Mass-specific Oxygen Consumption Research Articles

Temperature effects on oxygen consumption and breathing pattern in juvenile and adult Chelonoidis carbonarius (Spix, 1824)

The effects of temperature on breathing pattern and oxygen consumption are being investigated in juvenile tortoises and compared to adults, in order to understand physiological adjustments of the respiratory system as related to body size, especially regarding the energetic expenditure associated with growth. We analyzed the breathing pattern and oxygen consumption of juvenile and adult red-footed tortoises (Chelonoidis carbonarius, Cryptodira: Testudinidae). The animals (N = 9; body mass ranging from 0.03 Kg to 2.5 Kg) were exposed to normoxic-normocarbic conditions using open respirometry in order to determine the breathing pattern and oxygen consumption in three different temperatures (15, 25, 35 °C). The obtained results showed intermittent breathing pattern in all tested temperatures in juveniles and adults. Tidal volume was not affected by changes in temperature, while breathing frequency increased significantly with increasing temperature, leading to a significant increment in minute ventilation between 15 and 35 °C. Mass specific oxygen consumption increased significantly with temperature and juveniles showed greater values when compared to adults. The alterations in the ventilatory response to temperature changes occurred in order to maintain the oxygen supply with increased metabolic activity. The differences between juveniles and adults in breathing frequency lead to juveniles needing a lower ventilation rate to perform gas exchange while extracting more oxygen. While these differences might be attributed to a greater metabolic expenditure during development, scaling effects on respiratory variables might be the main contributors to the found differences.

Local-scale thermal history influences metabolic response of marine invertebrates to warming

As climate change continues, anticipating species’ responses to rising temperatures requires an understanding of the drivers of thermal sensitivity, which itself may vary over space and time. We measured metabolic rates of three representative marine invertebrate species (hermit crabs Pagurus hirsutiusculus, periwinkle snails Littorina sitkana, and mussels Mytilus trossulus) and evaluated the relationship between thermal sensitivity (Q10) and thermal history. We tested the hypothesis that thermal history drives thermal sensitivity and quantified how this relationship differs over time (short-term to seasonal time scales) and between species. Organisms were collected from tide pools in Sitka, Alaska where we also recorded temperatures to characterize thermal history prior to metabolic rate assays. Using respirometry, we estimated mass-specific oxygen consumption (MO2) at ambient and increased temperatures for one individual per species per tide pool across three seasons. We evaluated relationships between thermal sensitivity and pool temperatures for time periods ranging from 1 day to 1 month prior to collection. For all species, thermal sensitivity was related to thermal history for the shorter time periods (1 day to 1 week). However, the direction of the relationships and most important thermal parameters (i.e., maximum, mean, or range) differed between species and seasons. We found that on average, P. hirsutiusculus and L. sitkana were more thermally sensitive than M. trossulus. These findings show that variability in thermal history over small spatial scales influences individuals’ metabolic response to warming and may be indicative of these species’ ability to acclimate to future climate change.

High resolution acoustic telemetry reveals swim speeds and inferred field metabolic rates in juvenile white sharks (Carcharodon carcharias).

White sharks (Carcharodon carcharias) are the largest shark species to display regional endothermy. This capability likely facilitates exploitation of resources beyond thermal tolerance thresholds of potential sympatric competitors as well as sustained elevated swim speeds, but results in increased metabolic costs of adults, which has been documented in different studies. Little, however, is known of the metabolic requirements in free-swimming juveniles of the species, due to their large size at birth and challenges in measuring their oxygen consumption rates in captivity. We used trilateration of positional data from high resolution acoustic-telemetry to derive swim speeds from speed-over-ground calculations for eighteen free-swimming individual juvenile white sharks, and subsequently estimate associated mass-specific oxygen consumption rates as a proxy for field routine metabolic rates. Resulting estimates of mass-specific field routine metabolic rates (368 mg O2 kg−1 h−1 ± 27 mg O2 kg−1 h−1 [mean ± S.D.]) are markedly lower than those reported in sub-adult and adult white sharks by previous studies. We argue that median cruising speeds while aggregating at nearshore nursery habitats (0.6 m s-1 [mean ± S.E = 0.59 ± 0.001], 0.3 TL s-1) are likely a feature of behavioral strategies designed to optimize bioenergetic efficiency, by modulating activity rates in response to environmental temperature profiles to buffer heat loss and maintain homeostasis. Such behavioral strategies more closely resemble those exhibited in ectotherm sharks, than mature conspecifics.

Thermal tolerance and routine oxygen consumption of convict cichlid, Archocentrus nigrofasciatus, acclimated to constant temperatures (20°C and 30°C) and a daily temperature cycle (20°C → 30°C).

Organismal temperature tolerance and metabolic responses are correlated to recent thermal history, but responses to thermal variability are less frequently assessed. There is great interest in whether organisms that experience greater thermal variability can gain metabolic or tolerance advantages through phenotypic plasticity. We compared thermal tolerance and routine aerobic metabolism of Convict cichlid acclimated for 2weeks to constant 20°C, constant 30°C, or a daily cycle of 20 → 30°C (1.7°C/h). Acute routine mass-specific oxygen consumption ([Formula: see text]O2) and critical thermal maxima/minima (CTMax/CTMin) were compared between groups, with cycle-acclimated fish sampled from the daily minimum (20°C, 0900h) and maximum (30°C, 1600h). Cycle-acclimated fish demonstrated statistically similar CTMax at the daily minimum and maximum (39.0°C, 38.6°C) but distinct CTMin values, with CTMin 2.4°C higher for fish sampled from the daily 30°C maximum (14.8°C) compared to the daily 20°C minimum (12.4°C). Measured acutely at 30°C, [Formula: see text]O2 decreased with increasing acclimation temperature; 20°C acclimated fish had an 85% higher average [Formula: see text]O2 than 30°C acclimated fish. Similarly, acute [Formula: see text]O2 at 20°C was 139% higher in 20°C acclimated fish compared to 30°C acclimated fish. Chronic [Formula: see text]O2 was measured in separate fish continually across the 20 → 30°C daily cycle for all 3 acclimation groups. Chronic [Formula: see text]O2 responses were very similar between groups between average individual hourly values, as temperatures increased or decreased (1.7°C/h). Acute [Formula: see text]O2 and thermal tolerance responses highlight "classic" trends, but dynamic, chronic trials suggest acclimation history has little effect on the relative change in oxygen consumption during a thermal cycle. Our results strongly suggest that the minimum and maximum temperatures experienced more strongly influence fish physiology, rather than the thermal cycle itself. This research highlights the importance of collecting data in both cycling and static (constant) thermal conditions, and further research should seek to understand whether ectotherm metabolism does respond uniquely to fluctuating temperatures.

Variation in metabolic rate and a test of differential sensitivity to temperature in populations of woolly sculpin (Clinocottus analis)

Variation in water temperature can have important effects on the energetics underlying metabolism, growth, and reproduction of many organisms. In order to anticipate how a species' allocation of energy may change in a warming ocean, we need to know the degree to which processes such as metabolic rate change with temperature (i.e., the thermal sensitivity of metabolism, Q10). In the context of long-term climate change, it will also be helpful to know whether local populations that experience different thermal regimes exhibit differences in thermal sensitivity. If so, it would indicate that thermal sensitivities of populations may adjust via acclimation or adaptation. We measured metabolic rates of Woolly Sculpin collected from two distant populations (Santa Cruz (SC) and Los Angeles (LA) counties, California, USA) and housed in a common environment. Using respirometry, we estimated resting mass-specific oxygen consumption (MO2) and calculated metabolic rates (MR) at temperatures of 12 °C, 16 °C, and 20 °C for 59 fish. The Q10 value across this range of temperatures was 2.92. Populations did not differ with respect to overall MO2, nor did they vary in their degree of thermal sensitivity. However, the LA population had greater variation in MO2 among individuals when compared to the SC population. Larger variation in overall MO2 among individuals within specific populations may reflect greater genetic diversity, and this may buffer some populations against the effect of future increases in water temperature.

Temperature-Modulated Expression of Allometric Respiration Strategies Supports a Metabolic Scaling Rule

A model based on the mass-specific oxygen consumption rate of the tolerant polychaete, Capitella telata, related meaningfully to a novel metabolic scaling rule as applied to the infaunal size spectrum. Depending on temperature, C. telata expressed divergent oxyregulating or oxyconforming strategies relative to oxygen availability. A non-linear response surface fitted to the allometric exponents of a family of VO2 curves for 12 treatment combinations of DO saturation and temperature was used to project oxygen consumption rates across the infaunal size spectrum. Plasticity in respiration strategies was evident, based on four simulated dynamic 32 d oxygen-temperature exposure scenarios and on simulated static oxygen-temperature exposures. The oxyconforming strategy of C. telata expressed under hypoxia near the upper thermal limit agreed with a hypothesized allometric scaling rule based on metabolic ecology. Conversely, an oxyregulating respiration strategy was expressed at cooler temperatures under low oxygen concentration, except organisms hyper-regulated relative to normoxic conditions. At warm temperatures, small organisms exhibited relatively greater metabolic depression than large organisms; whereas at cool temperatures, small organisms hyper-regulated relatively more than large organisms. Dichotomous shifts in respiration strategies likely reflect a breakdown in the functioning of special adaptations, and reliance on alternative coping mechanisms. Divergent temperature-dependent respiration strategies illustrate how responses to multiple stressors can be synergistic. Moreover, results imply that population responses to hypoxia may differ, depending on prevailing temperature regimes.

Do Alluvial Sand Dunes Create Energetic Refugia for Benthic Fishes? An Experimental Test with the Endangered Pallid Sturgeon

AbstractRiver modifications have altered critical habitats for fishes at a variety of spatial scales and caused global declines of many fluvial species. At small spatial scales (<1 m2), alluvial sand dunes, a ubiquitous habitat in highly modified rivers, are thought to provide energetic relief for benthic fishes in energetically costly riverine landscapes created by water flow. However, use of alluvial dune habitat is not well understood, and it is unclear whether dunes provide refuge that effectively reduces energetic costs. We designed a scale‐relevant experiment to examine the energetic responses associated with sand dune habitat in rivers. We tested whether the US federally endangered pallid sturgeon (Scaphirhynchus albus), a benthic fish commonly associated with sand dunes, experienced reduced energetic costs with different configurations of simulated sand dune habitat. We quantified mass specific oxygen consumption (MO2; mg O2 kg−1 h−1) using intermittent flow‐through respirometry for age‐0 sturgeon (140–170 mm) in front of a sand dune, behind a sand dune and in the absence of a sand dune at two velocities (25 and 50 cm s−1) commonly observed in field studies of sturgeon habitat use. Sturgeon displayed distinct station holding behaviours for each habitat configuration. Dune location did not affect energy expenditure, but sturgeon MO2 was on average 16–20% higher in the absence of a sand dune depending on dune configuration. MO2 was on average 14% higher at 50 cm s−1 compared with 25 cm s−1. Our results provide a potential mechanism for over two decades of research on why sturgeon and other benthic fishes exhibit selection for sand dune habitat in large rivers. Fishes that select main channel habitats may depend on energetic relief provided by sand dunes, especially when other forms of structure are not available. For this reason, alluvial sand dune habitat may be important to the persistence of benthic fishes in high flow environments. Copyright © 2017 John Wiley & Sons, Ltd.

A disparity between locomotor economy and territory-holding ability in male house mice.

Both economical locomotion and physical fighting are important performance traits to many species because of their direct influence on components of Darwinian fitness. Locomotion represents a substantial portion of the total daily energy budget of many animals. Fighting performance often determines individual reproductive fitness through the means of resource control, social dominance and access to mates. However, phenotypic traits that improve either locomotor economy or fighting ability may diminish performance in the other. Here, we tested for a predicted disparity between locomotor economy and competitive ability in wild-derived house mice (Mus musculus). We used 8week social competition trials in semi-natural enclosures to directly measure male competitive ability through territorial control and female occupancy within territories. We also measured oxygen consumption during locomotion for each mouse using running trials in an enclosed treadmill and open-flow respirometry. Our results show that territory-holding males have higher absolute and mass-specific oxygen consumption when running (i.e. reduced locomotor economy) compared with males that do not control territories. This relationship was present both before and after 8week competition trials in semi-natural enclosures. This disparity between physical competitive ability and economical locomotion may impose viability costs on males in species for which competition over mates is common and may constrain the evolution of behavioral and phenotypic diversity, particularly in natural settings with environmental and resource variability.

Retraction: Tusk shells in trouble? Physiology and behavior in response to changing temperature in a scaphopod (Mollusca: Scaphopoda: Dentaliida). Sigwart et al. (2016)

Invertebrate BiologyVolume 136, Issue 1 p. 113-113 RetractionFree Access Retraction: Tusk shells in trouble? Physiology and behavior in response to changing temperature in a scaphopod (Mollusca: Scaphopoda: Dentaliida). Sigwart et al. (2016) This article retracts the following: Retracted: Tusk shells in trouble? Physiology and behavior in response to changing temperature in a scaphopod (Mollusca: Scaphopoda: Dentaliida) Julia D. Sigwart, Nicholas Carey, Lauren H. Sumner-Rooney, Volume 135Issue 3Invertebrate Biology pages: 191-199 First Published online: June 3, 2016 First published: 12 December 2016 https://doi.org/10.1111/ivb.12157AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract The above article, published online on 3 June 2016 in Wiley Online Library, is retracted voluntarily by agreement among the authors, the Editor-in-Chief (Michael Hart), and the Editor (Amy Moran). The study focused on behavior and mass-specific oxygen consumption rates in specimens of the northeastern Pacific scaphopod species Rhabdus rectius (Carpenter 1864) collected from a wild study population in September 2013. The authors used a method that we assumed to be reliable, based on the literature for similar scaphopod species, to distinguish males from females by gonad color (white or slightly pink ovaries; yellow testes) visible through the thin shell. After the article was published, the corresponding author notified the editors of new observations by the authors indicating that our published identifications of sex were in error. Histological sections of gonads from a small number of individuals of R. rectius, sampled from the same wild study population, revealed that, contrary to expectations, yellow individuals were female, and white individuals were male. These results contradict the identifications of sex made in the published article. Uncertainty in the sex identifications affects some quantitative analyses in the published article that were based in part on sex differences. The article has been retracted only for that reason. The other data reported in the published article (burying times; body masses; individual oxygen consumption rates) are not directly affected by the error in sex identification. The authors apologize for any confusion caused. We are grateful to the editors, Amy Moran and Michael Hart, for their helpful support in resolving this matter and correcting the scientific record. Reference Sigwart JD, Carey N, & Sumner-Rooney LH 2016. Tusk shells in trouble? Physiology and behavior in response to changing temperature in a scaphopod (Mollusca: Scaphopoda: Dentaliida). Invertebr. Biol. 135: 191–199 doi:10.1111/ivb.12127. Volume136, Issue1March 2017Pages 113-113 RelatedInformation

Hypoxia tolerance decreases with body size in red drum Sciaenops ocellatus.

Mass-specific oxygen consumption rate, i.e. standard metabolic rate (Rs ) and critical oxygen tension (Pcrit ) of red drum Sciaenops ocellatus were measured and scaled over a 2500-fold range in mass (MF ; 0·26-686 g). Rs conformed to well established models (Rs = 3·73·91 MF (-0·21) ; r(2) = 0·86) while Pcrit increased over the size range (Pcrit = 3·15 log10 MF + 16·19; r(2) = 0·44). This relationship may be ecologically advantageous as it would allow smaller S. ocellatus to better utilize hypoxic zones as habitat and refuge from predators.

Comparison of swimming capacity and energetics of migratory European eel (Anguilla anguilla) and New Zealand short-finned eel (A. australis).

The spawning migration of the European eel (Anguilla anguilla) can cover more than 6000 km, while that of the New Zealand short-finned eel (A. australis) is assumed to be approximately 3000 km. Since these species are expected to show adaptive traits to such an important lifetime event, we hypothesized differences in swimming capacity and energetics as a response to this adaptation. In an experimental swimming respirometer set-up, critical swimming speed (Ucrit), optimal swimming speed (Uopt), mass specific oxygen consumption rate (ṀO2), standard metabolic rate (SMR), active metabolic rate at Ucrit (AMRcrit) and at Uopt (AMRopt), the minimum cost of transport at Uopt (COTmin), and the scope for activity, were assessed and compared between the species. With a similar body length and mass, European eels showed ca. 25% higher values for both Ucrit and Uopt, and 23% lower values for COTmin, compared to New Zealand short-finned eels. However, SMR, AMRcrit, AMRopt, and scope for activity did not differ between the species, indicating very similar swimming physiology traits. This study discusses physiological aspects of long distance migration and provides recommendations for (a) swimming respirometry in anguilliform fish, and (b) telemetry research using externally attached pop-up tags.

Bottlenose dolphins modify behavior to reduce metabolic effect of tag attachment.

Attaching bio-telemetry or -logging devices ('tags') to marine animals for research and monitoring adds drag to streamlined bodies, thus affecting posture, swimming gaits and energy balance. These costs have never been measured in free-swimming cetaceans. To examine the effect of drag from a tag on metabolic rate, cost of transport and swimming behavior, four captive male dolphins (Tursiops truncatus) were trained to swim a set course, either non-tagged (n=7) or fitted with a tag (DTAG2; n=12), and surface exclusively in a flow-through respirometer in which oxygen consumption VO₂ and carbon dioxide production (VO₂; ml kg(-1) min(-1)) rates were measured and respiratory exchange ratio (VO₂/resting VO₂) was calculated. Tags did not significantly affect individual mass-specific oxygen consumption, physical activity ratios (exercise /resting ), total or net cost of transport (COT; J m(-1) kg(-1)) or locomotor costs during swimming or two-minute recovery phases. However, individuals swam significantly slower when tagged (by ~11%; mean ± s.d., 3.31±0.35 m s(-1)) than when non-tagged (3.73±0.41 m s(-1)). A combined theoretical and computational fluid dynamics model estimating drag forces and power exertion during swimming suggests that drag loading and energy consumption are reduced at lower swimming speeds. Bottlenose dolphins in the specific swimming task in this experiment slowed to the point where the tag yielded no increases in drag or power, while showing no difference in metabolic parameters when instrumented with a DTAG2. These results, and our observations, suggest that animals modify their behavior to maintain metabolic output and energy expenditure when faced with tag-induced drag.

Renal, metabolic and hematological effects of trans-retinoic acid during critical developmental windows in the embryonic chicken

All-trans-retinoic acid (tRA), an active metabolite of vitamin A, directly influences the developing kidney, and is a major regulatory signal during vertebrate organogenesis. The aim of the current study was to specifically target potential critical windows in renal development, and assess altered renal function through disruptions in embryonic fluid compartments. In addition, the effect of exogenous tRA administration on embryonic growth and metabolism was determined. Embryos were exposed to 0.1 or 0.3 mg tRA on embryonic day 8. Morphological and physiological measurements were made on days 12, 14, 16 and 18. Embryo wet mass on day 18 was reduced by 23 % (0.1 mg tRA) and 44 % (0.3 mg tRA). tRA exposure elevated mass-specific oxygen consumption in embryos exposed to 0.1 mg (21.2 ± 0.3 μL(-1) g(-1) min(-1)) and 0.3 mg (23.4 ± 0.4 μL(-1) g(-1) min(-1)) when compared to sham (18.9 ± 0.6 μL(-1) g(-1) min(-1)) on day 14, but not subsequent incubation days. Osmolality of blood plasma was transiently lowered in embryos exposed to 0.3 mg tRA between days 14 and 16. Allantoic fluid osmolality was significantly elevated by tRA to ~220 mmol L(-1) from days 16 to 18 compared to controls. Blood plasma [Na(+)] was reduced by ~17 % over the same period, while allantoic fluid [Na(+)] was elevated in tRA-treated embryos compared to control embryos. Collectively, our data indicates that exogenous administration of tRA produces significant alterations to the developmental trajectory of the developing embryonic chicken.

Respiration rates of tropical Atlantic copepods in relation to the oxygen minimum zone

Zooplankton respiration plays an important role in the carbon cycling of pelagic ecosystems. The rate of oxygen consumption in zooplankton is affected by the physical environment, vertical distribution range and species-specific behavior. Especially in tropical oceans, oxygen minimum zones (OMZs) may influence zooplankton metabolic processes and vertical distribution and thus structure zooplankton communities. Here we present respiration rates of tropical Atlantic copepods in relation to environmental factors, especially O2 concentration, and species-specific characteristics. Copepods were sampled during two research stays on the Cape Verde Island São Vicente in March/April and May/June 2010. Minimum O2 concentrations of 51μmolkg−1 (pO2 of 4.25kPa) at 400m depth were recorded within the OMZ. Respiration rates of epi- and mesopelagic calanoid copepods were measured by optode respirometry at three different ambient temperatures (13, 18, and 23°C) to establish the effect of temperature on metabolic rates. Mass-specific oxygen consumption ranged from 27μmolO2gDM−1h−1 in copepodids C5 of Lophothrix sp. at 13°C to 774μmolO2gDM−1h−1 in Pleuromamma xiphias copepodids C5 at 18°C and was mainly controlled by body mass and temperature. Mass-specific respiration rates were highest in surface-dwelling organisms and decreased with increasing depth. To allow for a comparison of shallow and deep-living copepods, respiration rates were standardized to a common temperature of 18°C and a mean body dry mass of 0.5mg, applying a Q10 of 2.0 and a body mass exponent of −0.56. Temperature- and body mass-corrected respiration rates did not decrease with increasing depth indicating that neither depth of occurrence, nor current hypoxic conditions within the OMZ had a fundamental, persistent effect on zooplankton respiration.

Metabolic responses of the South American ornate horned frog (Ceratophrys ornata) to estivation

We examined the metabolic responses of the South American frog, Ceratophrys ornata, to laboratory-induced estivation. Whole-animal and mass-specific oxygen consumption rates (VO(2)) did not change during fasting or 56days of estivation, despite observing significant decreases in body mass. The maintenance of mass-specific metabolic rate at routine levels during estivation suggests that metabolic rate suppression is not a major response to estivation in this species. There was a significant decline in liver glycogen and a loss of adipose tissue mass during estivation, suggesting that both carbohydrate and lipid pathways are used to fuel metabolism during estivation. The activity of pyruvate dehydrogenase, an important regulator of carbohydrate oxidation, and carnitine palmitoyltransferase and 3-hydroxyacyl-CoA dehydrogenase, regulators of lipid oxidation, showed no significant change in activity in liver, heart, and muscle between estivating and active frogs. There was an increase in plasma osmolality, which is characteristic of estivating animals. Overall, our metabolic analysis of estivation in C. ornata indicates that this species does not employ a dramatic suppression metabolic rate to survive dehydration stress and that both endogenous carbohydrates and lipids are used as metabolic fuels.

Cardiac and Metabolic Physiology of Early Larval Zebrafish (Danio rerio) Reflects Parental Swimming Stamina

Swimming stamina in adult fish is heritable, it is unknown if inherited traits that support enhanced swimming stamina in offspring appear only in juveniles and/or adults, or if these traits actually appear earlier in the morphologically quite different larvae. To answer this question, mature adult zebrafish (Danio rerio) were subjected to a swimming performance test that allowed separation into low swimming stamina or high swimming stamina groups. Adults were then bred within their own performance groups. Larval offspring from each of the two groups, designated high (LHSD) and low stamina-derived larvae (LLSD), were then reared at 27°C in aerated water (21% O2). Routine (fH,r) and active (fH,a) heart rate, and routine and active mass-specific oxygen consumption were recorded from 5 days post fertilization (dpf) through 21 dpf, and gross cost of transport and factorial aerobic metabolic scope were derived from measurements. Heart rate generally ranged between 150 and 225 bpm in both LHSD and LLSD populations. However, significant (P < 0.05) differences existed between the LLSD and LHSD populations at 5 and 14 dpf in fH,r and at days 10 and 15 dpf in fH,a. was 0.04–0.32 μmol mg−1 h−1, while was 0.2–1.2 μmol mg−1 h−1. Significant (P < 0.05) differences between the LLSD and LHSD populations in occurred at 7, 10, and 21 dpf and in at 7 dpf. Gross cost of transport was ∼6–10 μmol O2·μg−1 m−1 at 5 dpf, peaking at 14–19 μmol O2 μg−1 m−1 at 7–10 dpf, before falling again to 5–6 μmol O2 μg−1 m−1 at 21 dpf, with gross cost of transport significantly higher in the LLSD population at 7 dpf. Collectively, these data indicate that inherited physiological differences known to contribute to enhanced stamina in adult parents also appear in their larval offspring well before attainment of juvenile or adult features.

Metabolism and chemical composition of phyllosoma larvae, with special reference to the tropical rock lobster Panulirus ornatus (Decapoda; Palinuridae)

Rates of oxygen consumption and ammonia excretion and chemical composition (water, ash and CN composition) were determined throughout larval development, from Stages I–IX, of Panulirus ornatus phyllosoma larvae raised in the laboratory. Dry mass (DM) specific oxygen consumption rates varied from 1.4 to 3.3 μl O 2 (DM) −1 h −1, showing a pattern of developmental decline. In contrast, specific ammonia excretion rates fluctuated irregularly from 0.02 to 0.067 μg NH 4–N (DM) −1 h −1, yielding oxygen consumption to ammonia excretion ratios (O:N atomic ratio) as wide as 51–180. With progressive development, ash decreased from 34% to 17% of DM while C composition increased from 33% to 41% of DM. No consistent changing pattern with development was seen for water contents (74–83% of WM), N composition (6.9–9.5% of DM) and C:N ratios (4.0–5.1). Supplemental data of both specific oxygen consumption and ammonia excretion rates of laboratory-raised Stage III P. homarus and wild Parribacus antarcticus phyllosoma (stage unknown) of this study and literature data on phyllosomas of other lobster species by previous workers were shown to be comparable to those of P. ornatus phyllosomas when the differences in DM and temperature were taken into account. No appreciable differences due to the origin of the specimens, whether wild or laboratory-raised, were evident. Comparison of the present results with those of stomatopod larvae and holoplanktonic crustaceans in the same tropical marine habitats revealed that phyllosoma larvae are characterized by somewhat lower DM specific oxygen consumption rates and N composition. The study revealed markedly reduced ammonia excretion rates in phyllosomas, suggesting reduced swimming activity and preferential utilization of dietary protein to somatic growth rather than metabolism.

Oxygen consumption of the earthworm species Dendrobaena mrazeki

Dendrobaena mrazeki is an endemic earthworm species inhabiting dry habitats such as pine and thermophilous oak forests in Central Europe. Metabolically, D. mrazeki showed some features typical for endogeic species and some of epigeic ones. In comparison with the related Dendrobaena octaedra, D. mrazeki was a larger earthworm with fresh body mass of adult and subadult individuals of W = 0.59 ± 0.05 g. Its body mass-specific oxygen consumption ( M/ W = 48 ± 5 μl O 2 g −1 h −1, at 15 °C) was the lowest of all earthworms studied ( Aporrectodea caliginosa, Aporrectodea rosea, D. octaedra, Lumbricus castaneus, Lumbricus rubellus and Octolasion lacteum), being strongly dependent on W ( b from the equation M/ W = aW b about −0.8). D. mrazeki had low relative water content (77.4% of fresh body mass) and small relative amount of dry weight of the intestinal content (20.1% of dry body mass), which is similar to the epigeic D. octaedra. The respiration rate of D. mrazeki remained the lowest even after recalculating M/ W to respiration rate per dry mass or per dry mass without the intestine content to correct for the differences among species in body water content and gut content.

Metabolic adjustments in breeding female kittiwakes (Rissa tridactyla) include changes in kidney metabolic intensity

Black-legged kittiwakes (BLKIs) reduce self-maintenance cost through reductions in mass-specific basal metabolic rate (BMR), body mass and the size of visceral organs during the chick-rearing period. In the present study, we measured kidney in vitro oxygen consumption and plasma 3,3',5-triiodo-L: -thyronine (T3) levels of incubating and chick-rearing female BLKIs, to test whether the decrease in BMR is caused mainly by decreased metabolic intensity or simply by reductions in the size of organs with high metabolic intensity. Body mass and body condition were lower in chick-rearing birds compared with the incubating birds. In contrast to the previous findings, however, the kidney mass did not differ between the two breeding stages. Plasma T3 levels decreased substantially during the breeding season, indicating a reduction in BMR. Over the same period, kidney mass-specific oxygen consumption decreased (by 17.2%) from the incubating to the chick-rearing stage. Thus, the reduction in BMR found in breeding BLKIs seems partly explained by adjustments in metabolic intensity of visceral organs. Lowered metabolic intensity of visceral organs would permit increased allocation of energy to offspring at the expense of their own self-maintenance.

The effect of temperature and salinity on oxygen consumption in the brachyuran crab Cyclograpsus punctatus (Crustacea: Decapoda: Grapsidae)

The aquatic oxygen consumption of the estuarine brachyuran crab, Cyclograpsus punctatus, was investigated after a 24-hour acclimation period at different temperature (12.5, 20, 30°C) and salinity (9, 17.5, 35, and 44°) combinations . Salinity had no significant effect on oxygen consumption at 12.5 and 20°C in both large and small crabs. At 30°C and 44°, however, the rate of oxygen consumption declined in large crabs (from 0.233 to 0.176 mg O2 g wwt/h) and increased in small crabs (0.300 to 0.469 mg O2 g wwt/h). There was also a significant increase in the oxygen consumption (0.300 to 0.536 mg O2 g wwt/h) of small crabs at the high temperature/low salinity combination. Temperature had a significant effect on the rate of oxygen consumption at all salinities, with Q10 values ranging from 1.16 to 2.85. In all cases the mass-specific oxygen consumption rate of small crabs was higher than that of large crabs. The results suggest that the confinement of this species to the lower reaches of estuaries may, in part, be due to physiological constraints on juveniles and small individuals.