K/Ti, Fe/Si, and Al/Si) with a corresponding increased coarse grain flux (higher Ti/Al and Sr/Al ratios). These phases are dated between 5.9 and 5.5 ka (phase-I), 3.8 and 3.4 ka (phase-IV), and 2.8 and 2.5 ka (phase-VI). The increased mineralogical finer fraction (higher K/Ti, Fe/Si, and Al/Si) between 5.5 and 5.1 ka (phase-II) and 3.4 and 2.8 ka (phase-V) indicate reduced meltwater flux during cooler phases. The intervening phase-III (5.1–3.8 ka) is characterized by increased mineralogical coarse grain flux (decreasing K/Ti, Fe/Si, Al/Si) suggesting gradual warming. The oscillatory climate at millennial scale was further used to understand glacier dynamics. The PDCm-2 advance in the lake record corresponds to the first major cooling (5.5 and 5.1 ka; phase-II) and continued until ∼3.8 ka. Using geochemical data of lake record, a major recession is inferred after 3.8 ka that persisted until around 3.4 ka (phase-IV). Similarly, the undated younger cirque glacier advance (PDCm-1) is assigned to the second cooling event (3.4 and 2.8 ka; phase-V). Thereafter, the cirque glaciers receded, most likely under increasing dryness and fluctuating climate (2.8–2.5 ka, phase-VI). After ∼2.6 ka, the development of ice-wedge pseudomorphs indicates the onset of permafrost conditions that degraded after ∼2.5 ka implying an increase in air temperature. The lake sedimentation terminates with the deposition of multiple younger alluvial fan facies. The climate variability shows a close correspondence with regional climate records suggesting that marginal glacier advancements were triggered by enhanced moisture via atmospheric rivers and cooler winter temperatures. The study highlights the potential of relict lake sediment in association with para- and peri-glacial landforms to reconstruct the pattern of minor glacier responses to climate variability during the Holocene.

Effect of mineral fertilizers on the formation of the structure indicators of grain sorghum yield capacity

In the process of gradual warming, producers carry out the search of the crops, which develop high productivity of excellent quality grain in the difficult soil-climatic conditions. Grain sorghum is one of these crops. Similar to any other agricultural crop, its productivity depends on the effect of numerous factors including the elements of the cultivation technology. One of these elements is the application of mineral fertilizers. The purpose of the research was to study the effect of the plant mineral nutrition on the formation of the structure indicators of grain sorghum yield capacity in the conditions of the Right bank Forest steppe zone of Ukraine. The experiment was carried out in the zone of unstable humidity in 2016–2020. The trial scheme consisted in studying grain sorghum cultivars and various fertilizer rates; the trial was initiated with the method of regular replications, a fourfold replication was applied. Having analyzed the research results, it was found out that as the fertilizer rates increased, the element indicators of the yield structure also increased; in turn grain yield capacity of the studied cultivars was higher. However, the optimal fertilizer rate for the expected yield is the estimated one which will reduce the production cost of the output.

Inter-annual changes of zooplankton in the kultuk zone of the Volga River delta in the spring period

The studies conducted in spring have shown the main trends in changes in the structure of zooplankton in the kultuk zone of the Volga River delta in years that differ in hydrological and temperature regimes. It was revealed that in low-water years (2012, 2014), with a decrease in the volume of runoff, water level, and a reduction in the duration of floods, zooplankton was characterized by relatively low species richness, high biomass of Copepoda and Cladocera. At the same time, the highest rates of specific species richness, biomass and abundance of all zooplankton groups were observed at spring of a low-water year (2014), which was characterized by a runoff volume during the flood of 101 km3, a high pre-flood water levels, the absence of a sharp and significant dilution, as well as an early warm spring and gradual warming of the waters. In the year (2012), characterized by a volume of runoff during the flood period of 114 km3, a decrease in water level and a sharp increase in temperature before the flood, and then its rapid rise with dilution by cold waters, zooplankton was distinguished by the minimum species richness, a low number of ecological groups and low abundance of Cladocera, but a high proportion of juvenile copepods (fine filter feeders) and in terms of biomass of active euryphagous predators and euryphagous collectors. In a medium-water year (2013) with a large volume of runoff during the flood of 140 km3, with early and high and long floods, zooplankton was distinguished by a high total number of species encountered, but a minimum abundance and biomass, which is associated with the “dilution effect” and an increase in the areas of flooded rich in higher aquatic vegetation.

Changes in bivalve assemblages at the onset of the OAE2 event in the Peri-Tethyan area (Bohemian Cretaceous Basin)

The Ocean Anoxic Event (OAE2) at the Cenomanian-Turonian boundary presents a unique record of gradual global warming and its effects on benthic organisms. The present research considers a palaeoecological, systematical and statistical evaluation of bivalve assemblages from the Pecínov Member in the Bohemian Cretaceous Basin. The well-exposed succession of Cenomanian through lower Turonian strata contains one of the most complex records of the OAE2 in central Europe. In total, 392 specimens have been studied and assigned to 24 genera within 21 families and 9 orders. The bivalve association prior to the positive shift of the δ13Corg (peak “a” sensu global carbon curve; lower part of the Metoicoceras geslinianum Zone) is strongly dominated by infaunal suspension feeders, followed by semi-infaunal suspension feeders. The near-absence of free-living epifaunal bivalves may be linked to a very fine, muddy substrate and water turbidity, a limiting factor for many epifaunal species. Infaunal deposit feeders are also present but comparatively rare, indicating a nutrient-rich environment with energy levels sufficiently high to keep organic matter in suspension. The Cucullaea glabra – Pseudoptera anomala assemblage of this level is considered to have formed during normal, shallow (15–20 m, supported by abundant material of Pinna) marine conditions. The association inhabiting the area above this level (upper part of the M. geslinianum Zone, S. gracile/E. septemseriatum Subzone) is characterized by the Panopea gurgitis – Rhynchostreon suborbiculatum assemblage suggesting considerably shallower depths and higher energy. Clusters of Modiolus and small oysters characterize the upper parts directly prior to the prominent positive δ13Corg peak “b” (the major peak of OAE2 CIE; ? base/lower part of the N. juddii Zone). No benthic fauna occurs above this level.