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The cisco Coregonus artedi is a coldwater fish that is distributed throughout much of Canada and the northern United States, including the Laurentian Great Lakes. Cisco historically supported large commercial fisheries in the Great Lakes during the late 1800s and early 1900s, but many populations declined and never recovered. Restoration efforts focusing on re-establishing cisco in the Great Lakes are underway, but increasing water temperatures may hinder these efforts. Therefore, we examined aerobic scope and thermal tolerance of allopatric cisco populations from different latitudes and habitats to determine if a southern latitude population (Crooked Lake, Indiana, USA) near the southern edge of cisco distribution was better adapted to withstand warmer water temperatures than a northern latitude population (Les Cheneaux Islands, Michigan, USA; Lake Huron). As expected, both stocks demonstrated increases in metabolic rates and absolute aerobic scope with increased temperature. Northern cisco had significantly lower aerobic scope compared to southern cisco at both treatment temperatures of 10 and 13 °C. Both cisco stocks had high thermal tolerances when challenged by temperatures increased to 20 and 23 °C but low tolerances at 26 °C. Cisco thermal tolerances increased with acclimation temperature, but we did not detect a difference in thermal tolerances between northern and southern cisco. Although southern cisco had higher capacity for aerobic metabolism, both stock sources had high thermal tolerances at the upper end of their thermal limits. Therefore, either population would be likely suitable for reintroduction into Great Lakes habitats, even with expected warming in the future. [ABSTRACT FROM AUTHOR]

Understanding how birds annually allocate energy to cope with changing environmental conditions and physiological states is a crucial question in avian ecology. There are several hypotheses to explain species' energy allocation. One prominent hypothesis suggests higher energy expenditure in winter due to increased thermoregulatory costs. The "reallocation" hypothesis suggests no net difference in seasonal energy requirements, while the "increased demand" hypothesis predicts higher energy requirements during the breeding season. Birds are expected to adjust their mass and/or metabolic intensity in ways that are consistent with their energy requirements. Here, we look for metabolic signatures of seasonal variation in energy requirements of a resident passerine of a temperate-zone (great tit, Parus major). To do so, we measured whole-body and mass-independent basal (BMR), summit (M sum), and field (FMR) metabolic rates during late winter and during breeding in Belgian great tits. During the breeding season, birds had on average 10% higher whole-body BMR and FMR compared to winter, while their M sum decreased by 7% from winter to breeding. Mass-independent metabolic rates showed a 10% increase in BMR and a 7% decrease in M sum from winter to breeding. Whole-body BMR was correlated with M sum , but this relationship did not hold for mass-independent metabolic rates. The modest seasonal change we observed suggests that great tits in our temperature study area maintain a largely stable energy budget throughout the year, which appears mostly consistent with the reallocation hypothesis. • Great tits showed minor differences in seasonal energy expenditure. • Mass-independent M sum was slightly but significantly higher during winter. • Results are broadly consistent with the reallocation hypothesis. [ABSTRACT FROM AUTHOR]

Understanding how evolutionary variation in energetic metabolism arises is central to several theories in animal biology. Basal metabolic rate (BMR) –i.e., the minimum rate of energy necessary to maintain thermal homeostasis in endotherms– is a highly informative measure to increase our understanding, because it is determined under highly standardized conditions. In this study we evaluate the relationship between taxa- and mass-independent (residual) BMR and ten environmental factors for 34 subterranean rodent species. Both conventional and phylogenetically informed analyses indicate that ambient temperature is the major determinant of residual BMR, with both variables inversely correlated. By contrast, other environmental factors that have been shown to affect residual BMR in endotherms, such as habitat productivity and rainfall, were not significant predictors of residual BMR in this group of species. Then, the results for subterranean rodents appear to support a central prediction of the obligatory heat model (OHM), which is a mechanistic model aimed to explain the evolution of residual BMR. Specifically, OHM proposes that during the colonization of colder environments, individuals with greater masses of metabolically expensive tissues (and thus with greater BMR) are favored by natural selection due to the link between greater masses of metabolically expensive tissues and physiological capacities. This way, natural selection should establishes a negative correlation between ambient temperature and both internal organ size and residual BMR. [ABSTRACT FROM AUTHOR]

Thermodynamics is a major factor determining rates of energy expenditure, rates of biochemical dynamics, and ultimately the biological and ecological processes linked with resilience to global warming in ectothermic organisms. Nonetheless, whether ectothermic organisms exhibit general adaptive metabolic responses to cope with worldwide variation in thermal conditions has remained as an open question. Here we combine a model comparison approach with a global dataset of standard metabolic rates (SMR), including 1,160 measurements across 788 species of aquatic invertebrates, insects, fishes, amphibians and reptiles, to investigate the association between metabolic rates and environmental temperatures in their respective habitats. Our analyses suggest that variation in SMR after removing allometric and thermodynamic effects is best explained by the temperature range encountered across seasons, which always provided a better fit than the average temperature for the hottest and coldest month and mean annual temperatures. This pattern was consistent across taxonomic groups and robust to sensitivity analyses. Nonetheless, aquatic and terrestrial lineages responded differently to seasonality, with SMR declining – 6.8% °C−1 of thermal range across seasons in aquatic organisms and increasing 2.8% °C−1 in terrestrial organisms. These responses may reflect alternative strategies to mitigate the impact of increments in warmer temperatures on energy expenditure, either by means of metabolic reduction in thermally homogeneous water bodies or effective behavioral thermoregulation to exploit temperature heterogeneity on land. • Energy turnover rates in ectothermic organisms are sensitive to environmental temperatures, yet it remains unclear how different lineages adapt to contrasting thermal environments. • We studied how metabolism varies geographically across ectotherms taxa, providing evidence of adaptation to temperature variability across ectothermic lineages. • Whereas terrestrial organisms exhibit elevated metabolic rates to take advantage of environmental heterogeneity in temperatures, aquatic organisms adopt a strategy of metabolic reduction to save energy during warm seasons. [ABSTRACT FROM AUTHOR]

Precision ventilation is used in open-plan offices to establish micro-climate zones according to the metabolic requirements of its occupants. The aim of this study is to determine design criteria and highlight the opportunities and limitations for precision ventilation in large-scale offices. The simulations and experiments were conducted under steady state conditions with fixed airflow from all active chilled beams (ACBs) and constant room temperatures. A temperature difference of 3.5K was maintained between supply and room air in all cases with and without occupants. Results showed that precision ventilation can simultaneously establish low-level (<0.15 m/s), medium-level (<0.45 m/s), and high-level (<0.65 m/s) air velocity zones in the same shared office space such that occupants with different metabolic rates had Predicted Mean Vote (PMV) values maintained within the acceptable limit. The establishment of a single air velocity zone in an open-plan office layout without influencing air velocities of other zones was achieved by lowering the airflow rates of two ACBs by 35%. The vertical and horizontal temperature uniformity was maintained with this precision ventilation system with draught rates of less than 20% for occupants with normal metabolic rates. Comparative analysis using precision ventilation with and without occupants showed that targeted air velocity distribution in the room can be negatively influenced by the absence of any heat sources in any zone. An annual energy saving of up to 15% was achieved by raising the cooling setpoint temperature from 23 °C to 25 °C. • Precision ventilation strategy is applied to the large-scale open-plan officeto establish design criteria for multiple ACBs working. • Experimental and simulation results showed more stable targeted airflow distribution in the case of occupants in the room compared to without occupants. • The Draught Rate and Vertical Temperature Difference for occupants in all zones remain within acceptable limits even with the formation of high air velocity zones. • An annual energy saving of up to 15% was achieved by raising the cooling setpoint temperature from 23 °C to 25 °C. [ABSTRACT FROM AUTHOR]

This study investigated the effect of chronic temperature acclimation (24, 26, 28, 30, and 32 °C) on growth, aerobic metabolism, feeding, and gut evacuation rate of early juvenile spiny lobster, Panulirus ornatus (initial weight = 0.48 ± 0. 03 g) to determine thermal optima for growth and identify physiological constraints at high temperatures for this emerging aquaculture species. Groups of 7 juvenile lobsters were communally cultured (n = 4) for 45 days post-acclimation and solely fed on a formulated feed. Lobster specific growth rate (SGR), apparent feed intake (AFI), and specific feed consumption (SFC) displayed unimodal response to temperature peaking at 28.0, 27.9, and 26.2 °C, respectively. Similarly, survival had a significant quadratic relationship with temperature; however, it displayed an inverse relationship to SGR, AFI, and SFC where the lowest survival was found at 29.1 °C. Continuous exponential increases in lobster standard, routine and maximum metabolic rates, and aerobic scope were observed up to a maximum non-lethal temperature of 32 °C. Gastrointestinal evacuation rate (GIER) (>96%) increased minimally between 24 and 30 °C from 2.5 h to 2.9 h and substantially rose to 5.1 h at 32 °C. While the feed conversion ratio improved with increasing temperature, the temperature optimum for metabolic feeding efficiency closely matched specific growth rate and apparent feed intake. These findings show that optimum temperature for growth performance of juvenile P. ornatus does not align with maximum aerobic scope, rather growth was limited by prolonged GIER (up to 5.1 h) at high temperatures 32 °C which constrained food consumption. These findings contribute to the growing body of literature debating the universality of aerobic scope to define physiological thermal boundaries of aquatic ectotherms suggesting thermal performance of lobsters under sub-lethal temperatures to be regulated by feed intake and driven by digestive processes such as GIER. Future research should focus on lobster feed formulation and its influence on digestive processes such as GIER, foregut evacuation, and digestibility which may influence the thermal tolerance of spiny lobsters in culture. • Thermal influence on performance of hatchery reared juvenile P. ornatus fed solely on formulated feed. • Thermal optimum for maximum growth (SGR) of juvenile hatchery reared P. ornatus is 28 °C. • Growth of juvenile hatchery reared P. ornatus are physiologically constraint by feeding, rather than by OCLTT theorem. • Prolonged GIER for P. ornatus at high temperature treatments correlated to reduced feeding and growth beyond thermal optimum. [ABSTRACT FROM AUTHOR]

The background colour of aquaculture tanks is normally chosen based on practical experience and/or observations of fish behaviour and the growth rates achieved. However, some farmed species, including turbot, are sentient and can show a preference for a particular environment. In the current study, a self-referent colour preference device was developed and the self-referent colour preference of farmed fish investigated. In experiment 1, the background colour preference of juvenile turbot cultured under a grey background for > 3 months post-incubation was evaluated. Based on these results, in experiment 2, juvenile turbot were adapted to blue, pink, white, or black backgrounds for 50 days and their preferences established. Meanwhile, the growth rates, feed intake, and metabolic rates (including oxygen consumption rate, and ammonia excretion rate) of the turbot were evaluated. The results showed that turbot farmed under a grey background, or after long-term white, blue, pink and black colour adaptation, always displayed a preference for a white background and a dislike for black, red, or brown backgrounds, although their body colour was greyish. Long-term adaptation influenced the frequency of juveniles selecting white, black, pink or blue backgrounds. They showed the highest growth rate, feed intake, and metabolic rates under blue and white backgrounds, and the lowest under a black background in accordance with their preferences shown in experiment 1. Although it is unclear how turbot determine their self-referent colour preferences over such a short period of time, these results indicate that dark colours are unsuitable for the aquaculture of turbot culture in terms of the welfare of the fish. [ABSTRACT FROM AUTHOR]

Given that our climate is rapidly changing, Physiological Ecologists have the critical task of identifying characteristics of species that make them either resilient or susceptible to changes in their natural air temperature regime. Because climate change models suggest that heat events will become more common, and in some places more extreme, it is important to consider how extreme heat events might affect the physiology of a species. The implications of more frequent heat wave events for birds have only recently begun to be addressed, however, the impact of these events on the cellular physiology of a species is difficult to assess. We have developed a novel approach using dermal fibroblasts to explore how short-term thermal stress at the whole animal level might affect cellular rates of metabolism. House sparrows, Passer domesticus were separated into a “control group” and a “heat shocked” group, the latter acclimated to 43 °C for 24 h. We determined the plasticity of cellular thermal responses by assigning a “recovery group” that was heat shocked as above, but then returned to room temperature for 24 h. Primary dermal fibroblasts were grown from skin of all treatment groups and the pectoralis muscle was collected. We found that glycolysis (ECAR) and oxygen consumption rates (OCR), measured using a Seahorse XF 96 analyzer, were significantly higher in the fibroblasts from the heat shocked group of House sparrows compared with their control counterparts. Additionally, muscle fiber diameters decreased and, in turn, Na + –K + -ATPase maximal activity in the muscle significantly increased in heat shocked sparrows compared with birds in the control group. All of these physiological alterations due to short-term heat exposure were reversible within 24 h of recovery at room temperature. These results show that acute exposure to heat stress significantly alters the cellular physiology of sparrows, but that this species is plastic enough to recover from such a thermal insult within 24 h. [ABSTRACT FROM AUTHOR]

The Wandering Albatross ( Diomedea exulans ) and other seabirds exhibit a growing pattern that includes a period of body mass decrease before fledging. Several hypotheses have been suggested to explain it without success. We hypothesized that: 1) chicks and adults have similar metabolic traits regulating assimilation, growth and maturation; 2) there is a difference in locomotion effort between chicks and adults, and 3) chicks are exposed to a decline in food availability before fledging. This set of hypotheses allows for an energy surplus to be available and stored in reserve during the first months of development, explaining the mass recession that starts before fledging and the fact that adults keep a lower weight than fledglings, throughout the rest of their life span. To test this set of hypotheses we applied the Dynamic Energy Budget (DEB) theory. Using a small set of life-history traits and growth curves we parameterized the DEB standard model. We confirmed this set of hypotheses and estimated the pattern of decline in food availability that explains mass recession. An assessment of the daily energy intake was also performed. The implications related to that energy flux and diet composition are discussed based on current knowledge. The DEB model for the Wandering Albatross also provided estimates for the adult daily food ingested by adults (464.06 kJ kg − 1 d − 1 ), fasting capacity (25 d), Field Metabolic Rate (4.29 W kg − 1 ) and resting metabolic rate (2.87 W kg − 1 ). These values are consistent with the averages obtained in the field, suggesting that DEB may be useful to provide good estimations on a broader scale. [ABSTRACT FROM AUTHOR]

Abstract: Peripheral blood lymphocytes isolated from healthy human donors'' buffy coat were cultured in membrane bio-reactors (MBR) designed in two different configurations: a conventional hollow-fiber (HF) bundle of modified polyetheretherketone (PEEK-WC) arranged in parallel, and a cross-assembled PEEK-WC and polyethersulfone (PES) HF membranes having different structural properties. Both bioreactors were experimentally compared in terms of metabolic activity of cultured cells, monitored over 8 days with respect to glucose uptake rate (GUR) and lactate production rate (LPR), and mathematically modelled by Computational Fluid Dynamics (CFD) method in order to investigate the impact of geometrical configuration and transport properties of biomaterials. The almost uniform trend of GUR from day 2 to day 7 (average of 0.0497 ± 0.0076 ng/h cell) and the low LPR (that decreased from an initial value of 2.92 ± 0.0055 pg/h cell to practically zero at day 8) provided evidence for superior performance of crossed-HFMBR in reproducing an optimal in vitro physiological environment with quite uniform concentration distribution of species in the extracellular space of the bioreactor and able to maintain lymphocyte viability and functions. The crossed HFMBR also resulted in an enhanced production of interleukin IL-2 over 8 days (average of 0.995 ± 0.25 pg/h/Mcell) and IL-10 in the first 3 days (average of 6.46 ± 0.28 pg/h/Mcell) which were up to one order of magnitude higher with respect to values measured in the parallel configuration. [Copyright &y& Elsevier]

Abstract: Developmental plasticity allows individuals to match their phenotype to the competitive environment they are most likely to encounter. Although there are numerous studies that demonstrate adaptive shifts in life-history and metric traits, we still have a poor understanding of whether internal physiological processes demonstrate plasticity and whether this plasticity supports life-history and metric traits. Here we use the Australian redback spider (Latrodectus hasselti), a species that demonstrates adaptive developmental shifts in response to the availability of females and the density of males, to examine the relationship between the routine metabolic rate (RMR) and the expression of size, body-condition and development rate. We reared immature males in three diet treatments, and in social environments that varied the presence/absence of females and the density of males and measured their RMR, weight, size and developmental rate at maturity. We show that although RMR decreased with decreasing resource abundance, RMR was positively correlated with the density of rivals. Moreover, RMR was not correlated with size or body-condition at maturity. Our results demonstrate that plasticity in the RMR supports plasticity in metric and life-history traits to create an integrated phenotype that matches the competitive environment. [Copyright &y& Elsevier]

Abstract: Despite the fact that microbial cells are unlikely to be found in the Martian soil in the near future, this paper is written on the assumption that some of the seasonally varying concentration of Martian methane is due to ongoing methanogenesis. It is first pointed out that life might have arisen on Mars first and been transported to Earth later. A case is made that an icy origin of life is more likely than a hot origin, especially if biomolecules take advantage of the high encounter rates and stability against hydrolysis, and that microorganisms feed on the ions that comprise eutectic solutions in ice. Although certain difficulties are avoided if RNA and DNA grow while adsorbed on clay grains, double strand-breaks of microbial DNA due to alpha radioactivity are a far greater threat to microbial survival on clay or other rock types than in ice. Developing a relation between the rate of microbial metabolism in ice and the experimentally determined rate of production of trapped gases of microbial origin, one can estimate the concentration of methanogens that could account for the methane production rate as a function of temperature of their habitat. The result, of order 1cellcm−3 in the Martian subsurface, seems an attainable goal provided samples are taken from at least 1 or 2m below the hostile surface of Mars. Instruments on NASA’s 2011 Mars Science Lab will measure stable isotopes for methane, water, and carbon dioxide, which on Earth served to distinguish abiotic, thermogenic, and microbial origins. Future measurements of chirality of biomolecules might also provide evidence for Martian life. [ABSTRACT FROM AUTHOR]

Abstract: Amethyst Sunbirds (Chalcomitra amethystina) occur over an altitudinal gradient within KwaZulu-Natal, South Africa, from the Drakensberg mountain range to the coast. Sunbirds were caught in summer (November–December 2006) at three altitudinal locations within KwaZulu-Natal; Underberg (1553m above sea level (asl)), Howick (1075m asl) and Oribi Gorge (541m asl). Summer oxygen consumption (VO2) was measured pre-acclimation at 5 and 25°C. After post-acclimation to 25°C and 660m for 6 weeks, VO2 measurements were taken at 8 different temperatures (15, 5, 10, 20, 30, 28, 25 and 33°C). Summer resting metabolic rates (RMR) differed significantly between altitudinal subpopulations of Amethyst Sunbirds. Summer basal metabolic rate was observed to decrease as altitude decreased. Differences between pre-acclimation RMR (representing natural acclimatization to summer conditions in the field) and post-acclimation RMR (to 25°C at 660m asl for 6 weeks) were large. In particular, Sunbirds from the Underberg subpopulation increased RMR by 80.9% at 5°C and 85.2% at 25°C post-acclimation. This summer research complemented an earlier study on altitudinal variation in Amethyst Sunbirds in winter. It again emphasized the need to acknowledge altitudinal differences between subpopulations and not just use species means, as species means do not fully incorporate the effect of phenotypic plasticity/flexibility. [Copyright &y& Elsevier]

As detected in warming and ocean acidification, global change can have profound impact on marine life. Its effects on seagrasses are becoming increasingly well-known, since several studies have focused on the responses of these species to global change conditions. However a few studies have assessed the combined effect of temperature and acidification on seagrasses. Overall in this study, the combined effects of increased ocean temperature and pH levels expected at the end of this century (+5 °C and pH 7.5) on Cymodocea nodosa from Canary Islands, were evaluated for one month through manipulative laboratory experiments. Growth, net production, respiration, gross primary production, chlorophyll-a concentration and its vulnerability to herbivory were quantified. Results showed a positive effect of decreased pH on growth and gross primary production, as well as greater vulnerability to consumption by the sea urchin Paracentrotus lividus. In contrast, increased temperature limited net and gross primary production. This study shows than in future scenarios, C. nodosa from the Canary Islands may be a losing species in the global change stakes. • Ocean acidification increase growth and gross primary production of Cymodocea nodosa. • The rise of temperature limited the net and gross primary production of Cymodocea nodosa. • A positive effect of decreased pH on greater vulnerability to consumption by Paracentrotus lividus. • A future scenario of climate change will affect metabolic rates of C. nodosa. • Different responses to climate change have been observed by C. nodosa from Canary Islands. [ABSTRACT FROM AUTHOR]

Abstract: Southern Africa is characterised by an unpredictable environment with daily and seasonal temperature fluctuations, thus posing challenging thermal conditions and increased energetic stress for endothermic vertebrates. Amethyst Sunbirds (Chalcomitra amethystina) are relatively large African sunbirds (15 g). They are considered non-migratory and thus have to cope with the temperature changes and physiological stresses a new season brings. This study compared altitudinal subpopulations and the seasonal shifts in metabolic parameters between and within the subpopulations in metabolic parameters. Amethyst Sunbirds were caught in summer and winter at three different altitudinal subpopulations; Underberg (1555 m asl), Howick (1075 m asl) and Oribi Gorge (541 m asl). Upon capture, metabolic rates of the sunbirds were measured indirectly by quantifying oxygen consumption (V̇O2) using flow through respirometry, at 5 and 25 °C. Birds then underwent a 6-week acclimation period at 25 °C on a 12 L: 12D cycle. V̇O2 was measured post-acclimation at 8 different temperatures (15, 5, 10, 20, 30, 28, 25 and 33 °C), which were ordered randomly in the experimental protocol to avoid acclimation bias. Experiments were repeated for a winter and summer season. In general, Amethyst Sunbird subpopulations from Underberg and Howick showed higher post-acclimation resting metabolic rates per temperature in winter than in summer trials. Underberg and Howick subpopulations respectively showed a significant difference between summer and winter V̇O2 at 5 and 10 °C. Thermal neutral zones of all of the subpopulations of sunbirds shifted between winter and summer. Post-acclimation basal metabolic rate of sunbirds decreased significantly by 38.8% from winter to summer for the Underberg subpopulation, increased by 44.8% for the Howick subpopulation and did not change significantly for the Oribi Gorge subpopulation (5.8% decrease). [Copyright &y& Elsevier]

Abstract: Metabolic rates and thermal tolerances of three species of mobile symbiotic molluscs (two provannid gastropods Alviniconcha sp. and Ifremeria nautilei; and the mussel Bathymodiolus brevior) from Lau Basin hydrothermal vents were measured. Thermal tolerances of the two gastropods were similar and well in excess of temperatures observed in situ, although Alviniconcha sp. appeared to have slightly higher tolerances. B. brevior had lower thermal limits that could exclude it from central areas of active venting. High-pressure respirometry experiments revealed that Alviniconcha sp. has very high potential growth rates; its uptake of carbon for its endosymbionts being among the highest recorded. Uptake rates of metabolites in I. nautilei and B. brevior were an order of magnitude lower than those observed in Alviniconcha sp. Taken together, these thermal tolerances and metabolite uptake rates help to explain the zonation patterns seen in situ, where Alviniconcha sp. is found closest to the source of vent fluid, followed by I. nautilei, and then B. brevior. [Copyright &y& Elsevier]

Abstract: Sodium sulfate is a ubiquitous salt that reaches toxic concentrations due to mining and other industrial activities, yet is currently unregulated at the Federal level in the United States. Previous studies have documented reduced growth of clams downstream of sulfate-dominated effluents, altered bioenergetics in filter-feeding invertebrates, and interactions between sulfate and other toxicants. Therefore, the purpose of this study was to determine if sodium sulfate affects the bioenergetics of the filter-feeding, freshwater bivalve, Corbicula fluminea, and the mechanism by which the effects are elicited. In addition to measuring effects on feeding, respiration and growth rates, I evaluated the relative sensitivity of a green algae consumed by clams to determine if top-down or bottom-up effects might be exhibited under field conditions. This study demonstrated that sodium sulfate had no effect on basal metabolic rates, but significantly reduced the feeding, post-feeding metabolic, and growth rates of C. fluminea. The proposed mechanism for these impacts is that filtering rates are reduced upon exposure, resulting in reduced food consumption and therefore, preventing increased metabolic rates normally associated with post-feeding specific dynamic action (SDA). In the field, these effects may cause changes in whole stream respiration rates and organic matter dynamics, as well as alter uptake rates of other food-associated contaminants like selenium, the toxicity of which is known to be antagonized by sulfate, in filter-feeding bivalves. [Copyright &y& Elsevier]

Abstract: Adult specimens of two species of clams, Ruditapes decussatus and Venerupis pullastra, were starved for 84 days to determine the effect of starvation on their metabolism. The energy cost of metabolism in starvation was assessed using the oxygen consumption rates (respiration rates) of the clams and assessing the type of fuel used to provide this energy by analyzing their biochemical composition. Respiration rates decreased in both species after 15 days of starvation and remained at basal levels throughout the rest of the experimental period. Both during the first period and also after the metabolism had slowed down, the amount of energy consumed in respiration was higher in V. pullastra than in R. decussatus. The energy needed to maintain vital functions in both species is obtained from catabolism of body components, with a reduction in dry mass of the specimens, and consequently their energy content, in both species. This reduction was greater in V. pullastra given that energy demand is higher in this species. In both species carbohydrates made the largest contributions to energy output, followed by lipids in males and proteins in females. However, the energy contribution of each biochemical component differs according to species: R. decussatus obtains its energy from the catabolism of carbohydrates and proteins in equal proportion, while V. pullastra obtains it from proteins and lipids. In both species, albeit to a greater extent in R. decussatus, we observed that female specimens conserved their lipids until the later stages of the period of starvation (day 70), after which they started to metabolise their lipid components more intensely. The interspecific differences are interpreted in relation to the different habitat occupied by the two species. [Copyright &y& Elsevier]

Energy metabolism in early life stages of the shrimp Farfantepenaeus paulensis subjected to temperature reduction (26 and 20 °C) was determined using the activities of citrate synthase (CS) and pyruvate kinase (PK). At both temperatures, weight-specific activity of CS decreased throughout the ontogenetic development from protozoea II (PZ II) to postlarva XII–XIV (PL XII–XIV). PK activity reached a pronounced peak in PL V–VI, followed by a further decrease in PL XII–XIV. Temperature reduction produced variation in oxygen consumption rates (QO2), ammonia–N excretion and in enzyme activities. Ammonia–N excretion was higher at 20 °C in mysis III (M III), PL V–VI and PL XII–XIV, resulting in substantially lower O:N ratios in these stages. QO2 was increased in protozoea II (PZ II) and mysis I (M I) at 26 °C, while no difference in QO2 was detected in the subsequent stages at either temperature. This fact coincided with higher CS and PK activities in M III, PL V–VI and PL XII–XIV at 20 °C compared with 26 °C. Regressions between individual enzyme activities and dry weight exhibited slope values of 0.85–0.92 for CS and 1.1–1.2 for PK and temperature reduction was reflected by higher slope values at 20 than at 26 °C for both enzymes. Weight-specific CS activity was positively correlated with QO2 at 20 and 26 °C, and may thus be used as an indicator of aerobic metabolic rate throughout the early stages of F. paulensis. The variation in enzyme activities is discussed in relation to possible metabolic adaptations during specific ontogenetic events of the F. paulensis life cycle. Here, the catalytic efficiency of energy-metabolism enzymes was reflected in ontogenetic shifts in behaviour such as larval settlement and the adoption of a benthic existence in early postlarvae. In most cases, enhanced enzyme activities appeared to counteract negative effects of reduced temperature. [Copyright &y& Elsevier]

Proteinase (endopeptidase), trypsin and chymotrypsin activities, RNA, and DNA contents were examined throughout the ontogenetic development of cultured Litopenaeus schmitti. Whole individuals from larval and postlarval stages, and adult hepatopancreas were homogenized and assayed for quantification of enzyme activity. Proteinase activity of different life stages was characterized by substrate-SDS-PAGE. Specific inhibitors for trypsin (TLCK) and serine proteinases (PMSF) were used to identify activity zones of these enzymes in gels. Nucleic acids were also quantified in larval and postlarval stages. Protein-specific activity of total proteinases and trypsin presented higher values in nauplius IV (N IV), protozoea I (PZ I), and PZ III, compared to the remaining stages, while chymotrypsin activity peaked in N IV and PZ III. Enzyme activity was lower in egg, early nauplius, mysis, and postlarval stages. Different proteinase patterns were observed in SDS-PAGE during ontogenetic development. Active bands of 15.5, 16.0, 19.9, 21.8, 24.0, 27.9, 30.3, 33.5, 35.5, 38.2, and 48.1 kDa were detected in the adult hepatopancreas. In the course of development, proteolytic activity was detected in N IV, and intense bands of 17.3, 19.9, and 20.9 kDa were found up to mysis (M III). A band at 38.2 kDa was present between N IV and M I, and between PL II and PL IV. Most bands were serine proteinases, and only two bands in adult (15.5 and 15.9 kDa) were inhibited by TLCK. Both RNA and DNA contents (μg mg−1 of fresh weight) reduced with development from egg to PZ III, increasing afterwards until PL IV. RNA/DNA ratios increased from egg, reaching a peak in PZ I, and decreased in the following stages until a minimum was reached in M II. A secondary peak was observed in PL III followed by reduction in PL IV. The variation in enzyme activity indicates different strategies of energy use throughout development. Higher enzyme activity combined with increased RNA/DNA in protozoeal stages denotes intense food energy use and accumulation into growth. The shift in energy strategy during the ontogeny of L. schmitti is accompanied by variation in proteinase characteristics as observed in other penaeid species. [Copyright &y& Elsevier]

Climate change is leading to alterations in salinity and carbonate chemistry in arctic/sub-arctic marine ecosystems. We examined three nominal populations of the circumpolar arctic/subarctic amphipod, Gammarus setosus , along a salinity gradient in the Kongsfjorden-Krossfjorden area of Svalbard. Field and laboratory experiments assessed physiological (haemolymph osmolality and gill Na+/K+-ATPase activity, NKA) and energetic responses (metabolic rates, MO 2 , and Cellular Energy Allocation, CEA). In the field, all populations had similar osmregulatory capacities and MO 2 , but lower-salinity populations had lower CEA. Reduced salinity (S = 23) and elevated p CO 2 (~1000 μatm) in the laboratory for one month increased gill NKA activities and reduced CEA in all populations, but increased MO 2 in the higher-salinity population. Elevated p CO 2 did not interact with salinity and had no effect on NKA activities or CEA, but reduced MO 2 in all populations. Reduced CEA in lower-rather than higher-salinity populations may have longer term effects on other energy demanding processes (growth and reproduction). • Climate change is leading to changes in salinity and p CO 2 in arctic/sub-arctic coastal ecosystems. • We examined Gammarus setosus at 3 sites along a salinity gradient in the field and laboratory. • Reduced salinity had more of an effect than elevated p CO 2 by reducing energy budgets. • Lower salinities increased ion transporting capacities in the laboratory but not in the field. • G. setosus at lower salinity sites have lower energy budgets suggesting impacts on performance. [ABSTRACT FROM AUTHOR]

• Benthic foraminiferal turnover across the LLTM is documented for the first time. • Deep-sea environmental perturbation lasted longer than the LLTM CIE. • Assemblage shifts suggest changes in organic matter type reaching the seafloor. • CFARs and δ18O values show correlation, suggesting a link with LLTM temperatures. • A similar paleoecological response was recorded across the MECO at the same site. [ABSTRACT FROM AUTHOR]

• Metabolic rates estimated from flow-through systems must be corrected for hydraulic lag. • The most accurate correction equation depends on the variability of the metabolic rates. • For data with real variability, corrected metabolic rates based on mean concentrations may be more accurate than those based on instantaneous values. • For typical commercial systems, minutely corrected metabolic rates should be computed and then averaged over longer periods. • For data collected at longer time periods, the accuracy of the corrected metabolic rates will be reduced. • Similar issues apply to TAN, CO 2 , SS, as well performance data from unit processes. Oxygen consumption and other metabolic rates for commercial systems are typically measured under flow-through conditions and therefore are biased because of hydraulic lag. To evaluate potential correction approaches, three representative (SINE, STEP, MULTI-STEP) daily metabolic responses (R t a) were developed. Using the values of R t a , the resulting concentration of dissolved oxygen (C t i) on a minutely basis over the day was estimated from either a hydraulic mixing model or mass balance equations. Six approaches (STEADY, FRY, NORTHBY, NIIMI, SPLINE, and POLY) were used to estimate the metabolic oxygen consumption rate (R t) for the 20-, 40-, and 60-minute periods. Three analytical approaches were tested (MEAN, POINT, and DETAILED). Based on all three test metabolic rates, the combination of the DETAILED analytical approach and the SPLINE correction was the most accurate. The DETAILED approach is based on estimation of the minutely oxygen consumption and computation of the average rate over a specific time period. The combination of DETAILED and NIIMI was more accurate for STEP and MULTI-STEP but was very inaccurate for the SINE response. It is not surprising that NIIMI is an excellent correction for STEP and MULTI-STEP as the derivation of this equation was based on a step change in metabolic rate. STEADY was the least accuracy for all metabolic response. For SINE, all of the equations can be used to estimate the daily average value ( R ¯ d a i l y ). For STEP and MULTI-STEP, STEADY is less accurate. STEADY under-estimated the upper and lower peaking factors, but the other correction equations were very accurate. This same lag response can also bias other metabolic rates (carbon dioxide, ammonia, solids) and the computation of performance and efficiencies of unit processes such as biofilters and solids removal processes. The correction of unit process performance metrics may be further complicated by rapid changes in influent concentrations that were not considered in these correction approaches and the kinetic response of the process to changes in substrate concentrations. [ABSTRACT FROM AUTHOR]