Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

This book describes the environment and behaviour patterns of the Weddell seal. Based on his numerous expeditions to the Antarctic, Dr Kooyman has analysed the seal's diving physiology and acoustical biology. The seal's remarkable adaptation to its environment is evidenced in its ability to dive to 600 meters and return without ill effect and to remain submerged for more than one hour, even though it is an air-breathing animal. The seal holds a unique niche in the world's ecology; it occupies the most southern latitude of any mammal on a permanent basis. The study of this seal has provided important insights into methods of animal navigation, respiration and metabolism. Dr Kooyman is well known as an authority on the Weddell seal. During his fifteen trips to the Antarctic since 1961, he has studied the seal extensively. This book should appeal to marine biologists, animal physiologists and to all those with a serious interest in natural history and life in the Antarctic.

Weddell seal

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Our relationships with marine mammals are complex. We have used them as resources, and in some places this remains the case; viewed them as competitors and culled them (again ongoing in some localities); been so captivated and intrigued by them that we have taken them into captivity for our entertainment; and developed a lucrative eco-tourism activity focused on them in many nations. When we first envisaged this special topic, we had two overarching aims: Firstly, we hoped to generate critical evaluation of some of our relationships with these animals. Secondly, we hoped to attract knowledgeable commentators and experts who might not traditionally publish in the peer-reviewed literature. We were also asking ourselves a question about what responsibility mankind might have to marine mammals, on our rapidly changing planet? The answer to the question; can, or should, humans have responsibility for the lives of marine mammals when they are affected by our activities? - is, in our opinion, ‘yes’ – and the logical progression from this question is to direct research and effort to understand and optimise the actions, reactions and responses that mankind may be able to take. We hope that the papers in this special issue bring some illumination to a small selection of topics under this much wider topic area, and prove to be informative and stimulating.

Bycatch --- Whale --- Marine Debris --- Dolphin --- Whaling --- Seal --- Cetacean society --- Human interaction --- Culture --- Bycatch --- Whale --- Marine Debris --- Dolphin --- Whaling --- Seal --- Cetacean society --- Human interaction --- Culture

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Au cours des dernières décennies, l’Arctique semble subir des changements fondamentaux principalement dus au réchauffement de la planète. Ces nouvelles conditions climatiques pourraient avoir une incidence sur les cycles biologiques et l'exposition au mercure (Hg) dans le biote arctique. En effet, il semble que le mercure dans l’environnement arctique ait atteint des concentrations extrêmement élevées. Étant donné que le mercure est bioaccumulé et bioamplifié le long du réseau alimentaire, les niveaux de mercure sont plus élevés chez les principaux prédateurs. Le phoque à capuchon (Cystophora cristata) est un mammifère marin de l'Arctique doté d'adaptations physiologiques extrêmes et occupant une position relativement importante dans la chaîne alimentaire. Cela en fait une espèce clé idéale pour évaluer le cycle de mercure chez les prédateurs de l'Arctique. Notre hypothèse est que les importantes spécialisations développées par les prédateurs marins de l’Arctique pour survivre dans un environnement froid et instable pourraient exacerber les éventuels changements de l’accumulation de mercure dans leurs tissus.
Ce document vise à évaluer les concentrations de mercure, en 13C, 15N et 34S chez les phoques à capuchon, en se concentrant sur la sous-population du centre-est du Groenland de 1985 à 2019. Cette évaluation nous permettra de comprendre les impacts du changement climatique sur l'écologie trophique du phoque à capuchon et sur l'évolution des concentrations de mercure dans le temps.
Les concentrations de mercure et les valeurs en en 13C, 15N et 34S ont été analysées dans les muscles et le poil du phoque à capuchon. L’indice NAO et l’étendue des glaces ont été utilisés comme indicateurs indirects du changement climatique dans l’Arctique.

Globalement, le changement climatique a un impact significatif sur l'écologie trophique et l'accumulation de mercure chez les phoques à capuchon. En effet, les valeurs en en 13C, 15N et 34S et les niveaux de T-Hg étaient significativement corrélés à la diminution de la glace.
La diminution des valeurs 13C, 15N et de T-Hg de 1985 à 2018 semble être corrélée à: (1) une modification sensible du régime alimentaire et de l'utilisation de l'habitat par le phoque à capuchon en réponse à des changements du cycle et biomasse de leurs proies; ou (2) la diminution de l'étendue des glaces semble transformer l'Arctique en un environnement plus «extracôtier».

phoque à capuchon Hooded seal mercure isotopes --- Sciences du vivant > Sciences aquatiques & océanologie

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Harbour seals bioaccumulate contaminants such as metal trace elements (MTEs), which are present in the North Sea and consequently they are often used as bioindicators for chemical exposure. For this reason, it is increasingly necessary to use biomarkers which are early indicators of exposure to toxic substances. The MTEs are known to cause oxidative stress, which is the result of an imbalance between the amount of reactive oxygen species (ROS) produced and the implementation of antioxidants defenses. This could cause lipid peroxidation and ultimately the death of the cell. Therefore, levels of antioxidants defenses could be good biomarkers to assess MTEs exposure. While oxidative damage could be a good biomarker of effects.
The aim of this study was to evaluate the relationship between the levels of MTEs contamination and biomarkers of exposure and effect. Selected biomarkers were: malondialdehyde (TBARS), total thiols, total glutathione (tGSH), Se dependent peroxydases (SeGPx), total glutathione peroxidases (GPx) and triglycerides. The first step of this study consisted to optimize assay protocols for those oxidative stress biomarkers in order to allow their assessments in the harbour seal serum. All biomarkers assays could be developed and analyzed by spectrophotometry.
In a second part, biomarkers analyses were conducted in a case study aiming to link their responses to contamination of MTEs in harbour seals of the Wadden Sea. The results demonstrated that MTEs concentrations in blood cells were significant different between males and females concerning Hg and Zn, with lower concentrations in females. Although, it has not been possible to identify how MTEs influenced oxidative stress in harbour seals, the lack of correlation between Se and SeGPx may indicate that Se is not limiting for harbour seals. However, a positive correlation was noted between Ni and GPx activities, probably caused by the formation of ROS by Ni. Moreover, the Hg contamination had potentially depleted tGSH in females (negative correlation) and finally, lipid peroxidation was increasingly important when it was exposed to Ni and Pb, however, this was only observed in March and not in October. An increase of lipid peroxidation could thus be due to environmental factors. Finally, even if the measurement of biomarkers is correct, the conservation of the serum may have permitted that few correlations were found between ETMs and biomarkers.

biomarkers, oxidative stress, metallic exposure, harbour seal, the North Sea --- Sciences du vivant > Sciences de l'environnement & écologie --- Sciences du vivant > Multidisciplinaire, généralités & autres

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

A heat pump system can produce an amount of heat energy that is greater than the amount of energy used to run the heat pump system. Thus, a heat pump system is considered to be a machine system that can use energies efficiently, as is the load leveling air-conditioning system utilizing unutilized energies at high levels. Adaptations of gas turbines for industrial, utility, and marine-propulsion applications have long been accepted as means for generating power with high efficiency and ease of maintenance. Cogeneration with gas turbine is frequently defined as the sequential production of useful thermal energy and shaft power from a single energy source. For applications that generate electricity, the power can either be used internally or supplied to the utility grid. This Special Issue intends to provide an overviews of the existing knowledge related with various aspects of “Small-Scale Energy Systems with Gas Turbines and Heat Pumps”, and contributions on, but not limited to the following subjects were encouraged: wake of stator vane to improve sealing effectiveness; gas turbine cycle with external combustion chamber for prosumer and distributed energy systems; computational simulation of gas turbine engine operating with different blends of biodiesel; experimental methodology and facility for the engine performance and emissions evaluation using jet and biodiesel blends; experimental analysis of an air heat pump for heating service; hybrid fuel cell-Brayton cycle for combined heat and power; design analysis of micro gas turbines in closed cycles. Seven papers were published in the Special Issue out of a total of 12 submitted.

History of engineering & technology --- wave-shaped rim seal --- sealing effectiveness --- radial seal --- gas turbine --- computational fluid dynamics --- biofuels --- sustainable power generation --- microturbines --- gas turbine engine --- two-spool turboprop engine --- PT6A engine --- aero-thermal model --- Matlab-Simulink --- bio-diesel --- start-up transient --- biodiesel --- turbojet --- energy performance --- emissions --- aviation --- hardware-in-the-loop --- heat pumps --- dynamic simulation --- experimental performances --- control strategy --- partial loads --- on-off cycles --- building dynamics --- building-heating system coupling --- supercritical CO2 --- combined heat and power --- flame-assisted fuel cells --- carbon sequestration --- solid oxide fuel cell --- closed cycle gas turbine --- different working fluids --- thermodynamic analysis --- design of turbines --- design of compressors --- wave-shaped rim seal --- sealing effectiveness --- radial seal --- gas turbine --- computational fluid dynamics --- biofuels --- sustainable power generation --- microturbines --- gas turbine engine --- two-spool turboprop engine --- PT6A engine --- aero-thermal model --- Matlab-Simulink --- bio-diesel --- start-up transient --- biodiesel --- turbojet --- energy performance --- emissions --- aviation --- hardware-in-the-loop --- heat pumps --- dynamic simulation --- experimental performances --- control strategy --- partial loads --- on-off cycles --- building dynamics --- building-heating system coupling --- supercritical CO2 --- combined heat and power --- flame-assisted fuel cells --- carbon sequestration --- solid oxide fuel cell --- closed cycle gas turbine --- different working fluids --- thermodynamic analysis --- design of turbines --- design of compressors