The effect of temperature and mass on routine metabolism in Sarotherodon (Tilapia)mossambicus (Peters)

A reappraisal of oxygen uptake by Sarotherodon mossambicus was undertaken using a continuous flow respirometer. Measurements were obtained over the temperature range 16°C–37°C for fish weighing between 10 g and 150 g. Oxygen uptake was converted to energy equivalents ( Q _ox) using the value 13.68 J mg O₂^–1and the routine metabolic energy expenditure can be described by the equation E =0.0086 t ^{2 0783} M ^{0 652} where E is the energy requirement for routine metabolism expressed in J h^-1, t the temperature in °C and M the mass in g.     

Metabolic utilization of body stores during the early life of whitefish, Coregonus lavaretus L.

Patterns of oxygen consumption, ammonia and urea excretion were monitored during late embryogenesis, i.e. 5 days before mass hatching and 12 days during the free-swimming stage of whitefish larvae, Coregonus lavaretus. Oxygen consumption increased from 1.31 to 2.53 mgO₂ h⁻¹× 10³ eggs⁻¹ at hatching. Fasted, free-swimming larvae showed increasing oxygen consumption to the tenth day after hatching when it reached 5.52 mgO₂h⁻¹× 10³ larvae⁻¹. Ammonia and urea excretion increased during pre-hatching period from 52.1 to 163.2 and 26.8 to 51.4 μgh⁻¹× 10³ eggs⁻¹, respectively. The nitrogen excretion rate increased between the sixth and tenth day of fasting, i.e. for ammonia from 117.7 to 160.9 and for urea from 35.8 to 52.5 μg h⁻¹× 10³ larvae⁻¹. Cumulative data on nitrogen and energy metabolism indicated that during late embryogenesis, and up to the fifth day after hatching, protein dominated in the energy expenditure. During the free swimming stage, the ratio of fat to protein in energy expenditure rose from 0.86 to 1.99. Combined data for several fish species indicated high dependance of oxygen uptake during the hatching period on egg size and temperature.     

Seasonal changes in the body composition of young riverine Atlantic salmon and brown trout

The body composition of protein and fat in Atlantic salmon Salmo salar and brown trout Salmo trutta before and after winter was investigated in a temperate, small river, normally ice covered from the middle of November until the end of March. Fat, protein and specific energy declined greatly in winter but were replenished rapidly in spring. Rates of decline were slower for the smallest fish, which also had the lowest specific content of fat, protein, and energy, while the differences in absolute amounts were greatest for the largest fish. The mean specific fat content was reduced by 45–70% during winter, relative to the pre-winter period (September). Mean daily reductions in specific enegy of the larger size groups of brown trout (3·7 × 10⁻³ kJ g⁻¹ day⁻¹) were almost half of the corresponding values for the largest Atlantic salmon (6·3 × 10⁻³ kJ g⁻¹ day⁻¹) during winter. A minor reduction in protein content was found during winter, with mean reductions of 6–10% in comparison to those in September. During spring the fat content was replenished rapidly, particularly for the smallest salmon fry (a threefold increase from April to June). Fat content in the larger salmon and trout increased by about 1·8 times. Based on estimated metabolic rates, digested energy during wintertime may contribute about two-thirds of the brown trout fry's energy demand. For Atlantic salmon, the corresponding value is about 50%. The winter period put considerable stress on the young salmonids living in lotic environments, in particular for the smallest fry with the lowest energy content before winter and the largest losses during winter. This should make the fry more vulnerable to adverse abiotic and biotic factors.     

The effects of temperature, pH and water hardness on winter starvation of young-of-the-year smallmouth bass, Micropterus dolomieui Lacepede

Year-class strength in northern populations of smallmouth bass is strongly influenced by winter starvation of young-of-the-year. We examined starvation among young bass under both winter and summer light and temperature conditions. During starvation, body condition declines to a specific level and then the fish dies. Body condition at death is a well defined function of body size that remains relatively constant over a wide range of environmental conditions. Starvation rate varies systematically with body size, temperature, pH and water hardness. Available stored energy increases more rapidly with body size than starvation rate. Therefore, lifetime under starvation conditions tends to increase with increasing body size. The Q₁₀ for starvation rate over the temperature range 2.5-8° C is 2.2. Starvation rate increases as pH declines from 7.0-4.9: the rate at pH 4.9 is ∼ 1.25 times the rate at pH 7 Starvation rate decreases as Ca concentration increases from 1 mgl⁻¹ to 80mgl⁻¹: the rate at 80 mg Ca 1⁻¹ is ∼0.80 times the rate at 1 mgl⁻¹.     

Constraints of body size and swimming velocity on the ability of juvenile rainbow trout to endure periods without food

The hypothesis that body size and swimming velocity affect proximate body composition, wet mass and size‐selective mortality of fasted fish was evaluated using small (107 mm mean total length, L _T) and medium (168 mm mean L _T) juvenile rainbow trout Oncorhynchus mykiss that were sedentary or swimming ( c . 1 or 2 body length s⁻¹) and fasted for 147 days. The initial amount of energy reserves in the bodies of fish varied with L _T. Initially having less lipid mass and relatively higher mass‐specific metabolic rates caused small rainbow trout that were sedentary to die of starvation sooner and more frequently than medium‐length fish that were sedentary. Swimming at 2 body length s⁻¹ slightly increased the rate of lipid catabolism relative to 1 body length s⁻¹, but did not increase the occurrence of mortality among medium fish. Death from starvation occurred when fish had <3·2% lipid remaining in their bodies. Juvenile rainbow trout endured long periods without food, but their ability to resist death from starvation was limited by their length and initial lipid reserves.     

Daily ration estimates for yellowfin sole, Limanda aspera (Pallas), based on laboratory consumption and growth

Several estimates of minimal energy requirements for yellowfin sole were made. Energy expenditures of 1.6, 4.1 and 8.3 cal g⁻¹ day⁻¹ were obtained from starvation weight loss, standard metabolism and maintenance ration procedures, respectively, at 6° C. The temperature effect on energy requirement was reflected in the Q ₁₀ values for starvation weight loss (2.0), standard metabolism (6.3) and maintenance ration (6.5).
Both energy intake and weight of food were linearly related to, and good predictors of, laboratory growth. These relationships were used to estimate the food and energy intake necessary for yellowfin sole to achieve a year's growth in the natural environment. Based on a caloric value of 2.0 kcal g⁻¹ of food (herring fillets), yellowfin would require 0.35 to 0.39% body weight day⁻¹ at 3° C to achieve the mean growth rate exhibited in the Bering Sea. To achieve Gulf of Alaska growth rates at 5 to 6° C, yellowfin would require 0.63% body weight day⁻¹. Based on a caloric value of 0.57 kcal g⁻¹ of food (chopped octopus), yellowfin would require 0.83% body weight per day to achieve the Gulf of Alaska growth rate (6° C). These requirements based on the calorific value of herring fillets, which are three to five times higher than previous estimates of daily ration in this species, are probably conservative estimates since many of their prey species have a lower energy content.     

Oxygen consumption in Caridina nilotica (Decapoda: Atyidae) in relation to temperature and size

SUMMARY. The oxygen consumption of shrimps ranging from 1 to 30 mg dry mass was determined at 18, 24 and 30°C using a continuous flow recording respirometer based upon a Clark-type oxygen electrode. Respiration (ascribed to routine metabolism) is described by the power curve: R = a M^b , ( R =μg O₂ h⁻¹, M = mg dry mass), which gives values of a = 1.632, 2.564 and 4.181, and b = 0.800, 0.898, and 0.793, at 18, 24 and 30°C respectively. The single expression, R = 0.008 T ^1.829 M ^0.830 provides a reasonable prediction of respiration as a combined function of shrimp size ( M ) and temperature (T, °C). Using an energy equivalent of 14.14 J mg O₂⁻¹ estimates of the energy requirements ( E , J h⁻¹ 10⁻³) of routine metabolism are given by the expression: E = 0.115 T ^1.829 M ^0.830.
Variability in oxygen consumption values between individuals is discussed and the observations on C. nilotica are compared with other crustacean studies.     

Aspects of energetics of adult walleye pollock, Theragra chalcogramma (Pallas), from Alaska

Body energy partitioning was examined for field-caught, adult walleye pollock; additional laboratory studies were conducted on fish held under controlled temperature conditions at Seward, Alaska.
Average consumption for pollock feeding daily was 0.5% of body weight (3100 cal) at 5°C, resulting in an average growth of 0.12% body weight day⁻¹. These results suggest that large pollock grow at similar rates and have similar food conversion efficiencies to those of Atlantic cod held at similar temperatures.
Resting metabolic rates measured on adult fish were combined with similar data from juveniles to calculate a regression of specific metabolic rate against wet weight: y = 173x⁻⁰²⁶. Maintenance rations amounted to 4.8 cal g⁻¹ day⁻¹ at 5°C, very close to the 0.28% value for juveniles. Estimation of metabolic rate using maintenance ration data resulted in values that were 55% higher than those obtained from oxygen consumption data for unfed fish. Weight loss during starvation was 0.18% of body weight day⁻¹ at 5°C, corresponding roughly to a starvation metabolic rate 50% lower than the resting metabolic rate we report.
We estimate that an adult pollock will lose about 37% of its prespawning body weight and about 46% of its body energy during spawning. These losses result, primarily, from changes in the weight of gonad, liver and somatic tissues as opposed to changes in specific energy content of those tissues.     

Energy and ration requirements of juvenile Pacific halibut (Hippoglossus stenolepis) based on energy consumption and growth rates

Growth of captive juvenile Pacific halibut was linearly related to energy consumption (J g⁻¹ day⁻¹) at 4°C by the following equation: growth (% body weight (b.w.) day⁻¹)=0–007 (consumption J g⁻¹ day⁻¹)– 0.192; r² =0.81. Weight gain was independent of size for fish between 9 and 7000 g when growth was expressed as a function of consumption in J g⁻¹ day⁻¹. Maintenance ration determined in feeding–growth experiments averaged 27.4 J g⁻¹ day⁻¹ at 4–0°C. Small halibut ate significantly more food than large fish. Single meals following 2 day fasts averaged 4.1% b.w. for halibut under 100 g, 1.72% b.w. for 1.2 kg fish and 1.1% B.W. for 6.8 kg fish. Both large and small size categories of halibut tended to evacuate their meal in about 3 days even though small fish ate relatively larger meals. Minimum estimates for daily ration to achieve growth rates observed in the Gulf of Alaska were approximately 0.5 to 2.4% b.w. day⁻¹ depending on fish size and whether northern shrimp or yellowfin sole were their prey.     

Estimation of the starvation losses of nitrogen and energy in the rainbow trout (Oncorhynchus mykiss) with special regard to protein and energy maintenance requirements

Literature data are analysed regarding losses of body substances occurring during a period of food deprivation in rainbow trout ( Oncorhynchus mykiss ). Nitrogen (protein) and energy losses show a distinct dependence on fish mass (FM [g]) and water temperature (T [°C]). Several regression models for this relationship were compared with best testing estimates as follows:
Nitrogen loss [mg N 2 fish⁻¹ 2 d⁻¹] = 0.0658 e^(1.037) 2 FM^0.739
( n = 49, 9–20°C, 5–400g fish mass, P < 0.001, B = 0.826)
Nitrogen-corrected energy loss [J 2 fish⁻¹ 2 d⁻¹] = 22.09 e^(1.034) 2 FM^0.833
( n = 63, 9–25°C, 8–400 g fish mass, P < 0.001, B = 0.887).
For nitrogen loss as well as for nitrogen-corrected energy loss, the metabolic rate shows a progressive increase with rising water temperature. The temperature coefficient increases in magnitude as temperature increases. The introduction of a general common exponent (0.8 instead of 0.739 for nitrogen loss and 0.833 for energy loss) for fish mass decreases the precision of the estimate. The equations could serve as a base for estimating net protein and net energy maintenance requirements of rainbow trout. Possible limitations, caused by uncertainities in estimating the elevated metabolic rate by food intake and ingestion, are discussed.     

A new type of metabolism chamber for the determination of active and postprandial metabolism offish, and consideration of results for coregonid and salmon juveniles

The optomotor reaction of juvenile Coregonus schinzipalea Val. et Cuv. and Salmo salar L. was utilized to develop a circular tube metabolism chamber to measure oxygen consumption and ammonia excretion as a function of swimming speed. The metabolism chamber with a constant water flow assured the maintenance of stable conditions. The unidirectional movement of fish was measured in a circular tube with a single narrowing. The relationships between the swimming speed and oxygen consumption or ammonia excretion described by exponential equations allowed the extrapolation towards the standard metabolism, i.e., zero swimming speed. For a juvenile coregonid (0.1–0.15 g individual weight, 2.6–2.8 cm total length) standard metabolism at 14° C was estimated as 0.65 mg0₂ g⁻¹ h⁻¹ and 17.3 μg N(NH₃)g⁻¹ h⁻¹, whereas for juvenile salmon (136mg individual weight) respective values at 22° C were 0.047mg0₂g⁻¹h⁻¹ and 0.61 μg N(NH₃)g⁻¹ h⁻¹. The feeding test with juvenile salmon was also performed in this circular chamber, and in both energy and nitrogen budgets after a meal the partitioning could be precisely attributed to standard metabolism, active metabolism and specific dynamic action (in the case of oxygen consumption) or postprandial nitrogen increase.
The new metabolism chamber allowed the relationship between metabolism and swimming velocity of juvenile fish with developed rheotactic response. It could be used with adult fish for similar purposes.     

Elevated oxygen uptake and high rates of nitrogen excretion in early life stages of the cobia Rachycentron canadum (L.), a fast-growing subtropical fish

Physiological energetics of cobia Rachycentron canadum were quantified for 18 to 82 days post-hatch (dph) hatchery-reared juveniles to better understand energy transformation and its implications in growth and survival. Mean oxygen consumption rates ( ; mg O₂ h⁻¹) of fish fed ad libitum and fish that were starved significantly increased with increasing wet mass (M; g), = 1·4291 M ^0·8119 and = 1·1784 M ^0·7833, respectively, with a significant reduction in mean metabolic rates of starved fish (19 to 27% specific dynamic action; SDA). Total ammonia nitrogen excretion rates ( A _MM, μmol h⁻¹) also scaled with M and significantly decreased after starvation. Mean mass-specific A _MM and urea excretion rates are the highest reported in the literature, with urea accounting for approximately half the total nitrogen excretion measured in both fed and starved fish. Relatively high energetic rates may allow cobia to develop rapidly into pre-juveniles and be less susceptible to predation and starvation at a comparatively early age.     

Inter‐individual differences in rates of routine energy loss and growth in young‐of‐the‐year juvenile Atlantic cod

Inter‐individual differences in rates of routine (non‐feeding) metabolism and growth were evaluated in young‐of‐the‐year (YOY) juvenile Atlantic cod Gadus morhua . Rates of O₂ consumption, CO₂ production and ammonia (TAN) excretion were measured in 64, 25–43 mm standard length ( L _S) YOY growing at different rates (0·27–0·47 mm day⁻¹) in a common rearing tank. Parameter rates ( y ) increased allometrically ( y = a·M^b ) with increasing body mass ( M ) with b ‐values for O₂ production, CO₂ consumption and TAN excretion equal to 0·81, 0·89 and 0·56, respectively. In some cases, residuals from these regressions were significantly negatively correlated to fish growth rate. In no cases did residuals of parameter rates increase with increasing growth rate. These data suggest that, during unfed periods, relatively fast‐growing fish were more metabolically efficient than slower‐growing fish from the same cohort. The fish condition factor, derived from     , also significantly decreased with increasing growth rate. Results indicated differences in both the rates of routine energy loss and the patterns of growth allocation among YOY Atlantic cod. Since these physiological attributes were positively correlated with growth rate, they may be indicative of 'survivors' in field populations.     

Exoprotease activity of Leuconostoc oenos in stress conditions

Exoprotease activity during 48 h of total energy and nutrient starvation was examined in Leuconostoc oenos X₂L isolated from wine. Starved cells after 2 h of incubation at 30 °C in citrate buffer, 0.05 mmol 1⁻¹ pH 5, showed greater extracellular proteolytic activity than at the onset of starvation. In the presence of 60 mg l⁻¹ SO₂ and 8% or 12% ethanol, the proteolytic activity was higher ; 10 mmol l⁻¹ Ca²⁺ and Mg²⁺ produced an increase in protease activity during starvation. Glucose and 2-deoxyglucose (2-DOG) were found to repress synthesis by 80% and 100%, respectively. Cyclic adenosine 3'-5'-phosphate increased the exoprotease activity and reverted the repression by glucose and 2-DOG. De novo synthesis of proteins was required for the exoprotease activity by cells submitted to stress conditions. The absence of protease activity in the supernatant fluids from chloramphenicol-treated cells indicated that the activity is a result of deliberate release and not of passive cell lysis.     

Utilization of several plant proteins by gibel carp (Carassius auratus gibelio)

Six isonitrogenous (gross protein content 35%) and isoenergetic (gross energy content 17 kJ g⁻¹) diets were formulated to investigate the effects of inclusion of plant proteins on the gibel carp ( Carassius auratus gibelio L.). The plant proteins tested were: soybean cake (SBC), potato protein concentrate (PPC), peanut cake (PNC), cottonseed cake (CSC) and rapeseed cake (RSC). Fish meal (FM) was used as control. In each diet, 27% of the protein was supplied by fish meal, and the rest supplied by the plant protein tested. Each diet was fed to three groups of gibel carp for 8 weeks in a recirculation system. Specific growth rate (SGR) in fish fed the control diet was significantly higher than those in the other groups, and SGR in fish fed the PPC was significantly lower than in fish fed other plant proteins. There was no significant difference in SGR among the other groups. Feeding rates were ranked in the order: RSC > CSC > FM > PNC > SBC > PPC. Conversion efficiency was highest in groups fed FM, SBC and PNC, followed by groups fed CSC and RSC, and was lowest in the group fed PPC. The fish fed PPC showed lower protein retention than those fed FM and SBC. FM showed highest energy retention while PPC showed lowest. There was no significant relationship between SGR and intake of digestible protein (g g⁻¹ day⁻¹), digestible lysine (g g⁻¹ day⁻¹), digestible methionine (g g⁻¹ day⁻¹) or digestible total essential amino acids (g g⁻¹ day⁻¹), suggesting that the differences in SGR could not alone account for any of these variables.     

Temporal patterns of milk production in Antarctic fur seals (Arctocephalus gazella)

The timing of milk production in Antarctic fur seals was studied at Bird Island, South Georgia. Like all lactating otariid seals (Pinnipedia: Otariidae), Antarctic fur seal females alternate between short nursing periods ashore and regular foraging trips to sea. Females do not necessarily return to the colony with full mammae, which indicates that mammary volume capacity is unlikely to limit foraging trip duration. Upon arrival at the colony, milk fat (r²= 0.33, P < 0.04) and protein (r²= 0.60, P < 0.002) content were positively correlated to the time spent at sea. A similar trend was observed in the milk produced on land. The rate of milk energy production was much lower at sea (5.02 ± 0.05 MJ day^-1) than on land (23.66 ± 4.4 MJ^-1 day^-1). The rate of milk energy production during the foraging trip was negatively correlated to the time spent at sea (r²= 0.29, P < 0.05), whereas the rate of milk energy production on land was positively correlated (r²= 0.61, P < 0.001) to the duration of the preceding foraging trip. The total amount of milk energy delivered to the pup during each twoday nursing period was positively correlated (r²= 0.60, P < 0.002) to the duration of the previous foraging trip. The overall rate of milk energy delivery, however, was independent of foraging trip duration. This accords with previous observations that the growth rates of Antarctic fur seal pups are unaffected by maternal foraging trip duration patterns.     

Energy metabolism in eggs and larvae of the Senegal sole

Oxygen consumption in Solea senegalensis increased during the egg stage reaching values close to 4 nmol O₂ ind⁻¹ at hatching. After hatching, larval oxygen consumption continued to increase, reaching a maximum rate of 9.97⁻¹±87 nmol O₂ ind⁻¹ h⁻¹ 2 days after the opening of the mouth. Body nitrogen content decreased mainly after exhaustion of yolk reserves. Carbon content decreased during the whole endogenous feeding phase, although it decreased twice as quickly after yolk-sac absorption. The free amino acid (FAA) depletion rate was higher during egg development and the yolk-sac period. Complete yolk absorption coincided with the consumption of the 90% of initial FAA content in the eggs and the remaining FAA were consumed at a lower rate. Based on stoichiometrical calculations, FAA appears to be the most important energy substrate during the egg stage (86%) in the Senegal sole. During the period from hatching to the mouth opening, contributions of FAA and lipids as metabolic fuels were similar (41 and 47%, respectively). The decrease in larval protein content during starvation indicates that amino acids from body protein are used as energy substrates under food deprivation.     

Nutritional estimate of populations of some wild free-ranging African ungulates in grassland (Nechisar national park, Ethiopia) in dry season

The amount and nutritive value of forage plants, diet composition, digestibility of dry matter and nutrients were recorded for zebra. Grant's gazelle, Swayne's hartebeest and hippopotamus in November-December 1991 Besides, daily egest of feces, the level of food and nutrient consumption, energy and protein requirements were recorded for zebra and Grant's gazelle The digestibility of pasture forage was determined as a ratio of lignin concentration in food to the concentration m feces (lignin tracer technique), a daily intake was calculated on the basis of the daily feces egest Protein percentage m the diet of zebra and hartebeest consuming dry parts of grasses did not exceed 5% Gazelle diet consists of green parts of plants and included 18% of protein The digestibility of dry matter in nonruminants (zebra, hippopotamus) was 40-45%, in hartebeest - 50%, in gazelle - 60% Due to the abundance of dry grasses (3 7 ton ha^-1) the daily food consumption of zebra was high - 7 2 kg ind^-1 (dry weight), the metabolizable energy intake (ME) being 51 MJ Adult gazelles consumed 15-25 kg ind^-1 of food and 14-24 MJ of ME The energy requirements of adult males and non-lactating females of zebras and gazelles (48 and 13 MJ respectively) were met, the energy balance berig negative for lactating animals The daily protein requirement was not met in zebra (392-704 g md^-1 vs 134 g ind^-1 of intake) and in lactating gazelles (250 g ind^-1 vs 197 g md^-1) Non-lactating gazelles consume sufficient amount of both energy and protein due to the high feeding selectivity of the species and thanks to the abundance of burnt areas with young green after-grass m the dry period     

The effects of long-term food deprivation on respiration and haematology of the neotropical fish Hoplias malabaricus

Growth of adult traíras Hoplias malabaricus ceased and body mass ( M ) decreased during starvation periods of 30, 60, 90, 150, 180 and 240 days. Hepatic reserves were mobilized in fish starved for 30 days, but liver mass of fish starved for longer periods was not significantly different from those starved for 30 days. Perivisceral fat bodies were consumed gradually, being completely exhausted after 240 days of food deprivation. Length of starvation was associated with a significant decrease in the oxygen uptake ( V o₂). In spite of this reduction, the respiratory frequency ( f _R) was kept nearly constant during the starvation periods. The haematocrit and the number of red blood cells decreased after 150 and 240 days of starvation, respectively. These parameters did not recover after refeeding (after 90 and 240 days of starvation). This hypometabolic state in response to food deprivation contributed to energy conservation during these periods. Traíras can survive food deprivation for periods of up to 180 days without reductions in metabolism and when they do become hypometabolic, normal metabolic rates are rapidly restored upon refeeding.     

Compensatory growth and reduced maturation in second sea winter farmed Atlantic salmon following starvation in February and March

Starvation of second sea winter farmed Atlantic salmon through February and March reduced body weight by 0.10% day⁻¹ or 6.0% during the starvation period, whereas fed fish increased body weight by 0.10 day⁻¹ or 5.9%. When fed again during 41 days in April and May, the starved group increased weight by 22.7% (0.55% day⁻¹) compared with a 11.4% (0.28% day⁻¹) gain in the unrestricted control. Ultrasound determination of sex and maturity in late May showed that the incidence of maturation was reduced by 48% among females and 32% among males in the starved group, compared with the unrestricted group.