Hasil untuk "General. Including nature conservation, geographical distribution"

Theint Thandar Bol, Min Hein Htike, Todd K. Fuller et al.

Kamal El fallah, Hicham Ouhakki, Khadija El kharrim et al.

Kai‐Philipp Gladow, Marla Jablonski, Nayden Chakarov et al.

The loss of top predators has been shown to lead to drastic changes in community structure. An important part of this is the shift in behaviour of other species. The understanding of such changes is scarce because recordings of behavioural reactions towards lost species are rarely done. This is important for predators experiencing predation pressure themselves, known as intraguild predation. Re‐colonizations offer the unique possibility to fill this knowledge gap. However, only a few studies tested experimentally how subordinate predators change their behaviour towards differently sized top predators. Birds adjust the level of nest defence in response to perceived threats. Therefore, we expected birds of prey in intraguild predation systems to show an appropriate level of nest defence against the predator they are faced with, with the highest level shown against the largest predator. We tested this by placing models of eagle owls Bubo bubo and goshawks Accipiter gentilis close to nests of common buzzards Buteo buteo and measured the reaction. Overall, aggression by common buzzards towards eagle owls was greater than towards goshawks, but effect sizes were small and had relatively large confidence intervals. We therefore conclude that the largest predator and the second‐largest predator provoke similarly high nest defences. This shows that in ecological communities the largest predator and smaller predators may not belong to different categories from the viewpoint of intraguild prey. Different top predators might be perceived as comparable threats.

Akhil Uniyal, Indu K. Dihingia, Yosuke Mizuno et al.

The horizon-scale images of supermassive black holes (BHs) by the Event Horizon Telescope Collaboration (EHT) have provided new opportunities to test general relativity and other theories of gravity. In view of future projects, such as the next-generation Event Horizon Telescope (ngEHT) and the Black-Hole Explorer (BHEX), having the potential of enhancing our ability to probe extreme gravity, it is natural to ask: \textit{how much can two black-hole images differ?} To address this question and assess the ability of these projects to test theories of gravity with black-hole shadows, we use general-relativistic magnetohydrodynamic and radiative-transfer simulations to investigate the images of a wide class of accreting BHs deviating from the Kerr solution. By measuring the mismatch between images of different BHs we show that future missions will be able to distinguish a large class of BHs solutions from the Kerr solution when the mismatch in the images exceeds values between $2\%$ and $5\%$ depending on the image-comparison metric considered. These results indicate future horizon-scale imaging with percent-level image fidelity can place meaningful observational constraints on deviations from the Kerr metric and thereby test strong-field predictions of general relativity.

Mezgebu Ashagrie, Kemal Jilo, Shimelis Aynalem Zelelew

Juarez C.B. Pezzuti, Jansen Zuanon, Priscila F.M. Lopes et al.

Lula’s presidency in Brazil offers great hope for the environment but plans for hydroelectric dams in Amazonia represent an area of concern. The Belo Monte hydroelectric power plant that Lula promoted in his previous administrations and still defends illustrates the contradictions. In 2015 Belo Monte diverted water from the Xingu River through a canal that, since 2019, has left a 130-km river stretch with less than 30% of its natural annual discharge. This has compromised the food security of three Indigenous groups and of traditional non-indigenous river-dwelling people dependent on the river’s fish and turtles. Endemic (and threatened) species and unique ecosystems are now being eliminated. The pending renewal of Belo Monte’s operating license poses a test for the Lula administration’s socioenvironmental commitment. We offer suggestions for improved governance for existing dams like Belo Monte but conclude that no more large dams should be built in Amazonia.

Frontiers Production Office

Yichen Fu, Xiaoyan Chen, Yuchen Liu et al.

Remote seawater has been considered a potential refuge for corals in the face of anthropogenic disturbances. However, these remote areas may receive increased atmospheric N deposition, and the ecological consequences remain unclear. This field survey revealed coral-algal phase shifts in the mid-north of the South China Sea. These shifts were observed in 44%, 13.6%, and 26.5% of the sampled reef sites at depths of 1-4 m, 5-8 m, and 10-15 m, respectively. Over 50% of sections in the deeper depths hosted fewer corals compared to shallower areas, coinciding with a higher abundance of macroalgae in the deeper layers. Furthermore, based on long-term observation of atmospheric N flux, laboratory experiments were conducted to explore the cause of coral declines. The results indicate that N supply efficiently promoted macroalgae growth. The saturation of N absorption by macroalgae occurred within 2 weeks, leading to nutrient accumulation in seawater, especially nitrate, which had a direct impact on corals. While moderate N fluxes appeared to mitigate coral bleaching, high N fluxes, even with a balanced P supply or medium level of nutrients with an imbalanced N/P ratio, can both increase the susceptibility of corals to heat bleaching. This study explains the coral-algal phase shift in remote and relatively deep seawater and improves understanding of the cause-and-effect relationship between atmospheric N deposition and coral reef decline.

José Carlos Báez, José Carlos Báez

Rehana Naz, Willy Hereman

The Lie-point symmetry method is used to find some closed-form solutions for a constitutive equation modeling stress in elastic materials. The partial differential equation (PDE), which involves a power law with arbitrary exponent n, was investigated by Mason and his collaborators (Magan et al., Wave Motion, 77, 156-185, 2018). The Lie algebra for the model is five-dimensional for the shearing exponent n > 0, and it includes translations in time, space, and displacement, as well as time-dependent changes in displacement and a scaling symmetry. Applying Lie's symmetry method, we compute the optimal system of one-dimensional subalgebras. Using the subalgebras, several reductions and closed-form solutions for the model are obtained both for general exponent n and special case n = 1. Furthermore, it is shown that for general n > 0 the model has interesting conservation laws which are computed with symbolic software using the scaling symmetry of the given PDE.

Jesús E. Sáenz-Ceja, Manuel E. Mendoza

Carlos Alberto Saenz Cortez, Johanna Mariel Vilela Saldarriaga

Mediante monitoreos ornitológicos realizados en las ex relaveras de Azalia y Chonta del 9 al 12 de marzo de 2021, ubicadas en el Distrito de Goyllarisquizga (Pasco), se ha determinado que la calidad ambiental es de ponderación Media. Señalándose, además, que es importante la restauración y reforestación de los componentes ecológicos de ellas ya que, según los resultados obtenidos, el 89.06% de las especies encontradas se encuentran registradas en la Lista roja de especies amenazadas de la UICN, catalogadas como Leves según la versión 3.1 de la segunda edición de las Categorías y criterios de la Lista roja de la UICN. Asimismo, el 10.92% de aves son endémicas de la zona, que significaría que solo pueden habitar ese tipo de ecosistemas, y el 3.36% de aves son catalogadas como CITES y se ubican en el Apéndice II de CITES, por lo que se puede concluir que el 89.06% de las especies son sensibles.

Alex N. Tidd, Alex N. Tidd, Vasquez Caballero et al.

There is an urgent need to assess the extent to which the global fishing enterprise can be sustainable in the face of climate change. Artisanal fishing plays a crucial role in sustaining livelihoods and meeting food security demands in coastal countries. Yet, the ability of the artisanal sector to do so not only depends on the economic efficiency of the fleets, but also on the changing productivity and distribution of target species under rapid climate change in the oceans. These impacts are already leading to sudden declines, long-term collapses in production, or increases in the price of fish products, which can further exacerbate excess levels of fishing capacity. We examined historical changes (1950-2014) in technical efficiency within the global artisanal fishing fleets in relation to sea surface temperature anomalies, market prices by taxonomic group, and fuel costs. We show that temperature anomalies affected countries differently; while some have enhanced production from an increase in the resource distribution, which alter the structure of the ecosystem, others have had to adapt to the negative impacts of seawater warming. In addition, efficiency decreases are also related to rises in global marine fish price, whereby more labour and capital are attracted into the fishery, which in turn can lead to an excess in fleet capacity. Our results contribute to the understanding of how the effects of climate-induced change in the oceans could potentially affect the efficiency of artisanal fishing fleets.

Lingjing Xu, Lingjing Xu, Lingjing Xu et al.

The Kuroshio Current flows northeastward along the East China Sea (ECS) shelf break, carrying a large amount of nutrients, and is thus an important source of nutrients for the ECS. The mainstream and transport of the Kuroshio Current are significantly affected by mesoscale eddies. However, the influence of mesoscale eddies on the Kuroshio nutrient input into the ECS is unknown. We add constructed cyclonic and anticyclonic eddies to a hydrodynamic model to explore the influence of mesoscale eddies on cross-shelf Kuroshio phosphate input into the ECS. This model suitably reproduces the fate of mesoscale eddies and the variation in the Kuroshio Current during eddy-current interactions. The simulation results reveal that during the strong interaction between the Kuroshio Current and mesoscale eddy east of Taiwan, the cyclonic eddy reduces the on-shelf phosphate flux, while the anticyclonic eddy increases the Kuroshio phosphate input to the ECS. When the anticyclonic eddy moves to the Okinawa Trough, it reduces the Kuroshio phosphate input into the ECS.These basic features are not sensitive to the initial latitude of the eddy center east of Taiwan. The change in cross-shelf phosphate flux is caused by the changes in cross-shelf velocity and phosphate concentration along the shelf. Momentum balance analyses suggest that the change in cross-shelf velocity is mainly caused by the change in the pressure gradient term due to eddy-induced changes in sea surface height in the horizontal direction and isotherm tilting in the vertical direction. The advection-diffusion equation analysis shows that the change in phosphate concentration along the shelf is attributed to changes in the upper horizontal advection and lower vertical advection of phosphate, which are induced by the upper phosphate change and vertical velocity change along the shelf, respectively. This study has important implications for the possible response of the ECS ecosystem to mesoscale eddies that are partly triggered by enhanced typhoons east of Taiwan under global warming.

William J. Wolf, James Read, Quentin Vigneron

The geometric trinity of gravity comprises three distinct formulations of general relativity: (i) the standard formulation describing gravity in terms of spacetime curvature, (ii) the teleparallel equivalent of general relativity describing gravity in terms of spacetime torsion, and (iii) the symmetric teleparallel equivalent of general relativity (STEGR) describing gravity in terms of spacetime non-metricity. In this article, we complete a geometric trinity of non-relativistic gravity, by (a) taking the non-relativistic limit of STEGR to determine its non-relativistic analogue, and (b) demonstrating that this non-metric theory is equivalent to the Newton--Cartan theory and its teleparallel equivalent, i.e., the curvature and the torsion based non-relativistic theories that are both geometrised versions of classical Newtonian gravity.

Bin Zhou, Petter Holme, Zaiwu Gong et al.

Although the origin of the fat-tail characteristic of the degree distribution in complex networks has been extensively researched, the underlying cause of the degree distribution characteristic across the complete range of degrees remains obscure. Here, we propose an evolution model that incorporates only two factors: the node's weight, reflecting its innate attractiveness (nature), and the node's degree, reflecting the external influences (nurture). The proposed model provides a good fit for degree distributions and degree ratio distributions of numerous real-world networks and reproduces their evolution processes. Our results indicate that the nurture factor plays a dominant role in the evolution of social networks. In contrast, the nature factor plays a dominant role in the evolution of non-social networks, suggesting that whether nodes are people determines the dominant factor influencing the evolution of real-world networks.

Wanjie Cai, Wanjie Cai, Haokun Liu et al.

This study was conducted to investigate the effects of substitution of dietary fishmeal (FM) by compound plant protein supplemented with essential amino acids on growth performance, plasma physiology, and muscle growth-related genes of gibel carp (Carassius auratus gibelio). Four diets with equal digestible protein were prepared, where 30FM (control feed) contained 30% FM and land animal protein as a protein source, 10FM contained 10% FM, PMAa contained full plant meal (PM) supplemented with crystalline amino acid, and PM contained full PM feed. There was no significant difference in the specific growth rate (SGR) with 30FM, 10FM, and PMAa diets (p > 0.05); however, the SGR of PM group was the lowest with significant difference (p < 0.05). Feed efficiency of the PM group was the lowest with significant difference (p < 0.05). The whole-body crude protein content of fish in PMAa group was significantly higher than that in each group with additional FM (p < 0.05). There were no significant differences in plasma total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) or low-density lipoprotein cholesterol (LDL-C), and free amino acid profile of 30FM, 10FM, and PMAa groups (p > 0.05); however, they were significantly higher than that in PM group (p < 0.05). The expression of key genes in the TOR signaling pathway (tor, s6k1, 4e-bp2, and eif4e), autophagy (ulk1 and atg13), and ubiquitin–proteasome (trim63 and znrf2) system of the PMAa group was similar to that of the FM group (p > 0.05), indicating that the muscle growth-related biomarker genes were positively regulated by the appropriate dietary amino acid composition at the transcriptional level. These results suggest that FM in gibel carp diet can be totally replaced by PM without negative impact on growth performance and muscle growth-related biomarkers at the transcriptional level, which provided the requirement of digestible protein and balanced amino acid profile is satisfied.

Fabian Wolf, Katja Seebass, Christian Pansch et al.

During recent years, experimental ecology started to focus on regional to local environmental fluctuations in the context of global climate change. Among these, marine heatwaves can pose significant threats to marine organisms. Yet, experimental studies that include fluctuating thermal stress are rare, and if available often fail to base experimental treatments on available long-term environmental data. We evaluated 22-year high-resolution sea surface temperature data on the occurrence of heatwaves and cold-spells in a temperate coastal marine environment. The absence of a general warming trend in the data may in parts be responsible for a lack of changes in heatwave occurrences (frequency) and their traits (intensity, duration, and rate of change) over time. Yet, the retrieved traits for present-day heatwaves ensured most-natural treatment scenarios, enabling an experimental examination of the impacts of marine heatwaves and phases of recovery on an important temperate predator, the common sea star Asterias rubens. In a 68-days long experiment, we compared a 37- and a 28-days long heatwave with a treatment that consisted of three consecutive 12-days long heatwaves with 4 days of recovery in between. The heatwaves had an intensity of 4.6°C above climatological records, resulting in a maximum temperature of 23.25°C. We demonstrate that heatwaves decrease feeding and activity of A. rubens, with longer heatwaves having a more severe and lasting impact on overall feeding pressure (up to 99.7% decrease in feeding rate) and growth (up to 87% reduction in growth rate). Furthermore, heatwaves of similar overall mean temperature, but interrupted, had a minor impact compared to continuous heatwaves, and the impact diminished with repeated heatwave events. We experimentally demonstrated that mild heatwaves of today’s strength decrease the performance of A. rubens. However, this echinoderm may use naturally occurring short interruptions of thermal stress as recovery to persist in a changing and variable ocean. Thus, our results emphasize the significance of thermal fluctuations and especially, the succession and timing of heat-stress events.

Yu Pan, Zhicheng Sun, Tianxiang Gao et al.

Acanthogobius ommaturus is a large, fast-growing annual fish widely distributed in coastal and estuarine areas. The adults will die after breeding, and its life cycle is only 1 year. The first chromosome-level genome assembly of A. ommaturus was obtained by PacBio and Hi-C sequencing in this study. The final genome assembly after Hi-C correction was 921.49 Mb, with contig N50 and scaffold N50 values of 15.70 Mb and 40.99 Mb, respectively. The assembled sequences were anchored to 22 chromosomes by using Hi-C data. A total of 18,752 protein-coding genes were predicted, 97.90% of which were successfully annotated. Benchmarking Universal Single-Copy Orthologs (BUSCO) assessment results for genome and gene annotations were 93.6% and 84.6%, respectively. A. ommaturus is phylogenetically closely related to Periophthalmodon magnuspinnatus and Boleophthalmus pectinirostris, diverging approximately 31.9 MYA with the two goby species. The A. ommaturus genome displayed 597 expanded and 3,094 contracted gene families compared with the common ancestor. A total of 1,155 positive selected genes (PSGs) (p < 0.05) were identified. Based on comparative genomic analyses, we obtained several expanded genes such as acsbg2, lrp1, lrp6, and znf638 involved in lipid metabolism. A total of twenty candidate genes were identified under positive selection, which associated with lifespan including ercc6, igf1, polg, and tert. Interspecific collinearity analysis showed a high genomic synteny between A. ommaturus and P. magnuspinnatus. The effective population size of A. ommaturus decreased drastically during 200–100 Ka because of Guxiang ice age and then increased gradually following warm periods. This study provides pivotal genetic resources for in-depth biological and evolutionary studies, and underlies the molecular basis for lipid metabolism.

Feifei Zhang, Feifei Zhang, Feifei Zhang et al.

The effects of the spectrum on the development, respiratory metabolism, and antioxidant capacity of the larval swimming crab Portunus trituberculatus were studied. Seven light spectra, i.e., purple (400 nm), blue (425 nm), cyan (510 nm), green (525 nm), yellow (598 nm), red (638 nm), and white (full spectrum), were estimated. The larvae had the optimum survival rate and development under cyan light. On the contrary, larvae in red and yellow lights had poor growth performance. The oxygen consumption rate (OCR) dropped while the ammonia excretion rate (AER) rose as the larvae developed. Early larvae’s oxygen-nitrogen ratio (O: N) fell when exposed to red light, suggesting more protein was utilized in the respiratory process. Regarding the antioxidant system, crab had the lowest malondialdehyde (MDA) under green, cyan and yellow light, and the highest total antioxidant capacity (T-AOC) in cyan light. Taken together, the current results suggest that cyan was the optimum spectrum for the development of P. trituberculatus larvae.