Metabolic rate and cost of growth in juvenile pike (Esox lucius L.) and perch (Perca fluviatilis L.): the use of energy budgets as indicators of environmental change

Summary Energy budgets of juvenile pike and perch (weighing approximately 3 g) were determined in experiments lasting up to 4 days, by simultaneously measuring oxygen consumption, food consumption, and growth of individual fish. Although the basic pattern of energy allocation was identical in the two species, perch subjected to constant light (PEL) showed faster growth, higher assimilation and conversion efficiency, and higher oxygen consumption than perch subjected to a short daylength regime (PED). The efficiency with which food energy was converted into body mass was 39±5% in PED but 49±4% in PEL. However, the “work coefficient” (increment of body mass/post-prandial increase of oxygen consumption: mg · μmol O _inf2 ^sup−1 ) differed only insignificantly between the two groups of perch, indicating that the metabolic cost of growth was unaffected by the manipulation of experimental conditions. This identifies the higher assimilation efficiency, i.e. the increased flow of food energy into the tissues as being the cause of accelerated growth of perch under the constant-light regime. In both species the maximum feeding-induced metabolic rate was 4 times higher than the lowest preprandial rate. In perch (which were kept on low rations before the experiments) the post-prandial metabolic rate increased steadily from day to day during the 4-day experiments, so that on the last day the rate of oxygen consumption exceeded the rate on the first day by about 41%. This investigation provides further evidence that the allocation of metabolic energy in fish is based on a flexible strategy which responds sensitively to changes in both internal and external conditions.     

Daily ration of adult perch, Perca fluviatilis L. during summer in Loch Leven, Scotland

Adult perch, Perca fluviatilis L., were sampled at 3-hourly intervals throughout 24-h periods from June-September 1971, and in June and August 1972. The wet weight of each major food component from the stomachs was expressed in parts per 10 000 of the fresh weight of the fish. From samples at capture, and others taken from caged fish at known time-intervals after capture, the rate of stomach evacuation was estimated. Food consumption between netting times was calculated as the increment between successive initial values of stomach contents, plus the amount evacuated in the interval. As the evacuation rate of caged fish was slower than that of free fish the estimates of food turnover are minimal ones. The perch were consuming 6.5 % of their wet body weight per day in June, and this ration had decreased to 3.2% by September.     

Effects of temperature on allocation of metabolic energy in perch (Perca fluviatilis) fed submaximal rations

Growth and long-term trends of oxygen consumption were monitored at 15 and 20° C in spontaneously swimming juvenile perch fed a fixed daily submaximal ration. The average rate as well as the efficiency of assimilation were the same at the two temperatures but a much higher proportion of food energy was allocated to activity and maintenance, and a correspondingly lower proportion to growth, at 20 than at 15° C. By computing average specific rates of oxygen consumption separately for all light and dark periods, it was found that at 20, but not at 15° C, the' scope for spontaneous activity' of two consecutive (dark and light) phases of a diurnal cycle was indirectly proportional to the average rate of oxygen consumption in the dark phase. This indicates that at 20° C the perch displayed partial compensation for a high metabolic rate in the dark by reducing swimming activity in the following light phase. However, the overall effect of this behaviour was probably too small to make a noticeable impact on the low conversion efficiency in the juvenile perch at 20 as compared to 15° C.     

Influence of food ration, copper exposure and exercise on the energy metabolism of common carp (Cyprinus carpio)

The present study was conducted to extend the understanding of the combined physiological effects of different food rations in combination with sublethal levels of copper in common carp (Cyprinus carpio). Fish acclimated to low (0.5% body weight) and high (5% body weight) food rations were exposed to 1 microM copper for a period of 28 days and kept for a further 14 days in copper free water to examine their recovery. Measurements of oxygen consumption, ammonia excretion and ammonia accumulation in plasma and muscle were done at various time intervals during the experimental period. Overall, oxygen consumption and ammonia excretion rates were significantly affected by food ration in both copper free and copper exposed fish. Additional challenges, such as copper exposure and/or exercise, significantly increased plasma and muscle ammonia in the fish fed a high food ration. Muscle ammonia levels in general responded slower (first increase after 72 h) and recovered within 2 weeks of exposure. There was a significant correlation between plasma ammonia levels, muscle ammonia levels and ammonia excretion rates. Influence of copper in terms of ammonia excretion and plasma ammonia accumulation was observed in high ration fish but low ration fish remained unaffected. This clearly indicates that ammonia metabolism was significantly influenced by copper in this group of fish showing that during unfavourable environmental conditions a high amount of food supply may turn deleterious to fish.     

Seasonal changes in growth and standard metabolic rate of juvenile perch, Perca fluviatilis L.

The maximum growth rate of juvenile perch, PercaJuviatilis L., at different constant temperatures and in naturally changing day-lengths was studied in the laboratory. Standard metabolic rate was studied in starvation experiments at constant temperatures under short- and long-day conditions. Growth occurred in temperatures above 8 to 10°C. In winter, from mid-October until mid-April, maximal growth was considerably reduced and was relatively slow but constant. The standard metabolic rate was reduced c . 50% under short-day conditions. The seasonal change in metabolic rates, presumably controlled by an endogenous rhythm, was considered to be an adaptation to low food availability during the short winter days.     

A study of the food and feeding of perch, Perca fluviatilis L., in Windermere

SUMMARY. Perch were sampled for their stomach contents at regular intervals throughout 24 h from June until October in 1973 and from February 1975 until January 1976. They were found to feed on benthic organisms from November until April, on benthos and plankton during May and June and on perch fry and zooplankton from July until October. Perch over a wide size range feed on similar prey. Fish showed great variability in the weight of their stomach contents. A method based on a points system was developed to estimate the weight of food in the stomach for a given weight of fish at a known time. A diel feeding pattern which varied with the season was apparent from these data. Rates of gastric evacuation were assumed to be exponential and were calculated from the drop in night-time stomach content weights when food intake was assumed to be zero. The rates ranged from 0.18 mg h⁻¹ at a mean water temperature of 11°C in May to 0.35 mg h⁻¹ at a mean water temperature of 17°C in July. Assuming that food consumption followed a linear rate of intake, the standard Bajkov method was considered an adequate model to calculate daily food consumption. Daily food consumption (mg dry weight) was calculated for 150 g perch for all months of the year (November to April and September and October being combined). A second series of values was calculated making corrections for the time spent in the fishing gears when food intake was zero but gastric evacuation continued. Daily food consumption figures for 150g male perch based on Winberg's hypotheses (1956) and growth data showed no significant differences from this second series of values, when both were expressed in energy terms. When certain assumptions have been tested, growth data and Winberg's equations together may be a suitable method for calculating an energy budget for the Windermere perch population.     

Effects of temperature and ration level on the growth and food conversion efficiency of Salmo gairdneri, Richardson

The effects of temperature and ration size on the growth rate and gross efficiency of food conversion of juvenile rainbow trout Salmo gairdneri were evaluated during 25-day seasonal experiments. Rations ranged from near-starvation to repletion levels. Test temperatures were 3 and 6°C higher than the controls which fluctuated dielly and seasonally. At rations near maintenance, elevated temperatures decreased trout growth. As the feeding rate increased the detrimental effect of temperature on growth was ameliorated. At repletion feeding levels, elevated temperature up to 17°C improved trout growth by increasing the maximum food consumption rate. With a temperature increase from 6.9 to 22.5°C maintenance rations increased from 2.2 to 7.5 % body weight per day. Gross efficiency was dependent upon ration level and temperature. As the food consumption rate increased, efficiency increased to a maximum, then generally declined at repletion levels. Elevated temperatures resulted in reduced efficiencies at low consumption rates but temperatures had little effect at high ration levels. A field study provided estimates of the food consumption relationships established in the laboratory, suggested any substantial increase of stream temperature without a concomitant increase of food abundance would result in decreased trout production.     

An application of a bioenergetics model to Eurasian perch (Perca fluviatilis L.)

A bioenergetics model was developed for Eurasian perch ( Perca fluviatilis L.) by revising an existing model for yellow perch and walleye. Data were gathered from field studies and the literature. Besides adjusting the original parameters of the model, effects of season on consumption and metabolic rates were added. The predictive capability of the revised model was high both concerning the levels of growth and its seasonal development in the Baltic coastal waters to which the model was applied. Perch young-of-the-year attained almost maximum consumption and growth except in the highest temperatures experienced. In larger fish, the model estimated consumption to be about 50 per cent of the maximum possible rate.     

Energetics and metabolic correlates of starvation in juvenile perch (Perca fluviatilis)

Long-term measurements of the diurnal pattern of oxygen consumption were conducted in fasting juvenile perch at 15 and at 20° C. In addition, dry body mass, protein and glycogen concentrations and the activity of two key enzymes of energy metabolism, phosphofructokinase and glutamate pyruvate transaminase, were monitored during the period of food deprivation. The average rate of oxygen consumption decreased during the starvation period, but the regular diurnal pattern of low rates in the dark and high rates in the light was upset by a break around days 7 to 8 at both temperatures. This break coincided with the exhaustion of the glycogen reserves in the muscles and in the liver, indicating that switching to a new energetic fuel was accompanied by a change in the pattern of swimming activity. Choice of the major energy source after exhaustion of the carbohydrate store was substantially influenced by water temperature. A negative correlation was found between the scope for spontaneous activity and the specific rate of oxygen consumption in the dark phase suggesting that the resting rate of metabolism responded more strongly to food deprivation than the rate of spontaneous activity in the light phase.     

Metabolic flux analysis of hybridoma continuous culture steady state multiplicity.

Physiological state multiplicity was observed in continuous cultures of the hybridoma cell line ATCC CRL-1606 cultivated in glutamine-limited steady state chemostats. At the same dilution rate (0.04 h-1), two physiologically different cultures were obtained which exhibited similar growth rates and viabilities but drastically different cell concentrations (7.36 x 10(5) and 1.36 x 10(6) cells/mL). Metabolic flux analysis conducted using metabolite and gas exchange rate measurements revealed a more efficient culture for the steady state with the higher cell concentration, as measured by the fraction of pyruvate carbon flux shuttled into the TCA cycle for energy generation. The low-efficiency steady state was achieved after innoculation by growing the cells in a nutrient rich environment, first in batch mode followed by a stepwise increase of the dilution rate to its set point at 0.04 h-1. The high-efficiency steady state was achieved by reducing the dilution rate to progressively lower values to 0.01 h-1 resulting in conditions of stricter nutrient limitation. The high energetic efficiency attained under such conditions was preserved upon increasing the chemostat dilution rate back to 0.04 h-1 with a higher nutrient consumption, resulting in approximate doubling of the steady state cell concentration. This metabolic adaptation is unlikely due to favorable genetic mutations and could be implemented for improving cell culture performance by inducing cellular metabolic shifts to more efficient flux distribution patterns.     

Temperature, growth and dietary effects on fish mercury dynamics in two Ontario lakes

A bioenergetics-based model was used to investigate the effects of temperature, growth and dietary exposure on methylmercury dynamics in walleye (Stizostedion vitreum) and yellow perch (Perca flavescens) from two lakes sampled in northwestern Ontario. Orange Lake was smaller, warmer, had slower fish growth and higher mercury concentrations in yearling yellow perch and walleye (three fold difference in 40 cm walleye) than Trout Lake. The model was applied to test the hypothesis that higher water temperatures in Orange Lake increased metabolic needs, food consumption and mercury uptake in fish. The effects of different growths rates in the lakes were also considered. Temperature/metabolic effects and growth effects on internal methylmercury dynamics in walleye and perch were predicted to occur but be of secondary importance. Different dietary exposure to methylmercury was likely the dominant source of variation in fish mercury concentrations between the two lakes.     

Seasonal energetics of northern phocid seals

The metabolic rate of harp (Pagophilus groenlandicus), harbor (Phoca vitulina), and ringed seals (Pusa hispida) was measured at various temperatures in air and water to estimate basal metabolic rates (BMRs) in these species. The basal rate and body composition of three harp seals were also measured throughout the year to examine the extent to which they vary seasonally. Marine mammalian carnivores generally have BMRs that are over three times the rates expected from body mass in mammals generally, both as a response to a cold-water distribution and to carnivorous food habits with the basal rates of terrestrial carnivores averaging about 1.8 times the mean of mammals. Phocid seals, however, have basal rates of metabolism that are 30% lower than other marine carnivores. Captive seals undergo profound changes in body mass and food consumption throughout the year, and after accounting for changes in body mass, the lowest rate of food intake occurs in summer. Contrary to earlier observations, harp seals also have lower basal rates during summer than during winter, but the variation in BMR, relative to mass expectations, was not associated with changes in the size of fat deposits. The summer reduction in energy expenditure and food consumption correlated with a reduction in BMR. That is, changes in BMR account for a significant portion of the seasonal variation in energy expenditure in the harp seal. Changes in body mass of harp seals throughout the year were due not only to changes in the size of body fat deposits, but also to changes in lean body mass. These results suggest that bioenergetics models used to predict prey consumption by seals should include time-variant energy requirements.     

Quantitative food utilization and reproductive allocation by adult milkweed bugs, Oncopeltus fasciatus

ABSTRACT. Age-specific and lifetime dry mass budgets were estimated for mated and virgin adult milkweed bugs, Oncopeltus fasciatus (Dallas) Hemiptera: Lygaeidae), fed air-dried milkweed seeds ( Asclepias syriacd ) in the laboratory at LD 14:10 and 23°C. Relative consumption rate (RCR) of all bugs was high during the first 8 days posteclosion (teneral period) as their fresh weight, dry weight, and fat content increased. Thereafter, the physiological syndrome associated with reproduction in mated females was indicated by their higher RCR, earlier and greater rate of egg production, greater lifetime relative metabolic rate and higher net and gross production efficiencies than virgin females and males. Males tended to live longer than virgin and mated females, which had similar lifespans. Mated females weighing less at eclosion remained lighter in weight on the day of mean peak weight, but food consumption, egg production and lifespan were independent of body-weight over a 25% range. Input of nymphal reserves or male reproductive secretions to egg production is probably minor in comparison with the adult female's food budget. The high proportion of the food budget allocated to egg production by mated females of O.fasciatus is consistent with its migratory, colonizing lifestyle.     

Photophosphorylation during Chloroplast Development in Red Kidney Bean: II. Photophosphorylation and Photoreduction Appear Concomitantly but Initially are Uncoupled

Cyclic phosphorylation with phenazine methosulfate and noncyclic phosphorylation and reduction with ferricyanide were detected in isolated chloroplasts from greening bean leaves after 3 to 4 hours of illumination. Activity commenced when rapid synthesis of chlorophyll was initiated. Rates of photophosphorylation were comparable to mature levels by 15 to 18 hours of development. Photoreduction of ferricyanide attained a peak value by 12 hours of illumination and subsequently fell to normal levels by 15 to 18 hours. With ferricyanide, the P/e₂ ratios were initially less than 0.1 but were close to 1.0 after 18 hours of illumination. The data suggested that photosystems I and II appeared concomitantly in the chloroplast but were not fully operative until later in development. Proplastids and immature chloroplasts exhibited high capacities to reduce ferricyanide in the dark. The rates of dark reduction rapidly diminished to low levels by 15 hours of illumination when normal rates of photochemical activity were observed. After a 2-to 3-day lag, a rapid increase in leaf fresh weight was noted at the time total chlorophyll content reached steady state values on a fresh weight basis. With fresh weight as an index of growth, primary leaves completed their development after 6 to 7 days of illumination.     

The estimation of food consumption in larval and juvenile fish: experimental evaluation of bioenergetics models

The two most commonly used methods for estimating the food consumption of fish are based on either the evacuation rate of food or the energy budget of an individual fish. In this study, both of those methods were used to estimate the food consumption of fish under experimental conditions. Bioenergetics models of vendace Coregonus albula , smelt Osmerus eperlanus , roach Rutilus rutilus and perch Perca fluviatilis were reconstructed based on experimental data and published values. The precision of the bioenergetics estimates for food consumption was evaluated under experimental conditions. The modelling efficiency (EF) of the bioenergetics model was 0.90, 0.97 and 0.93 for coregonids, roach and perch, respectively, which indicated good agreement between observed and predicted values. Under our experimental conditions, the bioenergetics model estimated food consumption better than the evacuation rate model.     

Energy turnover and the production of ammonium by the kidney: effect of hypernatremia.

The purpose of this study was to explore further the relation between the rates of oxygen consumption and ammonium (NH4+) production in the kidney during chronic metabolic acidosis. The experimental model was the dog with chronic metabolic acidosis because of the extensive background literature in this species. Chronic metabolic acidosis was produced by the ingestion of 10 mmol NH4Cl/kg body weight for 5 days. There was a significant increase in the rate of oxygen extraction when hypernatremia was present. Despite this rise in the rate of oxygen consumption, there was no increase in the rate of NH4+ production nor in the rate of glutamine extraction. These data suggest that hypernatremia might prevent a further augmentation in glutamine extraction when the rate of oxygen consumption rises. In addition, a larger proportion of the NH4+ produced was excreted in the urine during hypernatremia. This increase was associated with a rise in the urine flow rate, but not with a fall in urine pH.     

Lazy males? Bioenergetic differences in energy acquisition and metabolism help to explain sexual size dimorphism in percids

1. Differences in energy use between genders is a probable mechanism underlying sexual size dimorphism (SSD), but testing this hypothesis in the field has proven difficult. We evaluated this mechanism as an explanation for SSD in two North American percid species--walleye Sander vitreus and yellow perch Perca flavescens. 2. Data from 47 walleye and 67 yellow perch populations indicated that SSD is associated with the onset of maturation: typically, males of both species matured smaller and earlier and attained a smaller asymptotic size than females. Males also demonstrated equal (perch) or longer (walleye) reproductive life spans compared with females. 3. To examine whether reduced post-maturation growth in males was due to lower energy acquisition or higher reproductive costs we applied a contaminant mass-balance model combined with a bioenergetics model to estimate metabolic costs and food consumption of each sex. Mature males exhibited lower food consumption, metabolic costs and food conversion efficiencies compared with females. 4. We propose that slower growth in males at the onset of maturity is a result of decreased feeding activity to reduce predation risk. Our finding that SSD in percids is associated with the onset of maturity is supported by laboratory-based observations reported elsewhere, showing that changes in growth rate, consumption and food conversion efficiency were elicited by oestrogen (positive effects) or androgen (negative effects) exposure in P. flavescens and P. fluviatilis. 5. Researchers applying bioenergetic models for comparative studies across populations should use caution in applying bioenergetic models in the absence of information on population sex ratio and potential differences between the sexes in energetic parameters.     

A bioenergetics model for an air-breathing fish, Channa striatus

Food consumption, standard metabolism, and growth of juvenile snakehead, Channa striatus, a cannibalistic and air-breathing fish were measured at 24–26 °C under controlled laboratory condition. Snakehead weighing 3.2–29.5 g were evaluated, and were fed smaller snakehead. Based on our observations, we determined bioenergetics relationships between specific food consumption, metabolic rates, and body weight. These values, along with other published parameter values allowed us to construct a bioenergetics model for snakehead. We then verified our model with growth and food consumption measurements from an independent feeding trial. Predicted fish growth closely matched observed growth. Our model underestimated cumulative food consumption when a constant activity value was used, but consumption estimates improved when we used non-constant activity values (1-5 times of standard metabolism). Predicted fish maintenance ration was 1.7% of body weight per day. Food conversion efficiency was greatest (0.59) when fed 2% body weight daily, but declined when daily consumption exceeded 6% body weight. This model provides a useful approach for assessing food requirements of snakehead under controlled condition. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of food density and temperature on feeding and growth of young inland silversides (Menidia beryllina)

Food consumption and growth rates of 7–28-day-old Menidia beryllina were measured in response to natural ranges of temperature and prey availability. Feeding level, temperature and age all had significant effects on growth rate, although the effect of feeding level explained most of the variance. Feeding level also had a significant effect on gross growth efficiency, but temperature and age did not. Absolute growth rates (mg per day) increased dramatically with temperature, feeding level, and age. Variability in growth was greatest for fish feeding at the lowest feeding level. For a given fish weight, temperature had a positive effect on consumption rate, and maximum consumption ( C _max) of any treatment combination reached 75% body weight per day. Maximum growth rate was estimated at 24.6% body weight per day, and gross growth efficiency reached an estimated maximum of 0.375 at an ingestion rate of 25% body weight per day. Starved larvae lost on average 5.4% body weight per day and larvae required 6.4% body weight food consumption per day for maintenance. Multiple regressions of feeding level, temperature, and age/size on instantaneous growth rates indicated that increases in temperature increased maintenance requirements and required that fish consume a greater proportion of C _max to attain maximum growth. Growth rates decreased with increases in temperature for fish eating a specific weight of food.     

Feeding and digestion by the mussel Mytilus edulis L. (Bivalvia: Mollusca) in mixtures of silt and algal cells at low concentrations

Mussels Mytilus edulis L. from two populations were exposed for 2 days or 2 wk to mixtures of silt and the diatom Phaeodactylum tricomutum Bohlin before measuring rates of feeding, the passage time for food in the gut, absorption efficiency and metabolic rate. Experimental diets were set up to span the range of organic content in seston from the natural habitats (% organic matter by weight: 7–55%), but were less than the total levels of natural seston. Absorption efficiencies were adequately modelled in an exponential relationship to food quality and to gut passage time, although at high proportional silt concentrations metabolic faecal losses led to negative net rates of absorption. Over short-term exposures the scope for growth was a simple function of food quality, and the nutritional quality of the diet was best expressed as organic content per unit volume of particles. Over a period of 2 wk physiological acclimation occurred, across all levels of experimental food quality (which were as low as 10% organic matter by weight), resulting in positive growth potential. Relevant mechanisms of compensation include increased rates of ingestion, increased absorption efficiency and an apparent increase in digestive capacity, estimated here as gut fullness. In experiments in which natural diets are simulated by adding silt to phytoplankton cells, the consequences for net rates of absorption depend on the balance between mean particle size and organic content per unit volume. Calculations show how, in some circumstances, growth may be enhanced by the addition of small silt particles to living phytoplankton cells.