Weight-specific Respiration Rate Research Articles

Effect of in-situ simulated light levels on respiration rate of <italic>Euphausia superba</italic> in winter

As the key species in the Southern Ocean, how Antarctic krill (<italic>Euphausia superba</italic>, hereafter krill) survives through the extremely severe winter time is always one of the key issues for krill ecology. Krill can utilize different strategies to tackle the long winter time, and in which the most effective pattern is to decrease the metabolism and subsequently to reduce the energy consumption. The studies available indicate that the lighting condition could be the key of low energy consumption pattern; however, the in situ data are extremely limited. The oxygen consumption rate usually reflects the metabolic rate of organisms. Therefore, in order to explore the effect of in situ lighting conditions on the metabolism of krill, this study measured the oxygen consumption of krill during the successive 11 days under dark and lighting conditions based on the in situ aquarium experiment. In the experiment, the krill was placed in a closed bottle, and the respiration rate of the krill over a period of time was obtained by measuring the difference in the oxygen concentration of the seawater in the bottle before and after the experiment. A robust linear simulation method was used to eliminate the influence of outliers on the trend of daily variation in respiration rate of krill. Results showed that the average weight specific respiration rate of krill under light conditions was (0.270 4 ± 0.074 0) μL · (mg·h) ^-1, and the average weight specific respiration rate under dark conditions was (0.267 3±0.084 0) μL ·mg (·h) ^-1. In this study, in a period close to a natural day, the experimental group of krill was repeatedly tested by changing the conditions of darkness and 100 lx light intensity. The experimental results showed that the oxygen consumption level of krill did not show significant fluctuation. The comparative analysis demonstrated that the oxygen consumption of krill in the winter was significantly lower than that in the summer. The change of lighting condition within a natural day did not impact significantly on oxygen consumption of krill, but the stability of respiration rate of krill was impacted. The study supported the observation that krill was on low metabolism pattern during the winter time, and the stability of such pattern was also proved. The conclusion in the study will provide important basic data for revealing the overwintering mechanism of krill.

Routine metabolism of Antarctic krill (Euphausia superba) in South Georgia waters: absence of metabolic compensation at its range edge

Routine respiration rates in the South Georgia stock of Antarctic krill (Euphausia superba) were measured to compare with previously published measurements on stocks from colder locations further south. Within the natural temperature range of this species (− 1.8° to 5.5 °C), respiration rate data from both the present and previous studies were adequately fitted by a single Arrhenius regression (Q10 of 2.8), although South Georgia krill showed an upward deviation from this regression between 0° and 2 °C (the lower temperature range at South Georgia). Metabolic compensation (i.e. the comparative lowering of respiration rate) at the high temperatures experienced at South Georgia was not apparent, although the higher than predicted metabolic rates at low temperatures suggests acclimation of South Georgia krill to a warm water lifestyle. Weight-specific respiration rate was significantly higher in sub-adults and adults compared to juveniles, highlighting the metabolic burden of reproduction. South Georgia krill showed no further increase in respiration rate when exposed to acute temperatures (5.5–12.2 °C), indicating that they were already at the limit of aerobic capacity by 5.5 °C. Overall, this study shows that even small degrees of additional warming to South Georgia waters are likely to make conditions there metabolically unsustainable for Antarctic krill.

Scaling relationships based on partition coefficients and body sizes have similarities and interactions†

The LC50 of compounds with a similar biological effect, at a given exposure period, is frequently plotted log–log against the octanol–water partition coefficient and a straight line is fitted for interpolation purposes. This is also frequently done for physiological properties, such as the weight-specific respiration rate, as function of the body weight of individuals. This paper focuses on the remarkable observation that theoretical explanations for these relationships also have strong similarities. Both can be understood as result of the covariation of the values of parameters of models of a particular type for the underlying processes, while this covariation follows logically from the model structure. The one-compartment model for the uptake and elimination of compounds by organisms is basic to the BioConcentration Factor (BCF), or the partition coefficient; the standard Dynamic Energy Budget model is basic to the (ultimate) body size. The BCF is the ratio of the uptake and the elimination rates; the maximum body length is the ratio of the assimilation (i.e. uptake of resources) and the maintenance (i.e. use of resources) rates. This paper discusses some shortcomings of descriptive approaches and conceptual aspects of theoretical explanations. The strength of the theory is in the combination of why metabolic transformation depends both on the BCF and the body size. We illustrate the application of the theory with several data sets from the literature. †Presented at the 12th International Workshop on Quantitative Structure–Activity Relationships in Environment Toxicology (QSAR2006), 8–12 May 2006, Lyon, France.

Effect of body weight, temperature and feeding on the metabolic rate in the spiny lobster Panulirus argus (Latreille, 1804)

Spiny lobsters are prevalent in tropical and temperate seas and support some of the largest commercial fisheries in the world. Studies on the metabolic rate of spiny lobsters contribute to the understanding of the relation of these widely distributed crustaceans with their environment, to the design of holding facilities and to the development of future aquaculture technologies. The current study attempts to describe the oxygen consumption of juvenile lobsters Panulirus argus in relation with body weight, temperature and feeding. Individual routine metabolism increased with body weight according to the regression line Log 10 MO 2 (mg O 2/h) = 0.754Log 10 W (g) − 0.678 ( r 2 = 0.71) whereas weight-specific respiration rate decreased according to the regression line Log 10 VO 2 (mg O 2/kg/h) = − 0.774Log 10 W (g) + 3.395 ( r 2 = 0.81). The metabolism of juvenile P. argus showed a linear increase with temperature and this relationship was best described by the regression line VO 2 (mg O 2/kg/h) = 6.183 T (°C) − 110.21 ( r 2 = 0.72). All regressions were found to be statistically significant. From the evaluated factors, feeding had the highest effect on oxygen consumption. The oxygen consumption increased after ingestion with the maximum within the first 5 h. Results are discussed in relation with their relevance for maintaining P. argus under captive conditions.

Respiratory adaptations to oxygen lack in three species of Glossiphoniidae (Hirudinea) in Lake Esrom, Denmark

The weight-specific respiration rate (μl O 2 mg −1 AFDW h −1) of three species of leech from Lake Esrom, Denmark, Glossiphonia concolor, G. complanata and Helobdella stagnalis was measured in a closed stirred chamber with a micro electrode. At declining oxygen concentration (mg O 2 l −1) all three species expressed moderate ability to regulate respiration, in G. concolor and G. complanata down to 2 mg O 2 l −1, in H. stagnalis down to 0.75 mg O 2 l −1. Survival in anoxia was measured in closed bottles. The time to 50% survival (LD 50) was 30 days in G. concolor at 20 °C and 30 and 4 days in H. stagnalis at 10 and 20 °C, respectively. The results were discussed in relation to habitat and spatial distribution of the three species in the lake.

Respiration rates of Beroe ovata in the Black Sea

Metabolic rates of the ctenophore Beroe ovata within the length range from 0.4 mm (newly hatched larvae) to 60 mm were investigated. At 20°С the respiration rates (Q, µg O2 ind.−1 h−1) of individuals with wet weights (W, mg) less than or greater than 100 mg changed according to the equations Q=0.093W 0.62 and Q=0.016W 0.99, respectively. The weight-specific respiration rate of the juvenile ctenophores with wet body weights of 0.021–100 mg diminished approximately 20-fold (from 0.35 to 0.017 µg O2 mg−1 h−1, respectively), but did not change within the range from 100 to 30,000 mg. The difference in the slope of the regression lines seems to be attributable to the ontogenetic changes in B. ovata metabolism. For the tested temperature range of 10–28°С, the mean Q 10 coefficient was equal to 2.17±0.5. The basal metabolism of B. ovata narcotised by chloral hydrate was 4.5±0.9 times lower than total metabolism. Such a metabolic range is considered to be characteristic of aquatic invertebrates with high levels of locomotory activity.

Physiological characteristics of the ctenophore Beroe ovata in Caspian Sea water

5 Iranian Fisheries Research Organization (IFRO), No. 297, Fatemi St., Tehran, Iran ABSTRACT: Riparian countries of the Caspian Sea have been evaluating the pros and cons of the predatory ctenophore Beroe ovata as a control agent against the invasive ctenophore Mnemiopsis leidyi, which has enormous adverse impacts on the fishery resources as well as on the biodiversity in this once fertile sea. To assess the viability of B. ovata establishment in the Caspian Sea, the survival and some physiological characteristics (feeding, respiration, reproduction and growth) of the preda- tory ctenophore were studied in Caspian Sea water (12.6 ppt salinity) conditions using animals trans- ported from the Black and Marmara Seas to a laboratory on the Iranian Caspian coast. The findings of the study showed that when salinity was gradually decreased from 22 to 12.6 ppt, B. ovata were able to adapt well to Caspian Sea water. Most of the predatory ctenophores began to swim actively and to feed on M. leidyi within 15 to 30 min following each step of acclimation. The feeding rate of B. ovata ranged from 14 to 765% of body wet weight and was highest for smaller individuals (i.e. 13 to 16 mm). Over the measured weight range of 0.23 to 3.87 g wet wt, the weight-specific respiration rate was independent of weight. The daily specific growth rate of adult ctenophores was 7 to 11% of body wet wt. B. ovata specimens were spawned and their eggs were hatched in Caspian Sea water, but the larvae survived for only a few hours. The energy budget of B. ovata calculated from food consump- tion, respiration and growth rates revealed a mean assimilation efficiency of 0.72 ± 0.1, a gross growth efficiency (K1) of 0.48 ± 0.12 and a net efficiency (K2) of 0.66 ± 0.06. Based on these physio- logical data, we suggest that in the Caspian Sea, B. ovata will be able to ingest M. leidyi intensively. However, concerning the reduction of the M. leidyi population and consequently the reversal of its adverse impact on this ecosystem, the failure of larval growth observed under experimental condi- tions (most probably due to poor handling) remains the main obstacle to overcome in the successful establishment of B. ovata in the Caspian Sea.

In situmacrofaunal respiration rates and their importance for benthic carbon mineralization on the northwestern Black Sea shelf

Abstract Benthic fauna assemblages and organic carbon mineralization processes were studied in the northwestern Black Sea along a transect from the well-oxygenated shelf to the (deep) anoxic basin. Bivalves dominated the coenoses at the three oxygenated stations, but with decreasing macrofaunal biomass at increasing water depth. The previously well-described zonation of macrofaunal communities for the northwestern shelf of the Black Sea was also found in this study (Mytilus galloprovincialis coenosis at Station 1 (62 m), Modiolus phaseolinus coenosis at Station 2 (77 m) and 3 (100 m)). The highest meiofauna density was found at the transition from oxic to anoxic bottom waters (Station 4, 130 m, < 5 μM O2). Reduced predation and sufficient food supply are suggested to be of importance at that site. The weight-specific fauna-mediated respiration rate of the mussel community was independent of water depth and always around 14 nmol O2 mg ww-1 d-1. Thus indicating that the mussel communities on the northwester...

Differentiation of physiological aspects of the burrowing shrimp Callianassa tyrrhena in relation to general pollution load

Two aspects of the physiology of the burrowing shrimp Caliianassa tyrrhena (Decapoda: Thalassinidea) were studied in order to investigate the effects of the general pollution load: total (TRR) and weight-specific respiration rate (SRR) as well as the digestive enzyme activity of the digestive gland.Caliianassa tyrrhena exhibited a very low respiration rate (mean TRR=64-29 μl 02 animal−1h−1, N=60; mean SRR=0·18 μl 02mg DW−1h−1, N=61).The slope of the TRR-DW logarithmic regression (b=0·64) showed that respiration in C. tyrrhena is proportional to body surface. Size is the dominant factor (among size, sex, season and locality) determining the variation in respiration rate. Comparison between the two sites with the different pollution load showed that there were no significant differences in the respiration rates of the same size class and season, except for the youngest animals in summer which showed a significant decrease in their respiration rate at the polluted site.A similar ‘inhibitory’ effect of pollution has been observed in the activity of the majority of the 19 digestive enzymes tested. Only three e.g., trypsin, β-galactosidase and α-glucosidase showed an increase in polluted waters.One could suggest, therefore, that C. tyrrhena can be considered to be preadapted to the low oxygen conditions encountered in the sediments, because of its burrowing mode of living.

Effect of age and weight-specific respiration rate on toxicity of esfenvalerate pulse-exposure to the Australian crimson-spotted rainbow fish ( Melanotaenia fluviatilis)

The acute toxicity of a 1-h pulse-exposure with the synthetic pyrethroid pesticide, esfenvalerate, to Australian crimson-spotted rainbow fish ( Melanotaenia fluviatilis) of different ages was measured. The effects of esfenvalerate were measured on embryos 1, 2, 4, 8, 24, 72, and 144 h post-fertilisation, and on larvae <2 days, 3–4, 7–8, 14–16, 28–32, and 90 (sexually mature) days old. The effects of rainbow fish age and esfenvalerate exposure on weight-specific metabolism were also recorded and we tested the hypothesis that there was a significant correlation between the 1-h pulse-exposure 96-h LC 50, and weight-specific respiration rate. The eggs of the rainbow fish were not sensitive to esfenvalerate, although the pesticide was highly toxic to larvae less than 1 week old. The mean (s.e.) 96 h LC 50's following a 1-h pulse-exposure to esfenvalerate were 2.32 (0.70), 1.07 (0.26), 28.11 (14.46), 33.42 (10.21), 48.04 (13.34) and 3960 (157) μg 1 −1 for rainbow fish <2 days, 3–4, 7–8, 14–16, 28–32, and 90 days old, respectively. There was a significant negative correlation between weight-specific respiration rate and the toxicity of pulse-exposed esfenvalerate, although esfenvalerate did not affect the respiration rate directly. We postulate that the observed decrease in toxicity of esfenvalerate with increasing age was due to lower uptake of the pesticide on a weight basis.

Growth and energetics in the ascidian Ciona intestinalis

Rates of growth, filtration and respiration of the ascidian Ciona intestinalis (L.) were measured in the laboratory in the presence of food (flagellate Rhodomonas sp.) concentrations ranging from 0 to 12000 cells ml-' (0 to 500 pg C I-'). Weight-specific growth rate (dry weight of body parts not including the tunic) increased sigrnoidally with increasing algal cell concentration to 7.7 % d-' Maximum specific growth rate was related to age rather than size. A condition index (C1 = DWw@Wrotal) reflected level of growth. Specdic filtration rate decreased logarithmically with increased algal cell concentration. Weight-specific respiration rate showed a relation to algal cell concentration similar to that shown by weight-specific growth rate. All rates were transformed into units of carbon, and a carbon budget was established for 2 size groups. Assimilation efficiency (AE) was approximately 50% but decreased at the highest carbon concentrations. The amount of carbon assimilated per body unit that was needed to maintain body (not including the tunic) or total (including the tunic) carbon was independent of initial size and amounted to 10 or 16 pg C mg C' d' , respectively. Gross growth efficiency (GGE) and net growth efficiency (NGE) varied with food concentration and approached a level of 0.23 or 0.78, respectively, in terms of body carbon. In terms of total carbon, GGE was found to be 0.27 to 0.28 and NGE to be 0.79. Costs of maintenance were greater in the largest ascidians, while costs of body growth were equal in the 2 size groups (0.21 to 0.23).

Zooplankton community respiration during the JGOFS pilot study

From March to July 1989 (JGOFS pilot study), measurements were carried out on the oxygen uptake of natural zooplankton communities on five drifting stations (about three weeks each) in the Atlantic from 18°N to 72°N after a method of Martens (1986). The weight specific respiration rate decreased from south to north parallel to the water temperature, whereas the amount of mesozooplankton increased. No significant differences in the oxygen uptake of the zooplankton community between the five stations could be found. A rough estimate showed that less than 2% of the phytoplankton carbon was assimilated by the mesozooplankton per day. This is thought to reflect a typical spring situation. The weight specific respiration rate is influenced significantly by the water temperature and the mean length of the zooplankter.

Relative respiration and feeding rates of oyster and brackish water clam in variously contaminated waters

Oysters ( Crassostrea virginica) and brackish water clams ( Rangia cuneata) were acclimated in situ to water from two different Chesapeake Bay tributaries. Following acclimation, their respiratory and feeding rates were determined in ∼ 1 l. recirculating chambers. Mean oyster respiration rate varied between 0.58-2.21 mg O 2 g −1 h −1, depending upon acclimation water quality. Mean clam respiratory rates varied between 0.028-0.251 mg O 2 g −1 h −1. The weight specific respiration rate of the clams was 0.106+0.213 log 10 dry wt. Mean feeding rate for oysters ranged between 4.25-9.63 l g −1 h −1. Mean feeding rates for clams varied between 0.38 and 0.72 l g −1 h −1. The weight specific feeding rate of the clams was 0.563+0.519 log 10 dry wt. R. cuneata was shown to be a potentially useful species for monitoring environmental pollution in the fresh-saltwater interface of estuaries.

Energy partitioning during larval development of the hermit crab Pagurus bernhardus reared in the laboratory

Hermit crab Pagurus bernhardus larvae were reared under constant conditions in the laboratory, and their growth and respiration were measured at short intervals (every 1 or 2 days) in terms of dry weight, CHN, and oxygen consumption, respectively. These measurements were converted to energy equivalents, in order to construct energy budgets for the successive larval instars. Instantaneous growth rates were constant in the zoea I, but showed a decreasing trend during all following zoeal moult cycles. The megalopa does not eat and consequently loses energy during its development. A decreasing C:N ratio indicates degradation of nonproteinaceous reserves (presumably mainly lipids) as an energy source during this stage. Individual respiration ( R) increased in the first two zoeal instars as a linear function of time, then it showed a stepwise increase, with constant values during the zoea III and IV moult cycles. The megalopa showed maximum R during early postmoult, followed by significantly lower values during later stages of the moult cycle. In late premoult, however, a slight increase occurred in R, indicating enhanced metabolic activity with approaching metamorphosis. Moult-related increase in metabolic intensity of tissues was clearly shown also by a cyclic pattern in weight-specific respiration rate ( Q O 2 ) during larval development. The average Q O 2 decreased in general in subsequent larval instars with average body weight. Computer simulations of bioenergetic changes suggest a decreasing trend in net growth efficiency ( K 2) during individual zoeal moult cycles, in particular during the zoea III and IV. When integrated energy budgets are calculated, however, the overall K 2 values of the different zoeal instars are quite similar, with a somewhat higher value in the zoea I (0.58) than in the following three stages (0.44–0.47). Thus, energy partitioning does not reveal significant variation during zoeal development, whereas the megalopa deviates in all bioenergetic traits. As a consequence of secondary lecithotrophy, the ultimate larval stage respires ca. one half of total energy accumulated by the four zoeal stages combined. It is suggested that this peculiar energetic pattern in larval development of the hermit crab is an adaptation to its very specific habitat requirement at metamorphosis: the need for a gastropod shell.

Effects of body size and temperature on the metabolic rate of Penaeus monodon

Laboratory measurements of oxygen consumption were made on Penaeus monodon (Fabricius) from protozoea to adult stage at temperatures between 15° and 35°C. The logarithmic relationship between weight-specific respiration rate (WRt) and temperature (T) for two size groups, Protozoea 1 (PZ1) to Postlarva 1 (PL1) and PL to adult, are given as; WRt=100.431+0.0146 (T) (ml O2 g-1 h-1) and WRt=10-0.948+0.0338 (T) (ml O2 g-1 h-1), respectively. Additionally, equations relating metabolic rate, temperature and size for the two size groups are; PZ1-PL1: log M=0.431+0.0146T+(1.25 (log TL)+0.579), and PL1-adult: log M=-0.948+0.0338T+(2.60(log CL)-0.683), where M=oxygen consumption in ml O2 individual -1h-1, T=temperature in °C, TL=total length in cm, and CL=carapace length in cm. Activation energies of 6 186.75 J for PZ1-PL1 and 14 066.62 J for PL-adults point to different metabolic pathways or to differences in the ratio between the metabolic pathways used.

Respiration and growth of Hyas araneus L. Larvae (Decapoda:Majidae) from hatching to metamorphosis

Rates of respiration and growth were measured for larvae of the spider crab Hyas araneus L., reared in the laboratory from hatching to metamorphosis. The moulting cycle was simultaneously monitored. In both zoeal instars individual respiration rate ( R) increased as a linear function of time ( t) of development, whereas growth, measured as dry weight ( W), carbon (C), nitrogen (N), hydrogen (H), and energy content ( E, calculated from C) followed a power function of t. Weight-specific respiration rate ( QO 2) was in all instars maximum in early postmoult, and minimum in intermoult and early premoult. Zoea II and megalopa instars showed another conspicuous QO 2 increase during late premoult. Respiration (both R and QO 2)and growth of the megalopa could be described by non-linear (quadratic) functions of t. R and QO 2 during this larval stage were not correlated with W, but were controlled by events of the moulting cycle: R followed a similar pattern to QO 2 (minimum values in intermoult), whereas biomass of the megalopa changed conversely, with a maximum in intermoult and early premoult. The respiratory coefficient (i.e. the ratio of metabolic energy loss: energy gain by body growth) was far lower (<0.8) in the zoeal instars than in the megalopa (>5), suggesting a strongly reduced capability of energy conversion in the final larval stage of H. araneus.

Nutrient cycling in a microflagellate food chain: II. Population dynamics and carbon cycling

Carbon cycling in a 3-member food web containing a diatom (Phaeodactylurn tricornutum), bacteria, and a herbivorous/bacterivorous microflagellate (Paraphysornonas jmperforata) was examined. Ingestion of prey by the microflagellate was the primary mechanism for remineralization of particulate organic material. Approximately 65 % of the particulate organic carbon (POC) initially present was lost over the course of the 8 d experiments in cultures containing microflagellates. No significant increase in remineralization was observed when bacteria were present. Bacteria were responsible for the uptake of dissolved organic carbon (DOC), but their overall contribution to carbon cycling was small relative to that of the microflagellate. Microflagellates incorporated diatom and bacterial biomass with equal efficiency (44 %) during exponential growth. Only 10 % of the POC ingested by microflagellates was released as DOC while 10 % was released as egested POC. The relatively high weight-specific respiration rate of the microflagellates (X = 2.67 X nl O2 h-') coupled with their relatively small release of DOC indicates that herbivory by heterotrophic microflagellates may be a major mechanism for the regeneration of nutrients from living phytoplankton which circumvents bacterial decomposition.

Respiration, energy balance and development during growth and starvation of Carcinus maenas L. larvae (Decapoda:Portunidae)

In all larval stages of Carcinus maenas L. oxygen consumption was measured at three temperatures (12,18,25 °C). Values increased during development and were in the range of 0.037 ± 0.01 (zoea-1, 12°C, x ̄ ± 95% CL ) to 0.734 ± 0.047 μl O 2 · h −1 · ind −1 (megalopa, 25 °C). Growing larvae showed temperature dependent trends in weight specific respiration rates (referred to dry wt; DW), with values between ≈2.4 and 9.4 μl O 2· h −1·mg DW −1. Increase in oxygen consumption of megalops did not differ much at temperatures between 18 and 25 °C. This points to an exceptional physiological position of this stage. Fed zoea-1 of C. maenas (18 °C) revealed growth rates in terms of 40% DW, 20% carbon (C), 30% nitrogen (N) and 65% hydrogen (H). At the same time larvae gained individual energy by 13% (J · ind −1), while weight specific energy dropped by ≈ 19% (J · mg DW −1) during the first day and remained constant until the moult. Starved zoea-1 of C. maenas (18 ° C) gained ≈ 20 % in DW through the first day, probably caused by inorganic salts which enter the organism after the moult of the prezoea. DW dropped to ≈ 25 % of initial value, when starvation continued. Single components decreased by ≈50% (C), 54% (N), 57% (J · ind −1). Weight specific energy (J · mg DW −1) decreased by 40% during the first 4 days of starvation, remaining constant thereafter. Individual respiration rate ( R) dropped by 61 %, weight specific respiration rate ( QO 2) by 55 %. Individual energy loss in starved zoea-1 was 0.077 J over a period of 11 days. In this period ≈ 9.3 μl O 2·ind −1 were consumed. Thus effective oxygen capacity was lower than in growing larvae. It dropped to 5.3 J·mlO 2 −1 after 4 days and remained constant if starvation continued, i.e. 65 % of possible energy loss occurred during the first 4 days. Decrease in requirement for oxygen and its effective capacity were both recognized as independent components of survival during starvation. Partitioning of energy through individual larval development of C. maenas was investigated for all five larval stages. The cumulative budget could be calculated: consumption ( C) = 28.23 J, growth ( G) = 0.92 J, exoskeleton ( Ex) = 0.20 J, metabolism ( M) = 5.30 J, egestion and excretion ( E) = 21.82 J. Mean gross and net growth efficiency were, K 1 = 3.3% and K 2 = 14.8%, respectively.

Effects of temperature and salinity on oxygen consumption and nitrogen excretion in Thais (Nucella) lapillus (L.)

The 2-wk TLm of stepwise-acclimated Thais lapillus (L.) (>20 mm long) was 14.2–16.2%. salinity ( S) at 5, 10, 15, and 20°C. The same TLm occurred at 10 °C after direct transfer of snails to the final salinity but stepwise-acclimated small snails (<20 mm) tolerated a significantly lower salinity (12.7%. S). Oxygen consumption rates ( V ̇ O 2 ) fit the allometric equation V ̇ O 2 = a· W 0.60 ± 0.07 . Salinity and temperature had a significant effect on V ̇ O 2 , which was highest at 30%. S and depressed at 17.5%. S and at 5°C. Ammonia excretion rates fit the allometric equation V ̇ NH 4 + = a · W 0.61 ± 0.05 . Both salinity and temperature affected V ̇ NH 4 + . Ammonia excretion was significantly lower at 17.5 %. S than at higher salinities at 10, 15, and 20°C, but did not vary as a function of salinity at 5°C. Primary amines were lost from snails under all conditions without any obvious relationship with temperature or salinity. Primary-amine loss, expressed as a percentage of V ̇ NH 4 + , was significantly higher at 17.5 %. S than at higher salinities. Oxygen : nitrogen ratios ranged from 4.2–15.6, indicating protein was the primary metabolic substrate, and were highest at 15 °C and lowest at 5 °C. Snails withstood 89 days starvation without mortality at 10°C. Oxygen consumption of snails declined by 28% during starvation due to a 37% decline in dry weight; consequently, weight-specific respiration rate increased by 17%. The intercept ( a) for the V ̇ O 2 allometric equations did not change during starvation. Ammonia excretion increased during starvation, and primary-amine loss increased until Day 21, then declined. Oxygen: nitrogen ratios declined from 14 to 8, indicating an increased catabolism of protein during starvation.