Spring Conditions Research Articles

Effects of temperature on metabolic rate during metamorphosis in the alfalfa leafcutting bee.

Spring conditions, especially in temperate regions, may fluctuate abruptly and drastically. Environmental variability can expose organisms to temperatures outside of their optimal thermal ranges. For ectotherms, sudden changes in temperature may cause short- and long-term physiological effects, including changes in respiration, morphology, and reproduction. Exposure to variable temperatures during active development, which is likely to occur for insects developing in spring, can cause detrimental effects. Using the alfalfa leafcutting bee, Megachile rotundata, we aimed to determine if oxygen consumption could be measured using a new system and to test the hypothesis that female and male M. rotundata have a thermal performance curve with a wide optimal range. Oxygen consumption of M. rotundata pupae was measured across a large range of temperatures (6-48°C) using an optical oxygen sensor in a closed respirometry system. Absolute and mass-specific metabolic rates were calculated and compared between bees that were extracted from their brood cells and those remaining in the brood cell to determine whether pupae could be accurately measured inside their brood cells. The metabolic response to temperature was non-linear, which is an assumption of a thermal performance curve; however, the predicted negative slope at higher temperatures was not observed. Despite sexual dimorphism in body mass, sex differences only occurred in mass-specific metabolic rates. Higher metabolic rates in males may be attributed to faster development times, which could explain why there were no differences in absolute metabolic rate measurements. Understanding the physiological and ecological effects of thermal environmental variability on M. rotundata will help to better predict their response to climate change.

Variability and properties of liquid-dominated clouds over the ice-free and sea-ice-covered Arctic Ocean

Abstract. Due to their potential to either warm or cool the surface, liquid-phase clouds and their interaction with the ice-free and sea-ice-covered ocean largely determine the energy budget and surface temperature in the Arctic. Here, we use airborne measurements of solar spectral cloud reflectivity obtained during the Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD) campaign in summer 2017 and the Arctic Amplification: FLUXes in the Cloudy Atmospheric Boundary Layer (AFLUX) campaign in spring 2019 in the vicinity of Svalbard to retrieve microphysical properties of liquid-phase clouds. The retrieval was tailored to provide consistent results over sea-ice and open-ocean surfaces. Clouds including ice crystals that significantly bias the retrieval results were filtered from the analysis. A comparison with in situ measurements shows good agreement with the retrieved effective radii and an overestimation of the liquid water path and reduced agreement for boundary-layer clouds with varying fractions of ice water content. Considering these limitations, retrieved microphysical properties of clouds observed over the ice-free ocean and sea ice in spring and early summer in the Arctic are compared. In early summer, the liquid-phase clouds have a larger median effective radius (9.5 µm), optical thickness (11.8) and effective liquid water path (72.3 g m−2) compared to spring conditions (8.7 µm, 8.3 and 51.8 g m−2, respectively). The results show larger cloud droplets over the ice-free Arctic Ocean compared to sea ice in spring and early summer caused mainly by the temperature differences in the surfaces and related convection processes. Due to their larger droplet sizes, the liquid clouds over the ice-free ocean have slightly reduced optical thicknesses and lower liquid water contents compared to the sea-ice surface conditions. The comprehensive dataset on microphysical properties of Arctic liquid-phase clouds is publicly available and could, e.g., help to constrain models or be used to investigate effects of liquid-phase clouds on the radiation budget.

Tree-ring isotopic imprints on time series of reproductive effort indicate warming-induced co-limitation by sink and source processes in stone pine.

Increasing evidence indicates that tree growth processes, including reproduction, can be either sink- or source-limited, or simultaneously co-limited by sink and source, depending on the interplay between internal and environmental factors. We tested the hypothesis that the relative strengths of photosynthate supply and demand by stem growth and reproduction create variable competition for substrate that is imprinted in the tree-ring isotopes (C and O) of stone pine (Pinus pinea L.), a masting gymnosperm with large costs of reproduction, under warming-induced drought. Across five representative stands of the Spanish Northern Plateau, we also identified reproductive phases where weather drivers of cone yield (CY) have varied over a 60-year period (1960-2016). We found that these drivers gradually shifted from winter-spring conditions 3 years before seed rain (cone setting) to a combination of 3- and 1-year lagged effects (kernel filling). Additionally, we observed positive regional associations between carbon isotope discrimination (Δ13C) of the year of kernel filling and CY arising at the turn of this century, which progressively offset similarly positive relationships between Δ13C of the year of cone setting and CY found during the first half of the study period. Altogether, these results pinpoint the increasing dependence of reproduction on fresh assimilates and suggest sink and source co-limitation superseding the sink-limited functioning of reproduction dominant before 2000. Under climate warming, it could be expected that drier conditions reinforce the role of source limitation on reproduction and, hence, on regeneration, forest structure and economic profit of the nutlike seeds of the species.

Influence of sediments burying the discharge area of a karst aquifer on the groundwater flow field—Numerical testing of conceptual models

AbstractKarst springs are a natural result of karst water discharging to the surface through unimpeded pathways where the water table meets the surface. This study investigates the impact of alluvial deposits of varying thicknesses and permeabilities burying the main outlet (karst spring) of a well‐developed conduit network on karst drainage, including the development of hydraulic heads, drainage patterns and conduit‐matrix interactions in response to a positive base‐level shift. Numerical testing using FEFLOW on a simplified conceptual model of a hypothetical karst aquifer with six different model configurations was used to examine various drainage structures (with and without flow through a conduit), spring conditions (free vs. partially/fully clogged), sediment cover thickness (20 and 50 m), and hydraulic conductivity of the sediments (low and high). The numerical testing model incorporated one‐dimensional discrete feature elements to simulate conduit flow and coupled conduit‐matrix interactions. Results indicate that even with a fully plugged outlet, the conduit network remains a significant contributor to the drainage system, collecting water from the matrix in the recharge zone. As the outlet becomes buried, the hydraulic head increases along the conduit, forcing water back up into the matrix. The elevated hydraulic head in the karst system will cause new conduits to form at the contact between limestone and sediments, creating new potential spring sites (or reactivating existing paleo‐phreatic levels). Artesian conditions will occur below the low permeability sediments. These findings provide valuable insights into the responses of natural karst systems.

The timing of reproduction is responding plastically, not genetically, to climate change in yellow-bellied marmots (Marmota flaviventer).

With global climates changing rapidly, animals must adapt to new environmental conditions with altered weather and phenology. The key to adapting to these new conditions is adjusting the timing of reproduction to maximize fitness. Using a long-term dataset on a wild population of yellow-bellied marmots (Marmota flaviventer) at the Rocky Mountain Biological Laboratory (RMBL), we investigated how the timing of reproduction changed with changing spring conditions over the past 50 years. Marmots are hibernators with a 4-month active season. It is thus crucial to reproduce early enough in the season to have time to prepare for hibernation, but not too early, as snow cover prevents access to food. Importantly, climate change in this area has, on average, increased spring temperatures by 5°C and decreased spring snowpack by 50 cm over the past 50 years. We evaluated how female marmots adjust the timing of their reproduction in response to changing conditions and estimated the importance of both microevolution and plasticity in the variation in this timing. We showed that, within a year, the timing of reproduction is not as tightly linked to the date a female emerges from hibernation as previously thought. We reported a positive effect of spring snowpack but not of spring temperature on the timing of reproduction. We found inter-individual variation in the timing of reproduction, including low heritability, but not in its response to changing spring conditions. There was directional selection for earlier reproduction since it increased the number and proportion of pups surviving their first winter. Taken together, the timing of marmot reproduction might evolve via natural selection; however, plastic changes will also be extremely important. Further, future studies on marmots should not operate under the assumption that females reproduce immediately following their emergence.

Environmentally driven changes in Atlantic salmon oxidative status interact with physiological performance

Farmed Atlantic salmon in sea cages experience natural seasonal changes in seawater temperature and photoperiod. Atlantic salmon have more oxidized tissues in spring and early summer, and this corresponds to the period of increasing day length, temperature, and growth rate. However, the molecular mechanisms underlying the redox metabolism of Atlantic salmon exposed to the interaction of seasonal cues remain unclear. This study aims to investigate the effect of seasonal changes in temperature and photoperiod on the redox metabolism at the molecular level of Atlantic salmon. Salmon reared in tanks were subjected to simulated natural (for farmed salmon in sea cages) photoperiod and temperature to mimic spring and summer (March to August). We found that the changing photoperiod and temperature, which were simulated to spring and summer conditions, influenced the redox metabolism of Atlantic salmon over the experimental period. We showed that increased utilization of tissue antioxidants such as vitamin C, vitamin E, and reduced glutathione in the spring was restored in August. The more reduced glutathione-based redox potentials and the low levels of malondialdehyde (MDA) in August in liver and muscle suggest lowered tissue oxidative activity at that time. We further revealed that the expression profiles of genes involved in growth hormone signaling and cell cycle regulation were correlated with oxidative stress patterns. Together, these promising results reveal the molecular mechanisms underlying the ecological implications of oxidative status. The study provides new insight into the possible role redox signaling plays in the growth regulation of fish to the seasonal shift in environmental factors.

Seasonal heat stress compromises testicular thermoregulation and semen quality of Dorper rams raised in a desert climate

Dorper rams are widely distributed throughout the world under different climatic conditions, however, little is known about their reproductive performance in desert regions. Ten Dorper rams were individually housed and exposed to thermoneutrality for 35 d in spring (23.6 ± 5.6 °C, mean ± SD) and outdoor heat stress (HS) for 35 d in summer (33.6 ± 2.0 °C) to evaluate the effect of seasonal HS on physiological responses, testicular biometry, and seminal quality under desert climatic conditions. Rectal temperature, respiration rate and coat surface temperatures in different body regions were measured every 7 d (0600, 1200, and 1800 h); also, testicular biometry was registered at 0600 h. Semen was collected via an artificial vagina 3 d after physiological variables were measured and seminal traits were evaluated. Rectal temperature, respiration rate and coat surface temperatures were higher (P < 0.01) at each hour of measurement in summer compared to spring. Overall, scrotal length and circumference, as well as testicular volume were higher (P < 0.01) in summer than in spring. Compared to spring conditions, summer HS caused lower (P ≤ 0.05) sperm concentration and viability combined with a higher percentage of sperm abnormalities without affecting ejaculate volume. Both mass and sperm motility were similar between seasons in the first two sampling weeks, and then decreased (P ≤ 0.03) due to summer HS. In conclusion, Dorper rams developed testicle hyperthermia and, consequently, showed poor semen quality due to the high environmental temperatures prevailing in desert regions.

GEOCHEMICAL CONDITIONS OF SULLAR SPRING: FORMATION OF AUTHIGENIC MINERALS AND METHANE FLUXES

Link for citation: Soldatova E.A., Sidkina E.S., Kiriukhin B.A., Maximov P.N., Krivenok L.A., Ivanov V., Tananaev N.I. Geochemical conditions of Sullar spring: formation of authigenic minerals and methane fluxes. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 16-33. In Rus. Relevance and the research object. Interpermafrost aquifers and areas of their discharge with seasonal ice covers are special permafrost-hydrogeological and hydrochemical systems that are not typical for the thick continuous permafrost zone of Central Yakutia. Differences in chlorofluorocarbon content indicate the anaerobic conditions of some springs suggesting microbial degradation of these compounds by methanogenic bacteria. In the discharge area of such springs, a sharp change in the geochemical conditions takes place leading to a transformation in the water chemical composition and boosting the processes of authigenic mineral formation in this buffer area. In current work we considered the geochemical system of the Sullar spring – the most northern and the least studied among interpermafrost groundwater discharge zones of the Lena River right bank. Intensive accumulation of authigenic minerals was found in the Sullar discharge area during field research. It was Fe compounds with bacterial mats as an opalescent film. Some researchers state the connection between the transformation of Fe compounds during permafrost melting and the migration and transformation of organic matter, including its consumption by microorganisms with further methane emission. We assumed that there is a relationship between the authigenic mineral formation and the content and emission of methane in the discharge area of the spring. This research is the first comprehensive description of the hydrochemistry of the interpermafrost water of the Sullar spring. The aim of the research was to explore influence of geochemical conditions and microbial communities on formation of authigenic minerals and methane fluxes, in particular the effect of the change of geochemical conditions due to groundwater discharge on Fe precipitation and to analyze the relation of that process with methane fluxes. For this purpose, we study water chemical composition of the Sullar spring, measure methane fluxes from water surface and analyze mineral and microbial composition of secondary mineral crusts and bottom eluvium collected near water sampling points. Methods. The main element content was determined by ion chromatography. The concentrations of the bicarbonate ion and dissolved carbon dioxide were calculated by the equilibrium modeling method based on the pH and Eh values of the system. The content of trace elements was measured by mass spectrometry with inductively coupled plasma. To identify seasonal and annual variability, a retrospective analysis of the water chemical composition of the Sullar spring for the period from 1962 to 2020 was carried out. Methane fluxes were measured using the chamber method. The methane concentration was determined by gas chromatography with a flame ionization detector. The features of the secondary mineral crusts and bottom eluvium were determined using a petrographic microscope. The chemical composition of individual mineral phases was evaluated using a scanning electron microscope equipped with a detector for energy dispersive X-ray spectral microanalysis. The DNA concentration was measured on a fluorimeter. Amplicon libraries were generated by polymer chain reaction with universal primers for the V4 region. Equilibrium modeling was carried out using the HCh software.

Character Association Study in Maize Hybrids Developed through Integration of Rapid Cycle Genomic Selection and Doubled Haploid Technology for Heat Stress Tolerance

Heat stress is becoming a major constraint for maize production; therefore heat stress resilience has emerged as an important aspect in maize hybrids targeted for post rainy spring season. Selection of genotypes based on high grain yield under heat stress condition is often misleading and the identification of secondary traits also associated with grain yield may help in development of heat tolerant cultivars. Hence, the present research work to study the association of traits was conducted during summer and kharif 2018 and rabi 2018-19 at Bheemarayanagudi and Raichur using 111 testcross progenies of doubled haploids derived from C1, C2 and C3 cycles of multi-parental synthetic population 1 and 2 improved through rapid cycle genomic selection for heat stress tolerance. The phenotypic correlation analysis under heat stress and optimal conditions, number of kernels per cob and cob girth exhibited the strong positive association with grain yield per plant. Further, under early spring condition number of kernels per cob, cob length, cob girth and 100 grain weight recorded the strong positive association with grain yield per plant. However, when considering across heat stress, early spring and optimal conditions, the grain yield per plant showed positive and significant strong to moderate association with the traits viz., number of kernels per cob, cob length and cob girth under all the seasons. In addition, days to 50% silking showed significant negative correlation with grain yield per plant under heat stress and optimal condition. Hence, the simultaneous selection criteria for the genotypes that exerts early silking, higher number of kernels per cob, higher cob girth and lengthy cob should be the priority of breeders to achieve higher grain yields in maize under heat stress condition as well as optimal conditions.

Seasonal patterns of carbon and water flux responses to precipitation and solar radiation variability in a subtropical evergreen forest, South China

Precipitation and energy are vital factors profoundly affecting carbon and water fluxes in subtropical forest ecosystems. However, knowledge of the seasonality of ecosystem productivity and water fluxes and their dominant controlling factors remains understudied. Based on 12 years (2003–2014) of eddy-covariance measurements, we examined how the seasonal carbon flux components and evapotranspiration respond to climatic variability in a subtropical forest ecosystem. Our results showed that both the magnitude and the percentage of gross ecosystem productivity (GEP) and ecosystem respiration (Reco) in winter increased. The enhanced GEP during winter and dampened Reco in summer and autumn were not sufficient to compensate for the decreased GEP in spring, summer and autumn, and simultaneously increased Reco in spring and winter. Thus, net ecosystem productivity (NEP) slightly diminished during the study period, and the majority of annual net carbon gains occurred in winter and spring with high water use efficiency. In addition, solar radiation predominantly contributed to GEP in spring and winter, while soil moisture is the main contributor in summer. ET greatly determined the GEP in autumn due to both were well-coupled. The vapor pressure deficit (VPD) was a major driver of Reco in summer and autumn inferred that Reco largely depends on substrate availability. However, Reco was mainly attributed to the soil environmental conditions (moisture and temperature) in spring and winter. Our results highlighted that the different extents and asynchronous responses of ecosystem carbon assimilation and respiration to altered energy and moisture availability determined the seasonal patterns of carbon and water fluxes, thus having important implications for assessing or projecting subtropical forest ecosystem responses to current climate change.

Bridging the gap between airborne and spaceborne imaging spectroscopy for mountain glacier surface property retrievals

Observations of glacier albedo are sparse, despite being a first-order control on net solar radiation and melt rates. Recent and forthcoming airborne and satellite imaging spectrometer missions increase our ability to record changes in albedo over time and space but will require an understanding of uncertainties, especially in areas of rugged terrain. Some of these uncertainties arise from the timing of acquisition and resolution of digital elevation models (DEM) that are used for topographic correction. We use the fine-resolution data (2 m) from the Airborne Coastal Observatory (ACO), an imaging spectroscopy and lidar remote sensing platform, to quantify the expected error from other airborne and satellite scale platforms. First, we describe our retrieval workflow - the Imaging Spectroscopy Snow and Ice Algorithm (ISSIA) that yields spatial retrievals of broadband albedo (BBA), optical grain size, and radiative forcing by light absorbing particles (RFLAP) using the coincident 2 m lidar DEM over mountain glaciers. We use two acquisitions over Place Glacier, British Columbia, Canada that represent typical spring and summer conditions as a baseline from which synthetic datasets were generated to represent data from coarser-scale imaging spectroscopy platforms. Each synthetic dataset was motivated by specific airborne and satellite platform scenarios and quantifies four sources of error: (1) DEM spatial resolution and elevation accuracy, (2) coincident vs non-coincident DEM collection, (3) imagery spatial resolution, and (4) spectral resolution. Use of a 30 m DEM introduced the most error in steep mountain terrain, which primarily increased error in the BBA and RFLAP retrievals. The timing of DEM acquisition mattered most for high-resolution imagery and in areas surrounding the glacier toe where mass loss occurred more rapidly. Coarse-resolution imagery did not fully capture spatial variability in surface properties and topography, which lowered variance and increased overall errors. Coarsening of spectral resolution from 5 nm to 10 nm had minimal impact on surface property retrieval and associated errors were independent of DEM or imagery resolution. A simple energy analysis showed that surface albedo error, due to topographic correction with coarse and non-coincident DEMs, resulted in melt rate errors ranging from 6 to 20% for airborne and 11–20% for satellite scenarios.

Modelling thermal sensitivity in the full phenological distribution: A new approach applied to the spring arboreal caterpillar peak

Abstract Advances in spring phenology are among the clearest biological responses to climate warming. There has been much interest in how climate impacts on phenology because the timings of key events have implications for species interactions, nutrient cycling and ecosystem services. To date most work has focused on only one aspect of population phenology, the effects of temperature on the average timing. In comparison, effects of temperature on the abundance of individuals and their seasonal spread are understudied, despite their potential to have profound impacts on species interactions. Here we develop a new method that directly estimates the effect of spring temperatures on the timing, height and width of the phenological distribution and apply it to temperate forest caterpillars, a guild that has been the focus of much research on phenology and trophic mismatch. We find that warmer spring conditions advance the timing of the phenological distribution of abundance by −4.96 days °C−1 and increase its height by 34% °C−1 but have no significant effect on the duration of the distribution. An increase in the maximum density of arboreal caterpillars with rising temperatures has implications for understanding climate impacts on forest food chains, both in terms of herbivory pressure and the resources available to secondary consumers. The new method we have developed allows the thermal sensitivity in the full phenological distribution to be modelled directly from raw data, providing a flexible approach that has broad applicability within global change research. Read the free Plain Language Summary for this article on the Journal blog.

Safe cycling in winter: Results of a case study on the role of de-icing in the city of Hamburg, Germany

Introduction: In parts of Europe and North America, cycling volumes decrease in winter due to a reduction in subjective safety. To counter this, high-quality winter maintenance is required on cycle paths. At the moment, grit and sodium chloride are considered state-of-the-art gritting/de-icing materials in Germany. However, grit has to be removed after winter because it poses a serious injury risk on dry streets, and, in various German cities, using sodium chloride is prohibited on segregated bike paths due to the harmful impact on surrounding trees. Therefore, there is a need for alternative gritting/de-icing materials. Method: We used a mixed-methods approach consisting of qualitative and quantitative surveys together with laboratory investigations and a life cycle assessment to find suitable alternatives to sodium chloride and grit for use on segregated bike paths, and tested four de-icing materials (sodium chloride as a reference, sodium formate, calcium magnesium acetate or CMA, and potassium acetate) at two sites in Hamburg, Germany. The tests were accompanied by on-site cyclist surveys. Results: The results show that the use of alternative (non-sodium chloride) de-icing materials either reduces or eliminates negative impacts on the environment at a local level, for example on trees along the cycle path. However, this reduction goes hand in hand with increasing negative environmental impacts at a global level due to higher overall emissions associated with the tested alternative de-icing materials. Regarding cyclists’ safety, sodium formate was the only de-icing material which delivered comparable results to sodium chloride and should therefore be tested in extended conditions. Conclusions: Further research is needed on the large-scale application of the investigated de-icing agents on cycle paths in different cities, along with a survey of a larger number of cyclists. A final evaluation of the environmental aspects can only be made when the supply and production conditions for large-scale use are clear. Practical Applications: Basically there are two options for the practical application of de-icing materials: The usage of the costlier alternatives with better properties at a local level in the hope of fast development towards a better global GHG footprint in their manufacturing processes, or sticking to the use of grit and sodium chloride (where it is possible) while committing to improving clean-up after the snow and ice melt to prevent unsafe road conditions in spring.

Chemical composition and formation conditions of thermal spring “Teply Klyuch”, Primorskiy krai (Russia)

The paper presents the results of half-century geochemical parameters monitoring of thermal spring, called Teply Klyuch, occurring outside volcanic activity territory of the Russian Far East. The case of unique tectonic and geological conditions leading to formation of such deposits is being discussed as well. The waters of the deposit are characterized as warm, ultra-fresh, alkaline, and siliceous. It is controlled by the active part of the fault, which runs along the bed of the Amgu River and its watercourses, in the zone of intersection by a shallower fault. Formation of thermal waters probably took place in open fractures of deep faults, where atmospheric waters by downward flow penetrated to a depth of about 1.0–1.5 km and under the influence of heat of locally heated in the fault zone rocks acquired the temperature of +30 +40°C. The movement of heated water to the surface is caused by the thermolift. Discharge area goes along the opened cracks in the weakened zones located in the river valleys. In practical terms, the waters of the investigated deposit are applicable for therapeutic and prophylactic purposes, externally, in the form of baths for diseases of the musculoskeletal system, skin diseases, consequences of burns.

Dynamics of CO2, CH4, and N2O in Ria Formosa coastal lagoon (southwestern Iberia) and export to the Gulf of Cadiz

A first characterization of greenhouse gases had been carried out to study their role and impact in a productive transitional coastal system of the southern Portugal – Ria Formosa lagoon. To this purpose, the partial pressure of CO2 (pCO2) and the concentration of dissolved CH4 and N2O have been measured. Two surveys were carried out during 2020, at low tide under typical conditions of Spring (March) and end of Summer (October). The samplings sites were distributed along the costal lagoon covering: i) inner areas with strong human impact (influence of different flows of treated wastewater discharges); and ii) main channels in connection with the main inlets to study the exchanges with the ocean. In general, the highest values of the three greenhouse gases were found at the inner studied areas, especially affected by the disposal of treated effluents from wastewater treatment plans, in October. The mean water - atmosphere fluxes of the CO2, CH4 and N2O are positive, showing that the study area acts as a source of these gases to the atmosphere. On the other hand, it was calculated a rough estimation of the three gases globally exported from Ria Formosa to the ocean, through the main six inlets to evaluate the magnitude of the supply of these gases from Ria Formosa to the adjacent ocean. The mean CO2, CH4 and N2O horizontal water fluxes exported from all the inlets of Ria Formosa to the Gulf of Cadiz for both seasons, during low water, are 8.7 ± 3.9 mmol m−2 s−1, 8.0 ± 3.5 μmol m−2 s−1 and 3.2 ± 1.5 μmol m−2 s−1, which corresponds to a mass transport through the inlets section of 0.7 ± 0.7 kg s−1, 0.2 ± 0.2 g s−1 and 0.2 ± 0.3 g s−1 respectively. From these estimates, as expected, the higher mass transport was found at the larger and deeper inlets (Faro-Olhão and Armona).

HYDRODYNAMIC AND BOUSSINESQ WAVE MODELING FOR THE N219 AMPHIBIOUS AIRCRAFT SEAPLANE DOCK DEVELOPMENT PLAN IN PANJANG ISLAND

The flight test of N219 Amphibious aircraft will be targeted in 2003/2024. For flight tests, these aircraft need a seaplane dock. One of the potential locations for the seaplane dock is Panjang Island at Seribu Islands. This study aims to know the characteristic of hydrodynamic and wave conditions and to determine whether Panjang Island is suitable for the seaplane dock. This study uses a modeling method with MIKE 21 FM HD-SW module and MIKE 21 Boussinesq Wave (BW) module. The bathymetry data were obtained from the Indonesian Navy Hydrographic and Oceanographic Center (Pushidrosal), tide data is generated from Tide Model Driver (TMD), wave and wind data from ECMWF. The result of surface elevation validation between hydrodynamic modeling and TMD is 92%. During the west monsoon and spring conditions, the difference in the largest and lowest current velocity is quite large (0.018-0.199 m/s), on the other hand, when the tides are in neap conditions (0.008-0.144 m/s). Meanwhile, during the east monsoon and spring conditions, the difference in the largest and lowest current velocities is quite large (0.02-0.193 m/s), on the other hand, when the tides are in neap conditions (0.008-0.146 m/s). The maximum wave height resulting from the 50-year return period waveform modeling between 1.139 - 1.474 m. Meanwhile, the significant wave heights between 0.679 - 0.741 with a significant wave period of 13.45 seconds. In general, the current and wave conditions of the two locations are suitable for the construction of the seaplane dock, except that the dominant wave heights are still above the requirements.

Climate and land-use change drive population decline in a red-listed plant species

Land-use change is a perennial driver of biodiversity decline. However, climate change may pose novel pressures on species populations, adding to the mixture of anthropogenic threats. Determining the main causes for species decline is important for effective allocation of conservation efforts and for understanding the linkages between biodiversity decline and climate change. Here, we study the impacts of forest management, urbanization, and changes in spring climatic conditions on the presence of a threatened plant species, Pulsatilla patens. In addition, we examine if topographic heterogeneity has supported the persistence of species populations under climatic change starting from 1961. We modelled the effect of land-use and climate change both separately and jointly, finding that both drivers have individual and potentially direct impacts on the persistence of P. patens. This is in agreement with the historic standpoint of land-use change being the main threat for the species, as well as recent findings of the potentially harmful effects of altered climatic conditions in spring, e.g., through late frost damage following earlier emergence of flowers. However, we found no indication that topographic heterogeneity would offer a buffering effect, suggesting that changes in spring climatic conditions form a tangible threat to this species that is not alleviated in the current landscape. As climate change continues, it is likely that the number and intensity of stressors increases for a variety of species, which warrants further attention to the role of climate change and appropriate conservation action.

Discordant spatiotemporal dynamics of functional and phylogenetic diversity of rotiferan communities exposed to aquaculture effluent.

The growth of the human population brought about the global intensification of aquacultural production, and aquaculture became the fastest growing animal husbandry sector. Effluent from aquaculture is an anthropogenic environmental burden, containing organic matter, nutrients and suspended solids that affect water quality especially in the water bodies of high biodiversity and conservation value. Water quality assessment often relies on bioindicators, analysing changes in taxonomic diversity of various freshwater organismal groups. Stepping beyond taxon diversity, we used functional and phylogenetic diversities of rotifers to identify factors affecting their community organization in response to an aquaculture effluent gradient in the largest oxbow lake in the Carpathian Basin, Hungary. Sampling was carried out three times per season at five points along a 3.5 km section of the oxbow lake, including the point of effluent inflow. We used eight traits to evaluate functional diversity: body size, trophi type, feeding mode, protection type, body wall type, corona type, habitat preference and tolerance level. Functional and phylogenetic distances among the 24 species identified indicated trait conservatism. Rotiferan diversity increased with increasing distance from the point of influx in spring and summer. Among the factors affecting community organization in spring and summer, we find examples of environmental filtering, while in autumn the role of biotic interaction is more frequent. Under nutrient-rich conditions in spring and summer, organisms belonging to the same functional group were dominant, whereas under oligotrophic conditions, more diverse but less abundant groups were present. Considering functional and phylogenetic traits allowed us to identify organising forces of rotifer communities in the largest oxbow lake of the Hungarian Lowland.

Effects of variable ice–ocean surface properties and air mass transformation on the Arctic radiative energy budget

Abstract. Low-level airborne observations of the Arctic surface radiative energy budget are discussed. We focus on the terrestrial part of the budget, quantified by the thermal-infrared net irradiance (TNI). The data were collected in cloudy and cloud-free conditions over and in the vicinity of the marginal sea ice zone (MIZ) close to Svalbard during two aircraft campaigns conducted in the spring of 2019 and in the early summer of 2017. The measurements, complemented by ground-based observations available from the literature and radiative transfer simulations, are used to evaluate the influence of surface type (sea ice, open ocean, MIZ), seasonal characteristics, and synoptically driven meridional air mass transports into and out of the Arctic on the near-surface TNI. The analysis reveals a typical four-mode structure of the frequency distribution of the TNI as a function of surface albedo, the sea ice fraction, and surface brightness temperature. Two modes prevail over sea ice and another two over open ocean, each representing cloud-free and cloudy radiative states. Characteristic shifts and modifications of the TNI modes during the transition from winter to spring and early summer conditions are discussed. Furthermore, the influence of warm air intrusions (WAIs) and marine cold-air outbreaks (MCAOs) on the near-surface downward thermal-infrared irradiances and the TNI is highlighted for several case studies. It is concluded that during WAIs the surface warming depends on cloud properties and evolution. Lifted clouds embedded in warmer air masses over a colder sea ice surface, decoupled from the ground by a surface-based temperature inversion, have the potential to warm the surface more strongly than near-surface fog or thin low-level boundary layer clouds because of a higher cloud base temperature. For MCAOs it is found that the thermodynamic profile of the southward-moving air mass adapts only slowly to the warmer ocean surface.

Dry season physicochemical characteristics of a tropical meso-tidal estuary: cross river estuary, southeast nigeria

&#x0D; The Cross River estuary is a tide-dominated coastal plain estuary which empties into the Atlantic Ocean at the Bight of Biafra, Gulf of Guinea. It receives fresh water from major tributaries including Calabar, Great Kwa, Akpa-Yafe, Mbo and Little Kwa rivers; and plays a significant role in anthropogenic activities such as fishing exploitation and commerce. This research focuses on the assessment data from the hydrodynamic variability of the Cross River estuary. Data from April 2017 to March 2018 were generated from monitoring tidal current velocity in the estuary as well as the tidal variations under spring and neap tidal conditions. The result shows that the average current velocity in the water column was 0.85 m/s during flood tides and 0.96 m/s during ebb tides. Residual currents were observed to be seaward, with ebb dominance. In-situ measurements of physicochemical parameters including dissolved oxygen, temperature, pH, salinity, density and transparency were recorded at 55 geo-referenced sampling stations throughout the estuary in the dry season month of January, 2018. Further to this, salinity, temperature and pH varied from 0 – 20 ppt; 27.9-31.4°C; 5.4-8.4 respectively, and in increased seaward direction. The relationship between physicochemical parameters were interpreted using Pearson’s Correlation Matrix. Here, salinity showed significant correlations (p&lt;0.05) with pH while density showed significant correlations with temperature, salinity and pH (add reasons). This research study reveals that changes in tidal cycles and current velocity are important factors contributing to the observed variations in physicochemical properties of the Cross River estuary and thus, useful for effective monitoring of the estuary and similar meso-tidal systems.&#x0D;