bluuebunny/crossref_metadata_2025_split huggingface dataset:
The immune system of juvenile thick‐lipped grey mullet, Chelon labrosus Risso: antibody responses to soluble protein antigens
Authors: Mughal M. S. , Manning M. J. 
Published: January 2006

Juvenile thick‐lipped grey mullet, Chelon labrosus, believed to be about 6–7 months old, possessed well developed lymphoid organs including a clearly differentiated thymus with distinct cortical and medullary zones. However, unlike older fish, the juvenile mullet usually failed to produce antibody in response to a single injection of classical thymus‐dependent antigen (using the soluble proteins human gamma globulin or keyhole limpet haemocyanin). Prior priming of the juvenile fish with antigen was found to potentiate antibody production following challenge with a second dose of the antigen in adjuvant, priming by oral administration being equally as effective as priming by injection. Neither juvenile nor adult mullet produced any significant level of antibody against ovalbumin.The results suggest that, despite their apparently well differentiated lymphoid organs, juvenile mullet still show a certain level of immaturity in their antibody responses to soluble proteins; also that immunization can improve their ability to respond.
A new look at optimal foraging behaviour; rule of thumb in the rainbow trout
Authors: Bres M. 
Published: January 2006

A realistic model of foraging behaviour in stream‐living rainbow trout was developed to address some shortcomings of previous tests of optimal foraging theory. The model predicts prey selection based upon both energy‐maximization and number‐maximization strategies. Trout diet selection on the basis of prey size and prey calorific content was examined under laboratory conditions.Diet composition was strongly influenced by relative abundance of prey types under all feeding regimes, as predicted by the model. Additional important factors include fish stomach capacity and daily digestive capacity. Experimental results strongly suggest that prey selection in rainbow trout is not based on calorific content. Examination of energy (kJ) obtained from observed diets showed no energy penalties associated with ‘suboptimal’ food choices, since all fish (regardless of their choices) consumed far more energy than required for their basic metabolic needs.
Effects of size, culling and social history on growth of cultured elvers, Anguilla anguilla (L.)
Authors: Wickins J. F. 
Published: January 2006

The growth of newly‐caught elvers was measured after they were separated into four size categories and induced to feed. All sizes grew equally well, indicating that size differences at capture reflected migration history rather than the presence of genetically poor or good growers. Socially experienced groups of elvers of equivalent size grew, on average, less well due to the presence of socially suppressed fish and fish that did not respond so well to handling or a new social environment.Replicate groups of rapidly‐growing elvers were culled at either 2‐ or 4‐weekly intervals. The large animals removed were replaced by animals of modal size and the growth of selected residual size groups was compared to unculled control groups. Culling tended to increase the instantaneous growth coefficient of remaining small elvers but the added elvers of modal size may have exerted a disproportionate influence on mean growth rates.The effect of large elvers on the growth of small elvers (and vice versa) was monitored using fish labelled subcutaneously with acrylic paint. Separate populations of elvers of each size group were used as controls. After 82 days in mixed populations, about 36% of the original large fish had been’ overtaken’ by small category fish.The results suggested that, following disturbance, the expression of growth in elvers was not necessarily related to size or previous hierarchical position but may be governed by behavioural or physiological responses to handling and changed social environments.
The influence of ration size and feeding frequency on ammonia excretion by juvenile Atlantic cod, Gadus morhua L.
Authors: Ramnarine I. W. , Pirie J. M. , Johnstone A. D. F. , Smith G. W. 
Published: January 2006

Small groups of juvenile Atlantic cod, Gadus morhua L., were kept at 14°C in through‐flow tanks and were fed known quantities of a compounded diet of natural food. The cod were fed single and multiple meals with ration size in the range 0.5 to 4.1% of total wet fish body weight. Ammonia production in each feeding experiment was monitored continuously.For single‐meal experiments, significant relationships were derived between ration size and (a) total ammonia excreted, (b) total exogenous ammonia excreted above endogenous excretion levels, (c) duration of the elevated phase of ammonia excretion, (d) maximum rate of ammonia excretion, and (e) time delay after feeding to reach maximum rate of ammonia excretion. Relationships between nitrogen loss as ammonia and nitrogen intake were examined and estimates of endogenous excretion rate and maintenance ration made.Repetitive feeding resulted in cyclical variation in ammonia excretion. At the lowest ration size, ammonia excretion rates had nearly returned to the pre‐feeding level within 24 h. At higher feeding levels, the effect of each successive meal tended to be cumulative, resulting in increasingly higher ammonia excretion rates which only stabilized towards the end of the experiments.
The relative importance of the gills to ammonia and urea excretion in five seawater and one freshwater teleost species
Authors: Sayer M. D. J. , Davenport J. 
Published: January 2006

The classic Homer Smith divided box experiment (Smith, 1929) was repeated upon five marine and one freshwater teleost species. Of the nitrogenous output (as ammonia and urea), 50–70% occurred in the head region for marine teleosts, while the freshwater tilapia studied excreted 90% from the head. Together with the data of Smith, these data indicate that nitrogen excretion by the gills is of lesser importance in marine teleosts than in freshwater species.In the dab, Limanda limanda, the head, anus and urinary opening were all in the anterior chamber of the divided box, but 47% of nitrogen excretion still occurred in the posterior chamber, presumably across the skin. In the blenny, Blennius pholis, exposed to air, the head region accounted for 46% of urea elimination, and 26% of ammonia output.
Behavioural and physiological adaptations to a burrowing lifestyle in the snake blenny, Lumpenus lampretaeformis, and the red band‐fish, Cepola rubescens
Authors: Atkinson R. J. A. , Pelster B. , Bridges C. R. , Taylor A. C. , Morris S. 
Published: January 2006

Observations have been made on the mode of burrow construction in the snake blenny, Lumpenus lampretaeformis, under laboratory conditions. It appears that head probing and lateral oscillations of the body are principally responsible for the excavation of the burrow which is completed within 24 h. The burrow structure has been analysed in detail, showing a mean depth of 7.2 cm with a maximum observed length of 73 cm, with most systems between 20 and 35 cm in length. Initially linear burrows with two openings are usually provided with a small side tunnel, giving the system a characteristic Y‐shape.Burrow irrigation was investigated for the first time in L. lampretaeformis. The mean duration of burrow irrigation, by flexions of the tail of the fish, was 21 s with over 13 min h−1 spent in irrigating the burrow. The mean water displacement per irrigation period was 3.1 ml. The PO2 and PCO2 were measured in both surface water and within the burrow system of L. lampretaeformis. Surface water values for PO2 were high (> 150 Torr) and PCO2 low (<0.4 Torr). Hypoxic and hypercapnic conditions were measured in the burrow system itself, with PO2 values ranging between 57 and 129 Torr and PCO2 rising to > 1.3 Torr in some burrows.A comparative study of Cepola rubescens burrows indicated similar surface water PO2 and PCO2 values as in L. lampretaeformis. Burrow water PO2 values ranged between 60 and 94 Torr, with PCO2 values as high as 1.5 Torr being recorded. These results are discussed in relation to the adaptation of both species to a burrowing lifestyle.
Ontogeny of enzymatic activities in fed and fasting turbot, Scophthalmus maximus L.
Authors: Cousin J.C.B. , Baudin‐Laurencin F. , Gabaudan J. 
Published: January 2006

The presence and localization of acid and alkaline phosphatase, non‐specific proteases, aminopeptidase, amylase, non‐specific esterase and lipase was investigated by histoenzymologic methods in fed and fasting turbot from day 1 to day 40 post‐hatching and compared with published data. Alkaline phosphatase and aminopeptidase activities were delected at day 1 in the distal region of the developing digestive tube. At day 3 (opening of the mouth) aminopeptidase and alkaline phosphatase activities were found all along the intestine. Sites of non‐specific esterase and protease activities became apparent in the digestive tract at days 2 and 3 respectively. Amylase was present in the exocrine pancreas at day 3 and in the lumen of the intestine at day 4. Acid phosphatase was active in the cellular structure surrounding the yolk stores and in the lipid droplets at day 1 and in the intestinal epithelium at day 3. Lipase was found at day 15 when the larvae metamorphose into juveniles.All the investigated enzymes were detected in fasting animals, except for lipase. However, the intensities of the enzymatic activities were weaker in the fasting specimens relative to the fed specimens between days 7 and 10.
A study of the histology and morphology of the digestive tract of the sea‐bream, Sparus aurata
Authors: Cataldi E. , Cataudella S. , Monaco G. , Rossi A. , Tancioni L. 
Published: January 2006

The anatomy and the histology of the digestive tract of young and adult sea‐bream is described from studies using light and scanning electron microscopy. The dentition in the juvenile (25–30 mm long) comprises all canine‐like teeth, to which plate teeth and transition elements are added in the adult.The oesophagus shows a multi‐layered mucosa in the upper part, and single‐layered regions in the lower part. The multi‐layered regions are formed by epithelial cells, mucus‐secreting cells and by cells rich with eosinophilic granules.The Y‐shaped stomach, clearly distinguishable, has a single‐layered columnar epithelium under which, in the cardiac and fundic portion, gastric glands, comprised of all similar cells, are present. The pyloric region is characterized by four caeca, to the base of which the ductus pancreaticus and the ductus hepaticus discharge.The pancreas is composed of small masses spread along the upper intestine; in the adult, pancreatic infiltrations can be seen in the liver.The intestine is short (relative length 0.5–0.6). The intestine epithelium consists of columnar cells intercalated with mucus‐secreting cells. A funnel‐like valve marks the passage to the intestine terminal region, characterized by a mucosa of cells with an abundance of vacuoles full of eosinophilic granules.
Development of the activities of oxidative, glycolytic and muscle enzymes during early larval life in three families of freshwater fish
Authors: Hinterleitner S. , Platzer U. , Wieser W. 
Published: January 2006

The development of the activities of oxidative (COX, CS), glycolytic (PFK, PK, LDH) and muscle enzymes (CK, MK, Pase) was studied in representatives of the families Coregonidae, Salmonidae and Cyprinidae, from hatching to an age of approximately 100 days. In addition, the activities of two enzymes of amino acid metabolism (GOT, GPT) were followed in rainbow trout and in roach.Water content of fresh body weight and protein content of dry body weight decrease during the early larval period. Specific activities of the two oxidative enzymes decline, whereas those of glycolytic and muscle enzymes increase in all species.A family‐specific event is the enormous increase in glycolytic and muscle enzymes from very low values in the early larva to very high levels in adult Coregonus sp. In rainbow trout, CS activity begins with a low‐level period lasting throughout the yolk‐sac period, whereas in the other species CS activity is high immediately after hatching.Acclimation to either 15 or 20° C has no effect on the mass‐specific activities of PFK, M K, CK and Pase in roach and chub, but the former three enzymes appear to be strongly dependent on rearing conditions during the early larval period, whereas Pase is not.
Haematological and haematopoietic response to acid stress in an air‐breathing freshwater fish, Channa punctatus Bloch
Authors: Dheer J. M. S. , Dheer T. R. , Mahajan C. L. 
Published: January 2006

Response of Channa punctatus to acidic water was studied by exposing fishes to pH 3.5, 4.5, 5.5 and 6.5 for 6 weeks. Growth and mortality data indicated increasing stress as the acid level in the ambient water increased. While no mortality was recorded at pH 6.5, a distinct loss of weight compared to continuous gain in body weight in control fish indicated stress. As the pH level decreased, the rate of loss in body weight increased accompanied by mortality which rose to as high as 60% within 3 weeks in fishes exposed to water at pH 3.5.Haematological investigations confirmed the general stress indicated by growth and mortality data. Thus. RBC and related values indicated overall polycythemia. However, eosinophils, basophils. and large and small lymphocytes showed a distinct fall in number as compared to the control.Correlated haematopoietic studies revealed that both the initial and penultimate stages in RBC and neutrophil development recorded an increase parallel to that observed in peripheral blood, but intermediate stages, probably because they were unable to keep pace with the fast turnover, showed a relative decrease.Biochemical investigations showed an increase not only in blood glucose level but also in liver glycogen content. However, there was a significant decrease in muscle glycogen reserves.The significance of these changes is discussed.
Factors limiting fish populations in the Loch Fleet system, an acidic drainage system in south‐west Scotland
Authors: Turnpenny A. W. H. , Dempsey C. H. , Davis M. H. , Fleming J. M. 
Published: January 2006

Loch Fleet is an oligotrophic upland lake in Galloway, south‐west Scotland. It once supported a brown trout, Salmo trutta L., sport fishery with low annual catches (< 150 fish year −1) but catches declined markedly after 1950 and no fish were caught after 1975. Diatom records for the lake sediments indicate acute acidification since 1975, pH changing from c. 5–8 to 4–6.In 1984 a project was set up at Loch Fleet to investigate techniques of acidity mitigation, with a view to restoring fisheries in this and similarly affected waters. An underlying assumption of the project was that fish had been lost as a direct result of acidity and associated factors. Studies were therefore undertaken during a 2‐year baseline period (1984–1986) to validate this assumption.Fish surveys using a variety of techniques (gill‐netting, trapping, electrofishing) confirmed that trout were absent from the Loch and its afferent streams, and also from its main outlet stream, the Little Water of Fleet, for a distance of 7 km downstream. Trout were present below this point but are prevented from passing upstream by a 5‐m waterfall. Eels, Anguilla anguilla L., were present throughout the Little Water of Fleet, though not in the Loch itself. Population densities of both species were low, with less than 7 eels and 5 trout per 100 m2.Survival studies using brown trout ova and yolk‐sac fry indicated that conditions in the Loch and its afferent streams were acutely toxic to these stages as a result of the low pH (pH 4.5), low calcium (I mg l−1) and high aluminium concentrations (200 μg 1 −1 total Al, 60 μg 1 −1 inorganic monomeric Al). Trout fingerlings could survive these conditions in short‐term tests (9 days) but, in chronic exposure tests lasting up to 180 days carried out in situ in streams adjoining the loch, no fish survived this period. This toxicity was eliminated in experiments where pH was raised to 5.4 by KOH addition.It is concluded that the loss of the brown trout fishery at Loch Fleet occurred as a direct result of acidity and related factors, probably acting in the first instance on the sensitive intra‐gravel ova and yolk‐sac fry stages, leading to recruitment failure.
Structural characteristics of the epidermal mucosa in yellow and silver European eel, Anguilla anguilla (L.)
Authors: Saglio Ph. , Escaffre A. M. , Blanc J. M. 
Published: January 2006

Histological observations were made on the distribution and concentration of the superficial mucous cells and on the thickness of the epidermis in immature yellow and in male and female silver eels. In all groups there was a decrease in the concentration of mucous cells from the anterior regions to the posterior regions, while the epidermis was thickest in the median parts of the body. Besides these common characteristics, a sexual dimorphism was shown: in silver eels the epidermis is thicker than in immature yellow eels; female silver eels have both the thickest epidermis and the greatest concentration of superficial mucous cells.Results are discussed in the light of knowledge on the influence of environmental and endocrine factors on the structure and function of epidermal mucosa in teleosts.
Aetiology of ‘red spot’ disease (vibriosis) with special reference to the ectoparasitic digenean Prototransversotrema steeri (Angel) and the sea mullet, Mugil cephalus (Linnaeus)
Authors: Rodgers L. J. , Burke J. B. 
Published: January 2006

The ectoparasitic digenean trematode Prototransversotrema steeri was observed to infect a wide range of estuarine fish species of southern Queensland. The intensity and incidence of trematode infections on Mugil cephalus hosts were recorded and appeared to alter with the estuarine movement of the sea mullet host.Highest trematode population densities were present on post‐spawning M. cephalus which had recently traversed brackish estuarine waters. Similarly, the highest prevalence of external ‘red spot’ lesions was also recorded from such fish.The degree of complicity between P. steeri and ‘red spot’ bacterial pathogens was examined and is discussed. ‘Red spot’ or ‘ulcer disease’ is presented as a disease of multiple aetiology. It is suggested that some ectoparasites and a variety of primary and secondary bacterial pathogens may interact with environmental and behavioural factors to determine the prevalence of external lesions within each affected fish species.
Kidney morphology in sturgeons: a microdissectional and ultrastructural study
Authors: Gambaryan S. P. 
Published: January 2006

The anatomy and ultrastructure of nephrons were studied in various euryhaline and freshwater sturgeons. Microdissection failed to reveal marked differences in the nephron structure between freshwater and euryhaline fishes which might be considered as specific adaptations to the salinity of the environment. Some adaptive changes in the nephron structure were revealed by electron microscopic examination. The glomerular basal membrane is thicker in euryhaline sturgeons than in the freshwater sterlet. The processes of mesangial cells penetrating the basal membrane are much more numerous in fishes caught in the sea than in those from fresh water. Euryhaline sturgeons exhibit a great variability in the ultrastructure of epithelial cells of proximal and distal tubules. The number of mitochondria‐rich cells possessing well‐developed basolateral foldings is significantly higher in fishes caught in the sea. In the freshwater sterlet the ultrastructure of the epithelium of proximal and distal tubules resembles that in freshwater teleosts.Comparison was made of the kidney morphology and ultrastructure in sturgeons, elasmo branchs and bony fishes. It is speculated that in sturgeons the adaptation to varying salinity is achieved by changes in the ultrastructure of glomeruli and differentiation of the cells of the tubular epithelium.
Observations on the nesting habits of Oreochromis mossambicus (Peters) (Pisces: Cichlidae) in Sri Lankan reservoirs
Authors: de Silva S. S. , Sirisena H. K. G. 
Published: January 2006

The nest‐building characteristics of Oreochromis mossambicus (Peters) were studied in five manmade lakes (reservoirs) Sri Lanka. The nests were always found in clusters (arenas) and were generally located in or near coves and/or bays in shallow water. The density of nests in an arena varied between arenas in a reservoir and between reservoirs. The overall mean density of nests ranged between 0.47 and 6.31 m 2 in the five reservoirs. The nests ranged from 11 to 110 cm in diameter, two size groups of nests being recognizable: small, with diameter 10–50 cm, and large with diameter >50 cm. At any nesting site only one size group of nests was found.Nest diameter (ND) was curvilinearly related to mean nest density (D) and linearly to mean distance between nests (Dis), the respective statistical relationships being

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The diameter of nests was also related to nest depth (Dep) as

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There was no apparent relationship between nesting characteristics and morphometric characters of the reservoirs.
Seasonality, depth and habitat distribution of breeding males of Oreochromis spp., ‘chambo’, in Lake Malawi National Park
Authors: McKaye K. R. , Stauffer J. R. 
Published: January 2006

The temporal pattern of breeding by chambo, Oreochromis spp., and the vertical and horizontal distribution of territorial males at the Golden Sands‐Chembe beach were examined in the Cape Maclear region of Lake Malawi National Park. The breeding season began in September and ended in April, and the number of breeding males between 3 and 15 m was approximately 25 ha. Along the beach studied, the highest concentrations of nests were found at the ends of the beach near rocks, and the lowest number of breeding males occurred in front of Chembe villageResults from experimental gill netting demonstrated that the catches of chambo within the 100‐m Lake Malawi National Park ‘no fishing zone’ were identical to those outside the 100‐m zone, suggesting that fishermen would suffer little or no loss in catch by being encouraged to fish more than 100 m from the shore. Such a reduction in fishing and disturbance of the shallow water breeding grounds would probably enhance the chambo fishery. Preliminary data are provided on the chambo nest forms found in the Cape Maclear region, and further research is suggested to resolve the question of how many species comprise the genus Oreochromis in Lake Malawi.
Movement rhythms in juvenile Atlantic salmon, Salmo salar L.
Authors: Thorpe J. E. , Morgan R. I. G. , Pretswell D. , Higgins P. J. 
Published: January 2006

Nocturnal downstrean migration of juvenile Atlantic salmon is usually interpreted as increased locomotor activity. The frequency of downstream passages of 0–1 + salmon in an endless stream channel was greater by night than by day in both smoking and non‐smolting fish in autumn and spring. Movement increased at dusk, and decreased after dawn. Mature male 1 + fish moved slightly less than immatures in October, but significantly more in November. Total movement frequency was lower at full moon than at other moon phases, and movement was reduced when the moon was up. Under turbid conditions by day, the threshold water velocity inducing nett downstream movement was 8.2 cm s−1, and the relative velocity of fish swimming downstream was never more than one third that of fish holding station at the normal maximal flow of 25–30 cm s−1.At the end of their first growing season in October, fish which had been offered food continuously through 24 h did not differ in size from those fed by day only, but the latter were significantly larger than those offered food only at night.We conclude that: (1) the fish fed actively by day, and not by night; (2) station‐holding represented activity, and downstream nocturnal movement represented relative inactivity (displacement) which occurred on loss of visual orientation, hence migration resulted from reduced activity; (3) lack of displacement in early autumn has adaptive value for maturing fish, but not for non‐spawners.