Energy Acquisition Strategies Research Articles

Trophic niche and adaptation in highland lizards: sex has greater influences than species matching.

The plateau environments are typically arid, cool, and high altitude, posing formidable challenges to wildlife survival due to resource scarcity and harsh conditions. Unraveling ecological adaptability in severe conditions requires a deeper understanding of the niche characteristics of plateau species. Trophic niche, which is a comprehensive indicator describing the energy acquisition strategy of animals, remains relatively understudied in plateau species. Here, by combining stable isotopes and morphological data, we quantified the trophic niches of two allopatric lizard species (Phrynocephalus vlangalii and P. erythrurus) that live in the hinterland of the Qinghai-Tibetan Plateau,and explored how their trophic niches correlate with morphological and environmental factors. While both trophic niche and morphological traits were similar between species, noteworthy distinctions were observed between male and female Phrynocephalus lizards. The morphological traits associated with predation (i.e. limb length and head size) and reproduction (i.e. abdomen length), annual mean temperature, and sex played influential roles in shifting trophic niches. These results imply that sexual dimorphism may facilitate inter-sex divergence in resource utilization, leading to trophic niche variations in the highland lizards. Furthermore, extreme environmental stress can constrain interspecific divergence in morphological and trophic traits. Our findings illustrate the dynamic variations of trophic niches in highland lizards, contributing to a more comprehensive understanding of the adaptation strategies employed by lizard species in plateau environments.

Optimal trajectory planning of a small UAV using solar energy and wind energy

Due to size limitations and the working environment near the ground, small low-altitude unmanned aerial vehicles (UAVs) cannot carry large-area solar cells and energy storage devices. Solar energy alone has only a limited effect on the improvement of their endurance. To solve this problem, this study proposes the combination of solar energy technology and dynamic soaring technology to improve the endurance of small UAVs. Then, the optimal energy acquisition strategy based on the combination of solar energy and dynamic soaring technology is analyzed in terms of energy. The motion equations and energy acquisition and consumption models of a small solar UAV based on horizontal wind shear are established. Moreover, an optimal trajectory planning problem with the maximum charging power of rechargeable batteries as the optimization objective is proposed. The optimal trajectory is solved based on the hp adaptive pseudo-spectral method, and the optimal trajectory combining the two technologies is simulated and compared with the constant-altitude constant-velocity (CACV) trajectory of the UAV using only solar technology. The simulation results show that under the flight background of tmission = 6:00 (summer sunrise) and β = 0.125 s−1 (wind gradient of the wind shear), the optimized O-type trajectory decreased the energy consumption power by 39.86% and increased the solar energy acquisition power by 86.34% compared to the CACV trajectory. Consequently, the small UAV stores more energy in the rechargeable batteries to improve the endurance performance. Compared to the environment where the sun is located on the leeward side of the wind shear, the environment where the sun is located on the windward side of the wind shear can enable the UAV to acquire more energy through the optimized O-type trajectory.

Energy acquisition strategy for reproduction in a semelparous squid

BackgroundEnergy demand for reproduction leads to a wide diversity of foraging and life-history strategy among wild animals, linking to a common objective to maximize reproductive success. Semelparous squid species in particular can use up to 50% of the total energy intake for reproduction. However, the energy acquisition strategy for reproduction is still a controversial issue regarding whether the squid shift in diet ontogenetically. Here we used Argentinean shortfin squid (Illex argentinus) as a case study to investigate the strategy of energy acquisition for reproduction, by analyzing energy density of the squid’s reproductive tissues including ovary, nidamental glands and oviduct eggs, and stable isotopes and fatty acids of the squid’s ovary.ResultsThe reproductive energy (the sum of the energy accumulated in ovary, nidamental glands and oviduct eggs) increased significantly with maturation. The ovary nitrogen stable isotopes (δ15N) showed a significant increase with maturation, but the increase by maturity stage was not equal to the typical enrichment of about 3‰ per trophic level. Isotopic niche width showed an increasing trend with maturation, and isotopic niche space exhibited greater overlap at advanced maturity stages. The relative amounts of 16:0, 20:5n3 and 20:4n6 in the ovary, tracing for carnivores and top predators, increased after the onset of maturation. The overall fatty acid profiles of the ovary showed significant differences among maturity stages, but obvious overlaps were found for mature squids. Mixed-effects model results revealed that reproductive energy was positively correlated with δ15N values. The reproductive energy was also positively related to the relative amounts of 18:0 and 20:4n6, respectively tracing for herbivores and top predators.ConclusionsOur results validate that the squid shifts to feed on higher trophic prey for reproduction as energy demand increases once maturation commences. However, the squid does not shift feeding habits at a trophic level but instead broadens prey spectrum, coupled with increasing intake of higher trophic prey items, to meet the energy demand for reproduction. Such energy acquisition strategy may be selected by the squid to maximize reproductive success by balancing energy intake and expenditure from foraging, warranting future studies that aim to clarify such strategy for reproduction among semelparous species.

Rock structure drives the taxonomic and functional diversity of endolithic microbial communities in extreme environments.

Endolithic (rock-dwelling) microbial communities are ubiquitous in hyper-arid deserts around the world and the last resort for life under extreme aridity. These communities are excellent models to explore biotic and abiotic drivers of diversity because they are of low complexity. Using high-throughput amplicon and metagenome sequencing, combined with X-ray computed tomography, we investigated how water availability and substrate architecture modulated the taxonomic and functional composition of gypsum endolithic communities in the Atacama Desert, Chile. We found that communities inhabiting gypsum rocks with a more fragmented substrate architecture had higher taxonomic and functional diversity, despite having less water available. This effect was tightly linked with community connectedness and likely the result of niche differentiation. Gypsum communities were functionally similar, yet adapted to their unique micro-habitats by modulating their carbon and energy acquisition strategies and their growth modalities. Reconstructed population genomes showed that these endolithic microbial populations encoded potential pathways for anoxygenic phototrophy and atmospheric hydrogen oxidation as supplemental energy sources.

Reliability-constraint energy acquisition strategy for electricity retailers

Electricity retailers desire to specify the energy acquisition strategy and selling prices in a way that maximize the expected profit, and convince consumers to choose them as the energy provider. Reducing selling price decreases retailers’ income, and vice versa. Moreover, the higher selling price increases clients’ switching probability to rivals that reduces the retailer’s expected income. Therefore, the retailer faces a tradeoff between selling prices and clients’ consumption. Additionally, fluctuations of wholesale prices, random demand, unexpected failures of self-generation facilities, and risk of rivals’ strategies are other difficulties faced by retailers, and these uncertainty resources affect their profits. This paper presents a fuzzy Information Gap Decision Theory (IGDT) based framework for electricity retailers to specify the energy acquisition strategy. Uncertainty of wholesale price is modeled via unknown bounded intervals. Additionally, the Point Estimate Method (PEM) is proposed to cope with the uncertainty of rivals’ strategies. Clients’ reaction to retail-selling prices is incorporated into the proposed framework via fuzzy numbers. In order to model the availability of generating units, a novel scheduling framework considering the repair time for failed units, in addition to repair cost and forced outage rate (FOR) is presented in this research. Finally, IGDT methodology is applied to determine the retailer’s energy acquisition strategy based on financial risk preferences. Performance of proposed model is evaluated via a case study, and the numerical results are discussed.

Stochastic risk-constraint pricing strategy of electricity retailers based on Dempster-Shafer evidence theory

This paper investigates a bi-level stochastic energy acquisition strategy for electricity retailers with self-generation facilities to supply clients' demand from various resources of energy. The main propose of the presented work is modeling clients' switching behavior based on uncertainties of rival retailers' strategy and wholesale prices. The upper sub-problem models wholesale price fluctuations and determines retailer's participation levels in the forward and wholesale markets as well as scheduling of self-generation facilities based on the minimum supply cost. In the lower sub-problem, the Dempster-Shafer evidence theory (DSET) is applied to determine the retail selling price based on rivals' strategies and clients' switching tendency. DSET defines two belief and plausibility functions to evaluate the possibility of accepting selling prices by clients. According to the retailer's defined belief level and the minimum expected cost, the selling price is calculated in the lower sub-problems. Finally, a case study is used to show the performance of proposed method.

Patterns of Bacterial and Archaeal Gene Expression through the Lower Amazon River

Analysis of metatranscriptomic and metagenomic datasets from the lower reaches of the Amazon River between Obidos and the river mouth revealed microbial transcript and gene pools dominated by Actinobacteria, Thaumarchaeota, Bacteroidetes, Acidobacteria, Betaproteobacteria, and Planctomycetes. Three mainstem stations spanning a 625 km reach had similar gene expression patterns (transcripts gene copy-1) across a diverse suite of element cycling genes, but two tributary-influenced stations at the mouth of the Tapajos River and near the Tocantins River at Belem had distinct transcriptome composition and expression ratios, particularly for genes encoding light-related energy capture (higher) and iron acquisition and ammonia oxidation (lower). Environmental parameters that were useful predictors of gene expression ratios included concentrations of lignin phenols, suspended sediments, nitrate, phosphate, and particulate organic carbon and nitrogen. Similar to the gene expression data, these chemical properties reflected highly homogeneous mainstem stations punctuated by distinct tributary-influenced stations at Tapajos and Belem. Although heterotrophic processes were expected to dominate in the lower Amazon, transcripts from photosynthetic bacteria were abundant in tributary-influenced regions, and transcripts from Thaumarcheota taxa genetically capable of chemosynthetic ammonia oxidation accounted for up to 21% of the transcriptome at others. Based on regressions of transcript numbers against gene numbers, expression ratios of Thaumarchaeota populations were largely unchanged within the mainstem, suggesting a relatively minor role for gene regulation. These quantitative gene and transcript inventories detail a diverse array of energy acquisition strategies and metabolic capabilities for bacteria and archaea populations of the world’s largest river system.

Day–night ecophysiology of the photosymbiotic bioeroding sponge Cliona orientalis Thiele, 1900

Marine bioerosion is projected to increase under future environmental conditions, and interest in investigating the ecological roles of bioeroding sponges has grown substantially over recent years. Cliona orientalis Thiele, 1900 is an important bioeroding sponge on Indo-Pacific coral reefs that belongs to the Cliona viridis species complex, which is a group of Clionaidae that are symbiotic with dinoflagellates of the genus Symbiodinium. The present study aimed to investigate the intracellular Symbiodinium and the holosymbiont of C. orientalis under a day–night cycle. Measurements of chlorophyll fluorescence confirmed significant day–night relocation of Symbiodinium by C. orientalis, in which Symbiodinium mostly resided at the surface during the day to enhance light availability. Under the light regime within C. orientalis, Symbiodinium displayed efficient photosynthesis as indicated by its oxygen production rate. At night, Symbiodinium was drawn deeper into the sponge. As a holosymbiont, C. orientalis did not significantly change net uptake of heterotrophic carbon between day and night. During the day, the host presumably received autotrophic carbon translocated from Symbiodinium and displayed faster bioerosion measured as dissolution of calcium carbonate. The present findings advance our understanding of how diurnal rhythms may influence energy acquisition strategies and ecological performance of a sponge–photosymbiont association.

Oil and gas cooperation between China and Central Asia in an environment of political and resource competition

This paper investigates Central Asia’s oil and gas resources, special geopolitics and energy competition, and approaches, challenges and prospects in cooperation between China and Central Asia. The objective is to propose measures for oil and gas cooperation between China and Central Asia. Central Asia is rich in oil and gas resources. Its remaining recoverable reserves of crude oil and natural gas account for 1.9% and 10.6 %, respectively, of the world’s total reserves. Moreover, there is great exploration and development potential. As a strategic channel connecting Eurasia, Central Asia has a prominent geopolitical status. Many powerful countries such as the United States, Russia and China, as well as Europe, have an intense energy competition in Central Asia. In the oil and gas cooperation with Central Asia, the China National Petroleum Corporation (CNPC) focuses on establishing a coordination group, promoting overall oil and gas business opportunities and sustainable development, innovating and applying specialty engineering technology and improving project economic benefits. Through its efforts over the last nearly two decades, the China National Petroleum Corporation has completed a 50-million-tonne a year oil and gas production centre in Central Asia and oil and gas pipelines passing through multiple countries, becoming an important channel for securing China’s energy imports. If appropriate measures are taken in the ‘Thirteenth Five-Year Plan’ period or later, the China National Petroleum Corporation will develop a 100-million-tonne p.a. oil and gas production centre in Central Asia and a strategic oil and gas import channel exceeding this amount of production. This cooperation between China and Central Asia is however faced with the following challenges: increasing multinational competition uncertainty, potential risks in the political systems of Central Asian countries, frequently occurring violence and also resource policy tightening in Central Asia. To further oil and gas cooperation with Central Asia, it is recommended that China should develop an energy acquisition strategy, assign a regional energy ambassador, enhance oil and gas supply by mergers and acquisitions, establish regional multinational subsidiaries and improve its risk prevention system.

Temperature and water flow influence feeding behavior and success in the barnacle Balanus glandula

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 507:207-218 (2014) - DOI: https://doi.org/10.3354/meps10848 Temperature and water flow influence feeding behavior and success in the barnacle Balanus glandula Michael T. Nishizaki1,2,*, Emily Carrington1,2 1Department of Biology, University of Washington, Seattle, WA 98195, USA 2Friday Harbor Laboratories, Friday Harbor, WA 98250, USA *Corresponding author: mnishiza@uoguelph.ca ABSTRACT: Suspension feeding is a common energy acquisition strategy for many marine organisms. Conditions in the fluid environment (e.g. flow, temperature) can influence both the flux of particles past an organism and the efficiency with which organisms retain those particles. We investigated feeding behavior in the barnacle Balanus glandula under a range of water velocities and temperatures using gut dissections to directly quantify capture rates of food particles. Overall, the percentage of barnacles observed beating was typically high (68 ± 3%), yet gut dissections confirmed that a far lower percentage had actually ingested food particles (hydrated Artemia cysts; 22 ± 3%). This discrepancy suggests that cirral activity may serve other functions and that simple behavioral descriptions provide a poor proxy for barnacle feeding rate. Although the delivery of cysts to the cirral net and cyst capture rates peaked at intermediate water velocities (7.5 to 20 cm s-1), capture efficiency (the ratio of cysts captured to cysts encountered) was highest under the slowest flow (1 cm s-1). Model analysis demonstrated that detailed characterization of cirral beating behavior is required to accurately predict patterns of flow-dependent cyst capture. Barnacles also showed a clear thermal optimum between 10 and 15°C in both capture rate and efficiency. At high temperatures (25°C), feeding was reduced due to an increase in abbreviated beating behavior, whereas at low temperatures (5°C) reduced capture was likely a consequence of slower beating rate. Again, only when beating behavior was incorporated into models were patterns of temperature-dependent cyst capture accurately predicted. These results suggest that the limits to feeding success are not simply biophysical, but also behavioral in nature. KEY WORDS: Suspension feeding · Barnacles · Water flow · Thermal tolerance Full text in pdf format PreviousNextCite this article as: Nishizaki MT, Carrington E (2014) Temperature and water flow influence feeding behavior and success in the barnacle Balanus glandula. Mar Ecol Prog Ser 507:207-218. https://doi.org/10.3354/meps10848 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 507. Online publication date: July 17, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Minke whales maximise energy storage on their feeding grounds

Seasonal trends in energy storage of the minke whale (Balaenoptera acutorostrata), a capital breeder, were investigated in Iceland, a North Atlantic feeding ground. The aim was to better understand the energy acquisition strategies of minke whales and the energetic costs that different reproductive classes face during the breeding season. We modelled total blubber volume, using blubber thickness and morphometric measurements of individual whales. Blubber volume was influenced by body length, and was higher for pregnant females than mature whales. Blubber volume increased linearly through the feeding season at the same rate for mature (mean ± s.e.m.=0.0028 ± 0.00103 m(3) day(-1); N=61 male, 5 female) and pregnant whales (0.0024 ± 0.00100 m(3) day(-1); N=49), suggesting that minke whales aim to maximise energy storage while on the feeding grounds. The total amount of blubber accumulated over the feeding season (0.51 ± 0.119 m(3) for mature and 0.43 ± 0.112 m(3) for pregnant whales), together with energy stored as muscle and intra-abdominal fats, constitutes the total amount of energy available for reproduction (fetus development and lactation) on the breeding grounds, as well as migration, daily field metabolic rates, growth and body maintenance. No seasonal variation was observed for immature whales (N=4 male, 12 female), suggesting that they are investing most of their excess energy into growth rather than reproduction, in order to reach the length of sexual maturity faster and start reproducing earlier. Our novel modelling approach provides insight into large whale bioenergetics and life history strategies, as well as the relationship between single-site measurement of blubber thickness and total blubber volume.

China's Strategy for Energy Acquisition in the Middle East: Potential for Conflict and Cooperation With the United States

In this article, the authors examine China's evolving energy strategy in the Middle East, particularly in the three countries that have the largest energy reserves and form the epicenter of the U.S.‐China rivalry: Saudi Arabia, Iran, and Iraq. With $3 trillion in foreign currency reserves, Beijing is increasingly using its cash to secure future long‐term access to energy in the region. Through energy‐backed loans, as well as upstream and downstream joint ventures, China's policy banks and its national oil companies are pumping up the volume of oil and gas that will flow from the Middle East to the mainland in the 21st century. At the same time, Beijing is embedding itself deeply in the economies of these major oil‐producing states through expanded bilateral trade involving multiple sectors of the Chinese economy. Beijing's monetary strength, coupled with its lack of military involvement and political baggage in the region, has China poised to benefit from its expansive access to the region's energy resources. This article critically examines the political implications of China's energy acquisition strategy, the potential for conflict as well as cooperation with the United States, and the possibility of the realignment of great powers in the Middle East.

A Multiperiod Energy Acquisition Model for a Distribution Company With Distributed Generation and Interruptible Load

This paper presents a multiperiod energy acquisition model for a distribution company (Disco) with distributed generation (DG) and interruptible load (IL) in a day-ahead electricity market. Assuming that cost information for individual generation companies (Gencos) and Discos is known, the Disco's energy acquisition strategy is modeled as a bilevel optimization problem with the upper subproblem representing individual Discos and the lower subproblem representing the independent system operator (ISO). The upper subproblem maximizes individual Discos' revenues. The lower subproblem simulates the ISO's market clearing problem that minimizes generation costs and compensation costs for interrupting load. The bilevel problem is solved by a nonlinear complementarity method. An 8-bus system is employed to illustrate the proposed model and algorithm. In particular, the roles of DGs and ILs to alleviate congestion are analyzed