Development of bile salt-dependent lipase in larval turbot

Pancreatic bile salt-dependent lipase (BSDL) was present with 0·5 μg BSDL larva⁻¹ from hatching in turbot larvae. The enzyme content increased during the yolk sac phase to 1·1 μg BSDL larva⁻¹. This suggests that larval turbot are able to digest lipids from the start of exogenous feeding. The BSDL synthesis was stimulated first by food about 5 days after the onset of first feeding. The content per larva increased exponentially in fed larvae to 20 μg BSDL larva⁻¹ on day 23 after hatching and decreased in starved larvae. In contrast, the specific content decreased during the first feeding phase, meaning that smaller larvae had a higher content of enzyme related to their biomass than did bigger larvae.     

The content of prostaglandins and their precursors in Mortierella and Cunninghamella species

Five strains of filamentous fungi belonging to the genera Mortierella and Cunninghamella were examined for the content of dihomo-γ-linolenic, arachidonic, eicosapentaenoic acids and prostaglandins (type E₂ and F _2α). Prostaglandins were detected using an ELISA method in mycelia of all tested strains (range 50–4800 ng g⁻¹ of PGE₂ and 6–30 ng g⁻¹ of PG F _2α). Several micro-organisms also produced prostaglandins in the culture medium (2·2–137·6 μg l⁻¹ for PGE₂ and 0·4–7·8 μg l⁻¹ for PG F _2α).     

Antioxidant status of anoxia-tolerant and -intolerant plant species under anoxia and reaeration

The redox potential of the cell, as well as the antioxidant status of the tissue, are considered to be important regulatory constituents in an adaptive response in plants. Here the involvement of active antioxidants ascorbic acid (AA), reduced glutathione (GSH) and α - and β -tocopherols in reactive oxygen species scavenging, and the effect of anoxic stress on their reduction state were studied in 4 anoxia-tolerant and -intolerant plant species: Iris germanica L., Iris pseudacorus L., wheat ( Triticum aestivum L. cv. Leningradka) and rice ( Oryza sativa L. cv. VNIIR). The initial antioxidant content (both AA and GSH) was higher in the rhizomes of the more anoxia-tolerant Iris spp., as compared with that of the roots of the cereals. The predominant form of ascorbate was dehydroascorbic acid (DHA) in the cereals and AA in the Iris spp. Imposition of anoxia with subsequent reoxygenation resulted in an overall depletion of the reduced forms of antioxidants. No concurrent increase in oxidised forms (DHA and conjugated glutathione) was observed in anoxic samples. α -tocopherol content in Iris spp. was in the range 1–2 μg g⁻¹ fresh weight, while β -tocopherol content was higher in the anoxia-intolerant I. germanica (7.2 μg g⁻¹ fresh weight) as compared with the tolerant I. pseudacorus (1.5 μg g⁻¹ fresh weight). In I. pseudacorus , a significant decrease in α - and β -tocopherol levels was observed only after long-term (45 days) anoxia. The results suggested exclusion of AA and GSH from the redox cycling under prolonged anoxia, and a concomitant decrease in the redox state, as well as an anoxia-induced depletion of α - and β -tocopherols.     

Oxygen uptake in developing eggs and larvae of the cod, Gadus morhua L.

Unfertilised cod eggs showed a mean oxygen uptake rate at 5°C of 0.089 μl O₂, dry wt.⁻¹ h⁻¹; this gradually rose to 0.768 μl O₂ mg dry wt.⁻¹ h⁻¹ in eggs about to hatch. From hatching to complete yolk absorption larvae respired at 1.6 μl O₂, mg dry wt.⁻¹ h⁻¹. During starvation following yolk absorption, uptake fell significantly to 1.1 μl O₂, mg dry ⁻¹ h⁻¹. Much of this decrease in oxygen consumption was shown to be caused by reduction in activity. Loss of weight during the embryo and larval phases could not easily be reconciled with total oxygen consumption; it is suggested that cod embryos and larvae may not rely solely upon endogenous energy reserves during development.     

Oxygen consumption by eggs and larvae of striped mullet, Mugil cephalus, in relation to development, salinity and temperature

Oxygen consumption rates during embryonic and the first 38 days of larval development of the striped mullet were measured at 24° C by differential respirometry. Measurements were obtained at the blastula, gastrula and four embryonic stages, and at the yolk-sac, preflexion, flexion and post-flexion larval stages.
Oxygen uptake rates of eggs increased linearly from 0.024 μl O₂ per egg h^-1 (0·323 μl O₂ mg^-1 dry wt h^-1) by blastulae to 0·177 μlO₂ per egg h^-1 (2·516 μlO₂mg ¹dry wth^-1) by embryos prior to hatching. Respiration rates did not vary significantly among four salinities (20,25, 30, 35%₀).
Larval oxygen consumption increased in a curvilinear manner from 0·243 μl O₂ per larva h^-1 shortly after hatching to 18·880 μl O₂ per larva h^-1 on day 38. Oxygen consumption varied in direct proportion to dry weight. Mass-specific oxygen consumption rates of preflexion, flexion, and postflexion larvae did not change with age (10·838 μl O₂ mg ¹dry wt h^-1).
Larval oxygen consumption rates did not vary significantly among salinities 10–35%. Acute temperature increases elicited significant increases in oxygen consumption, these being relatively greater in yolk-sac larvae ( Q₁₀ = 2·75) than in postflexion larvae ( Q₁₀ = 1·40).     

The respiration of young coho Oncorhynchus kisutch at gradually declining oxygen levels and during recovery from oxygen deprivation

The respiration of coho salmon, Oncorhynchus kisutch , weighing between 15 and 50 g was measured at gradually declining oxygen levels and at temperatures ranging between 14 and 17°C. The maximum and minimum oxygen concentrations tested were 250 and 40 μmol L⁻¹, respectively. Respiration rates were measured for 1 h periods before oxygen concentration was lowered by 12.5 or 25.0 μmol oxygen L⁻¹. At the end of these endurance tests the oxygen level was returned to normoxic conditions and respiration rates were determined for the recovery period. Under normoxic conditions (> 200 μmol L⁻¹) the respiration of coho levelled around 5.1 μmol g⁻¹ wet weight h⁻¹. At intermediate levels between 150 and 200 μmol oxygen L⁻¹, the average rate increased to 5.8 μmol g⁻¹ h⁻¹, which could be attributed to higher spontaneous activity of the test animals. At low oxygen levels (< 150 μmol⁻¹) average respiration rates dropped to values between 5.5 and 5.7 μmol g⁻¹ h⁻¹, reaching a minimum of 3.8 μmol g⁻¹ h⁻¹ at oxygen levels below 50 μmol L^μ. First mortality was observed in this range. After exposure to reduced oxygen levels the fish maintained a higher respiration rate when again exposed to normoxic oxygen levels above 200 μmol L⁻¹. Increased respiration rates were observed for a recovery period of 6 h.     

Endogenous levels of polyamines and abscisic acid in pepper fruits during growth and ripening

The levels of polyamines (PA) and abscisic acid (ABA) in the pericarp of California variety pepper fruit ( Capsicum annuum L.) were analyzed during development and ripening. Putrescine level was 2.75 μmol g⁻¹ fresh weight 7 days after fruit set and fell during the exponential stage of growth to 1.05 μmol g⁻¹ fresh weight. During the second growth stage. PA and ABA levels remained stable and fell sharply at the beginning of maturation. The levels of spermidine and spermine decreased throughout fruit development and maturation from 0.61 to 0.05 and 0.31 to 0.02 μmol g⁻¹ fresh weight, respectively, but no changes were associated with the onset of maturation. ABA levels remained high (0.70-0.80 μg g⁻¹ fresh weight) during the stages of fruit growth and fell at the beginning of maturation to 0.12 μg g⁻¹ fresh weight, before rising again during the last stages of maturation and senescence. The decrease in putrescine and ABA levels and the subsequent increase in the latter may be responsible for controlling the processes of ripening in pepper fruit.     

Oxygen consumption in Oreochromis niloticus (L.) in relation to development, salinity, temperature and time of day

Oxygen consumption of Oreochromis niloticus at different stages of development was studied in relation to salinity, temperature and time of day, using a Warburg apparatus. The oxygen consumption of newly hatched (0–14 h) larvae was 3.40 μl O₂ larva⁻¹ h⁻¹, of older yolk sac larvae 10.09 μl O₂ larva⁻¹ h⁻¹, and of one-month-old fry 32.99 μl O₂ larva⁻¹ h⁻¹. The QO₂ values showed a decrease with development and growth, ranging from 21.2–26.0 μl O₂ mg⁻¹ h⁻¹ in newly hatched larvae to 2.97 μl mg⁻¹ h⁻¹ in one-month-old fry. Changes in oxygen consumption occurred with salinity, the highest being at 17%o. Active larvae (12-24 mm T.L.) showed a doubling of consumption with a 10° C rise in temperature, and their Q₁₀ factor increased from 2.25 to 3.43 with increasing size. Day-old yolk-sac larvae, late yolk-sac larvae (5 days old) and fry of 12 14 mm length all showed a depression in oxygen consumption at midnight followed by a dawn rise.     

The effects of water hardness upon the uptake, accumulation and excretion of zinc in the brown trout, Salmo trutta L.

The effects of water hardness (9 and 220 mgl⁻¹ as CaCO₃) upon zinc exchange in brown trout exposed to 0.77 μmol Zn 1⁻¹ have been investigated using artificial soft water (<49.9 μmol Ca ^l-1, <40.1 μmol Mg 1⁻¹) and mains hard water (1671.7 μmol Ca 1⁻¹, 493.6 μmol Mg 1⁻¹) of known composition. Both hard and soft water-adapted fish exhibited a bimodal pattern of net zinc influx. Net zinc influxes during both fast and slow uptake phases were significantly greater ( P <0.001) in soft (82.9 and 6.2 μmol Zn 100 g⁻¹ h⁻¹) than in hard water (46.3 and 2.4 μmol Zn 100 g h⁻¹). Zinc efflux (- 0.2 μmol Zn 100 g⁻¹ h⁻¹) was enhanced only in hard water during the slow net influx phase.
Brown trout exposed to zinc in hard water and placed in metal-free media exhibited a greater net efflux (- 25.6 μmol Zn 100 g⁻¹ h⁻¹) of the metal than did fish in soft water (-4.2 μmol Zn 100 g⁻¹ h⁻¹) treated in the same manner. Tissue ⁶⁵Zn activities reflected both the differences in uptake and excretion rates of the metal between hard and soft water fish. During zinc exposure (0.77 μmol Zn 1⁻¹) high water hardness reduced tissue burdens of the metal by reducing net branchial influx, and enhancing efflux of the metal in hard water fish.     

The effect of light intensity and spectrum on the incidence of first feeding by larval haddock

Under full–spectrum white light, feeding success of haddock Melanogrammus aeglefinus first feeding larvae, as measured both by proportion of larvae feeding and mean prey consumed, peaked at 1·7-18 μmol s^-1 m^-2. Feeding was significantly reduced at lower and higher intensities. A similar result was observed for larvae feeding under blue (470 nm) light, with significantly greater feeding success at intermediate light intensity (1·8 μmol s^-1 m^-2). When different light qualities were compared, larvae had significantly greater feeding success when exposed to blue (470 nm) light than either full-spectrum white or green (530 nm) light. Haddock larvae were capable of prey capture under all light treatments tested, indicating a necessary degree of adaptive flexibility in feeding response. The results are consistent with predisposition of haddock larvae to optimal feeding in a visual environment comparable with open ocean nursery grounds. Information on the impact of light on haddock first feeding can be incorporated into models of larval growth, survival, year-class strength and recruitment, and assist in developing husbandry protocols to maximize larval survival in aquaculture.     

Anti-bacterial activity of synthetic N-heterocyclic oxidizing compounds

Synthetic chlorochromate derivatives of pyridine and quinoline were active in vitro against type cultures of Escherichia coli (ATCC 128), Staphylococcus aureus (ATCC 14775), Pseudomonas aeruginosa (ATCC 10145) and Bacillus subtilis (NCTC 8236). The minimum inhibitory concentrations (MIC) were 125–250 μg ml⁻¹ and 250–500 μg ml⁻¹ for pyridinium chlorochromate and quinolinium chlorochromate, respectively. An established derivative of quinoline (Perfloxacin) had an MIC of 125–250 μg ml⁻¹. The extinction time for 10⁵ cfu in broth was 90 min for pyridinium chlorochromate and 120 min for quinolinium chlorochromate, except for B. subtilis which survived up to about 180 min and 360 min. A combination of the two compounds produced an antagonistic effect. The 50% lethal dose (LD₅₀ toxicity) in mice was estimated at 76 μg g⁻¹ and 33 μg g⁻¹ body weight for the quinolinium and pyridinium chlorochromates. The compounds also exhibited some potential for suppressing a simulated staphylococcal infection in mice at the dosage levels of ca 22 μg g⁻¹ for pyridinium chlorochromate and 45 μg g⁻¹ for quinolinium chlorochromate.     

Effects of cadmium chloride on the development of rainbow trout Oncorhynchus mykiss early life stages

The sub-chronic (28–56 days) effects of exposure to low concentrations of cadmium (Cd; 0·05, 0·25, 0·50 and 2·50 μg l⁻¹) shortly following fertilization on embryos, larvae and juvenile rainbow trout Oncorhynchus mykiss were examined. Premature hatching occurred at lower concentrations (0·05 and 0·25 μg l⁻¹ Cd), however, delayed hatching was seen in the 2·50 μg l⁻¹ Cd group, with >90% of hatching occurring on the last day of the hatching period. Larval growth was negatively affected by Cd exposure in a concentration-dependent manner. Larvae exposed to 2·50 μg l⁻¹ Cd were 13·9 ± 0·8% shorter in total length ( L _T) and weighed 22·4 ± 3·5% (mean ± s . e .) less than controls at the end of the exposure period. Plasma sex steroid concentrations (oestradiol in juvenile females and 11-ketotestosterone in juvenile males) were elevated (four- to 10-fold over controls) in exposed fish in both males and females, following 28 days of exposure to 0·05, 0·25 and 0·50 μg l⁻¹ Cd, respectively. These results suggest that environmentally realistic concentrations (in the μg l⁻¹ range) of Cd can affect the development of O. mykiss impacting embryos, larvae and juvenile fish.     

Ascorbate concentration in fish ontogeny

The ontogenetic trend of ascorbate has been quantified in three freshwater fishes: roach ( Rutilus rutilus ), whitefish ( Coregonus lavaretus ) and Arctic charr ( Salvelinus alpinus ). Total ascorbate (reduced and oxidized) declined from 150 to μg g⁻¹ as newly hatched larvae grew to become several-months-old juveniles. Declining total ascorbate with increasing size of metamorphosing fish could not be reversed by feeding on brine shrimp, Artemia salina nauplii, zooplanktonic food containing > 74μg g⁻¹ total ascorbate. The proportion of reduced ascorbate in total ascorbate increases with fish size/age. The physiological mechanism of the changes in transferable ascorbate forms remains unknown, but high dehydroascorbate concentrations suggest high vulnerability of larval fish to oxidation stress. This is the first report on quantity of vitamin C retained in actively-feeding larval and juvenile fish. The efficiency of ascorbate transfer from zooplankters to larval fish amounted to 5–20%. The ecological significance of larval fish feeding on various zooplankters and/or phytoplankton may reflect a trend toward maximum transfer of this vitamin in freshwater food webs.     

Early development of milkfish: effects of salinity on embryonic and larval metabolism, yolk absorption and growth

During embryogenesis of Chanos chanos , more than half of the yolk was consumed and the majority of it was converted into larval tissue. Salinity affected both yolk absorption and embryonic and larval growth. Larvae hatched in 20% had larger yolk reserves but were smaller and grew more slowly than larvae in 35 and 50%. Larvae hatched in 35 and 50% had equal amounts of yolk but those from 35% were larger. Oxygen consumption rates increased during development (from 0.06 ± 0.01 μl O₂ egg^–1 h^–1 by blastulae to 0.37 ± 0-01 μl O₂ egg^–1 h^–1 by prehatch embryos and 0–43 ± 0–03 μl O₂ larva ^–1 h ^–1 by newly-hatched larvae) and were significantly affected by salinity. Eggs and yolk-sac larvae incubated in 35% consumed more oxygen than those in the low and high salinities. Salinity affected both the rate and pattern of yolk utilization but salinity-related differences in metabolism, yolk absorption, and growth were not related directly to the osmotic gradient. Low salinity retarded yolk absorption while high salinity reduced yolk utilization efficiencies. Differences in oxygen consumption rates were probably related to variations in the relative amounts of metabolically active embryonic and larval tissue and/or higher activity levels rather than differential osmoregulatory costs. 35% is probably the most suitable salinity for incubation and larval rearing of milkfish.     

Effects of development, temperature and salinity on metabolism in eggs and yolk-sac larvae of milkfish, Chanos chanos (Forsskål)

Oxygen uptake rates and yolk-inclusive dry weiGhts were measured during the egg and yolk-sac larval stages of milkfish, Chanos chanos (Forsskal). Oxygen uptake by eggs and yolk-sac larvae was measured to assess the effects of four salinities (20,25,30,35 ppt) at 28°C. The effects of three temperatures (23,28,33°C) on oxygen uptake by yolk-sac larvae were determined at a salinity of 35 ppt. Dry weights were measured throughout embryonic development at 28°C and the yolk-sac stage at 23.28 and 33°C.
Oxygen uptake rates of eggs increased more than fivefold during embryogenesis (0.07±0.03 to 0.40 ± 03 μl O₂ egg ⁻¹ h ⁻¹;blastula to prehatch stage). Larval oxygen uptake did not change with age but was affected by rearing temperature (0.33 ± 0.08, 0.44 ± 0.07 and 0.63 ± 0.13 μl O₂ larva ⁻¹ h⁻¹ at 23, 28 and 33°C, respectively; Q₁₀= 1.93). Acute temperature changes from 28 to 33°C caused significant increases in oxygen uptake by embryos (Q ₁₀= 1.69–3.58) and yolk-sac larvae (Q ₁₀=2.55). Salinity did not affect metabolic rates.
Dry weight of eggs incubated at 28°C decreased 13% from fertilization to hatching. Incubation temperatures from 23–33°C did not affect dry weights at hatching. Rearing temperatures significantly affected the rate of larval yolk absorption (Q ₁₀= 2.25).     

Species of Anguilla as indicators of mercury in the coastal rivers and lakes of Victoria, Australia

Mercury concentrations in the axial muscle tissue of most (243) of the 254 Anguilla australis and most (20) of the 27 A. reinhardtii collected from 30 sites in coastal rivers and lakes in Victoria, Australia, during 1975–78 were well below the Australian statutory health limit (0.5 μg g⁻¹ wet weight). For A. australis the mean mercury concentration was 0.17 μg g⁻¹ (±0.16 s.d. , range 0.01–1.60 μg g⁻¹); for A. reinhardtii the values were 0.37 ± 0.23 μg g⁻¹ (range 0.12–1.10 μg g⁻¹). Statistical analyses showed that variation in mercury concentration due to total length accounted for only 13% of the total variation in A. australis and 2% in A. reinhardtii whereas locality accounted for 54 and 68%, respectively. Both species are thus considered suitable as indicators of mercury pollution.     

Ethylene synthesis and growth in embryogenic tissue of Norway spruce: Effects of oxygen, 1-aminocyclopropane-1-carboxylic acid, benzyladenine and 2,4-dichlorophenoxyacetic acid

Ethylene production from an embryogenic culture of Norway spruce ( Picea abies L.) was generally low. ca 2.5 nl g⁻¹ h⁻¹, whereas 1-aminocyclopropane-1 -carboxylic acid (ACC) concentration was high, fluctuating between 50 and 500 nmol g⁻¹ during the 11-day incubation period. Hypoxia (2.5 and 5 kPa O₂) rapidly inhibited ethylene production without subsequent accumulation of ACC. Exogenous ACC (1, 10 and 100 μ M ) did not increase ethylene production, but the highest concentrations inhibited tissue growth. Ethylene (7 μl I⁻¹) did not inhibit growth either when supplied as ethephon in the medium or in a continuous flow system. Benzyladenine (BA) had little effect on ethylene production, although it was necessary for sustaining the ACC level. Omission of 2.4-dichloro-phenoxyacetic acid (2.4-D) from the medium caused ethylene production to increase from about 2.5 to 7 nl g⁻¹ h⁻¹ within the 11-day incubation period. Although 2.4-D did not specifically alter the endogenous level of ACC, the lowest ACC level, 33 nmol g⁻¹, was observed in tissue treated with 2.4-D (22.5 μ M ) and no BA for 11 days. Data from this treatment were used to estimate the kinetic constants for ACC oxidase, the apparent K_m was 50 μ M and V_max 2.7 nl g⁻¹ h⁻¹. Growth of the tissue was strongly inhibited by 2.4-D in the absence of BA, but weakly in the presence of BA (4.4 μ M ). The results suggest that ethylene or ACC may be involved in the induction of embryogenic tissue and in the early stages of embryo maturation.     

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.     

Transgenerational marking of freshwater fishes with enriched stable isotopes: a tool for fisheries management and research

A promising new method of marking larval freshwater fishes with enriched stable isotopes by means of injecting the maternal parent with the marking agent was investigated. The ¹³⁸Ba:¹³⁷Ba ratios in the otoliths of larval golden perch Macquaria ambigua were compared to determine the effect of injecting female broodstock with different dosages of enriched ¹³⁷Ba at various times before spawning. There was 100% mark success in the progeny of fish injected with 20 μg g⁻¹ of enriched ¹³⁷Ba 24 h before inducing spawning with hormones and 40 μg g⁻¹ administered at the same time as inducement of spawning. Injection of 40 μg g⁻¹ enriched ¹³⁷Ba 21 days before spawning resulted in only 81% mark success and suggests rapid elimination of barium in M. ambigua . Injection with enriched ¹³⁷Ba did not significantly affect the fertilization rate, number of fertilized eggs or hatching rate compared with long-term hatchery records. These results suggest that transgenerational marking is an effective and affordable means of mass-marking larval fishes. Thousands of larval fishes can be permanently marked with a unique artificial isotopic mark via a single injection into the maternal parent, thus avoiding the handling of individual fishes or having to deal with chemical baths. Because no single mark or tagging method is suitable for all situations, transgenerational marking with enriched stable isotopes provides another method for researchers and managers to discriminate both hatchery-reared and wild fishes.     

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.