Vertebral abnormalities in common bream Abramis brama (L.)

Vertebral abnormalities in bream Abrama bramis (L.) and lesions of the caudal peduncle are described.     

Experimental research on the feeding of bream (Abramis brama L.) and white bream (Blicca bjoerkna L.)

Summary The feeding efficiency (the amount of food organisms (chironomids) eaten per unit time and weight raised to the power 0.8) of bream and white bream was determined in relation to the grain size of the substrate, in which the food was presented. Sand was used as substrate with a grain size up to 1500 , divided in eight fractions. The bream used had lengths of 14 and 33 cm and the white bream had a length of 21 cm.The experiments showed quite clearly that the grain size of the substrate influenced the feeding efficiency of all these fishes. An increasing grain size resulted in an decreasing feeding efficiency, because only up to a definite grain size the substrate can be filtered through the gill rakers. If the grain size is larger, the substrate cannot be sieved and is spit out. The size at which this switch occurred was different for all the fishes. For the small bream it was 350 , for the large bream 500 , and for the white bream 600 .Comparing the feeding efficiencies for a grain size which can be sieved by all these fishes, no significant difference was found between large bream and white bream. The small bream, however, was less efficient. Probably this difference is caused by the different sucking capacities of small and large fish. The small bream cannot in one time suck in the chironomids presented at 1 cm depth, while large bream and white bream can. So both grain size and depth at which the food was presented differentially determined the feeding efficiency of these fishes.     

Effect of GABAergic compounds on the anion-sensitive Mg2+-ATPase from bream (Abramis brama L.) brain

Preincubation of plasma membranes from bream brain with 10-8-10-4 M gamma-aminobutyric acid (GABA) or muscimol increased the anion-sensitive Mg2+-ATPase activity. The activating effect of neurotransmitters on the Mg2+-ATPase is enhanced with increasing preincubation time of the membranes with the ligands, decreases with increasing Mg2+-ATP concentration in the incubation medium, and is inhibited in the presence of the GABAa-receptor antagonist, bicuculline (90 microgr;M). The anions Cl-, Br-, and I- stimulate the basal Mg2+-ATPase activity, and an effect of 10-4 M GABA in the presence of anions was not found. It is supposed that GABAergic chemicals modify the anion-sensitive Mg2+-ATPase in a receptor-dependent way.     

Bottom-up effects of bream (Abramis brama L.) in Lake Balaton

Enclosures (17 m³) were used in the mesotrophic area of Lake Balaton to determine the impact of benthivorous bream (Abramis brama L.) on the lower trophic levels during summers of 1984–86. In enclosures with a fish biomass similar to the biomass in the eutrophic area of the lake, the number of phytoplankton species was highest. In enclosures with a low fish biomass the phytoplankton was dominated by the greens. A high biomass of bream in the mesotrophic basin caused bacterial production corresponding to that of the eutrophic part of the lake. Crustaceans were dominated by copepods and were unable to control phytoplankton peaks. Bottom-up effects of bream were more obvious than top-down effects and seem to be more important in the possible control of water quality.     

A readily recognizable tag for marking bream Abramis brama (L.)

The paper describes the use of chicken wing tags as a rapid method of marking bream, Abramis bvurnu . Experiments on captive fish suggest that mortality due to the tags is minimal, although the results of co-variance analysis show that the tags effect the condition of the fish. An analysis of the recapture data is given.     

Metal-binding proteins in bream (Abramis brama L.) caught in the River Elbe

Metal-binding proteins were investigated in livers of bream caught in the River Elbe from Steti (Czech Republic) to Hamburg (Federal Republic of Germany). A major zinc and copper binding protein fraction with a low molecular weight of 10 000 to 12 000 Da and with properties similar to mammalian hepatic metallothionein was isolated from bream livers using gel filtration chromatography. Two protein isoforms could be separated by reversed phase-high performance liquid chromatography (RP-HPLC), however, mercury was associated with only one isoform. The possibility of different detoxification potentials of the isoforms is discussed. Maximal concentrations of metal-binding protein were detected in samples from Dresden. If metal-binding proteins are to be included in a biological monitoring study, further investigations are required.     

Metal-binding proteins in bream (Abramis brama L.) caught in the River Elbe

Metal-binding proteins were investigated in livers of bream caught in the River Elbe from Steti (Czech Republic) to Hamburg (Federal Republic of Germany). A major zinc and copper binding protein fraction with a low molecular weight of 10 000 to 12 000 Da and with properties similar to mammalian hepatic metallothionein was isolated from bream livers using gel filtration chromatography. Two protein isoforms could be separated by reversed phase-high performance liquid chromatography (RP-HPLC), however, mercury was associated with only one isoform. The possibility of different detoxification potentials of the isoforms is discussed. Maximal concentrations of metal-binding protein were detected in samples from Dresden. If metal-binding proteins are to be included in a biological monitoring study, further investigations are required.     

Success of embryonic development of reciprocal hybrids of bream Abramis brama (L.) and white bream Blicca bjoerkna (L.)

Success of embryonic development of reciprocal hybrids of bream Abramis brama and white bream Blicca bjoerkna was tested under laboratory conditions. Fertilization and embryonic development success of hybrids until hatching was high and comparable to that of pure species.     

On the biology of bream, Abramis brama (L.) in Lake Peipsi in 1994

The population of bream in L. Peipsi was studied with respect to age, growth rate, condition factor (according to Fulton) and length-weight relationship in 1994. That autumn the bream population in L. Peipsi consisted of fishes aged from 0+ to 15+. During the first year bream reached an average body length of 7.9 cm (the commercial legal size (30 cm) was usually attained by the end of the 5th–6th year. The condition of bream in this lake was above the average of Estonian lakes. The relatively good growth rate and condition of bream in the lake indicates that the waterbody is appropriate for this fish.     

Lake water level increase during spring affects the breeding success of bream Abramis brama (L.)

In Lake Constance, Eurasian bream Abramis brama (L.) spawn in very shallow littoral areas by the beginning of May. They attach their adhesive eggs to pebble and cobble substratum at <40 cm depth. Increasing water levels before spawning inundate bare substratum to which bream eggs may attach better than to deeper substratum covered by epilithon. Consequently, the water level increase prior to spawning should determine the amount of pristine spawning substratum available to bream and thus influence their breeding success. In order to test this hypothesis, the influence of hydrology and climate on the abundance of age-0 bream was combined with the results from field investigations on the egg survival and abundance of age-0 bream. A strong positive correlation between the mean water level increase during the spawning season of bream (April–May) and the abundance of juvenile bream was found. In contrast, the absolute water level during spawning and during the nursery stage in summer, the cumulative temperature during the egg, larval and juvenile stages and two North Atlantic Oscillation (NAO) indices did not affect the abundance of juvenile bream. The field investigations confirmed that bream eggs attach better to and have higher survival rates on bare substratum than on substratum with epilithon cover. Accordingly, eggs within a spawning habitat of bream were most abundant between 10 and 20 cm depth, where the epilithon cover was lower than at depths exceeding 30 cm. The results of this study confirm an adverse influence of epilithon cover on the attachment and subsequent survival of bream eggs and emphasize the importance of spring inundations for the successful breeding of the bream. Handling editor: J. A. Cambray     

Influence of development pace on pharyngeal teeth formula in Abramis brama (L.) bream: experimental data

An experiment on acceleration and retardation of ontogenesis with thyroid manipulation has revealed direct changes in definitive dentition of pharyngeal bones in Abramis brama bream. As development pace accelerates, the number of teeth reduces to the formula 5-4. When development pace slows down, this number increases to the formula 6-5. Moreover, an additional minor row of teeth (1.6-5.1, 2.6-5.2) is formed. The observed changes transcend typical changes happening in nature. It is assumed that heterochronies provoke changes in the number of teeth.     

Feeding behavior and brain acetylcholinesterase activity in bream (Abramis brama L.) as affected by DDVP,an organophosphorus insecticide

1. Bream (Abramis brama) were exposed to sublethal concentration of organophosphorus insecticide DDVP and the amount of food consumed and brain acetylcholinesterase (AChE) examined in exposed fish.2. Exposure to DDVP resulted in decreased amount of food consumed and inhibited brain AChE activity.3. Intraperitoneal injection of the fish with cholinergic drugs, atropine and TMB-4 recovered the feecling efficiency in exposed fish. TMB-4 recovered brain AChE activity as well.4. The results revealed that cholinergic system in fish brain constitutes biochemical mechanism controlling feecling behavior in fish.     

Effect of chloride and bicarbonate ions on Mg2+ -ATPase of plasma membranes of bream (Abramis brama L.) brain sensitive to GABAA-ergic compounds

Effect of Cl and HCO3- ions on the Mg2+ -ATPase activity of the plasma membrane of bream brain was investigated. Cl- (5 or 10 mM) and HCO3- (1-5 mM) individually have low effect on the "basal" Mg2+ -ATPase. Simultaneous presence of Cl- and HCO3- in the incubation medium significantly increased the enzyme activity. Maximum effect of anions on the enzyme is observed in the presence of Cl- (approximately 7 mM) and HCO3- (approximately 3 mM). Br- can replace Cl- under joint effect with HCO3-, while I- has half maximum activity compared with Cl-. Bicuculline (7 microM) inhibits completely the joint effect of Cl- and HCO3- on the enzyme, while it has no effect on the "basal" Mg2+ -ATPase activity. SH-reagents (5, 5-dithiobis-2-nitrobenzoic acid, N-ethylmaleimide), oligomycine and orthovanadate inhibited the Cl-, HCO3- -activated Mg2+ -ATPase. The obtained results demonstrated that Mg2+ -ATPase of the bream brain sensitive to GABAergic ligands at a fixed concentrations of Cl- and HCO3- ions in the incubation medium is Cl-, HCO3- -activated by Mg2+ -ATPase, whose activity meets a number of requirements to the system which may be involved by GABAA receptors in the Cl-/HCO3- -exchange processes.     

Prevalence of skin neoplastic lesions in bream (Abramis brama L.) from the Curonian Lagoon of the Baltic Sea

Skin neoplastic lesions have been studied in bream inhabiting the Curonian Lagoon of the Baltic Sea in 1999–2010. A total of 12163 fish specimens have been examined. Two types of lesions have been revealed: epidermal hyperplasia and skin papilloma, considered to be the successive stages of the epizootic cutaneous papillomatosis in fish. This disease has been registered in 18.5% of fish older than 5 years. The share of diseased specimens increases with age and reaches 62.5% in 15-year-old fish. The prevalence of lesions in males is significantly higher (12%) than in females (5.3%). The number of diseased fish in winter (30.2%) is higher than in summer (15.6%). The maximum share of fish with neoplasms has been recorded in 2006 (40%). Since 2007, there has been a trend towards a decrease in the prevalence of skin neoplastic lesions, and the average occurrence of diseased fish has reached 7.3%. The high prevalence of skin neoplasms (SNs) in bream is evidence of the unfavorable ecological situation in the Curonian Lagoon.     

The food of bream (Abramis brama L.) in two basins of Lake Balaton of different trophic status

Contrary to earlier observations the food composition of bream (Abramis brama L.) in Lake Balaton has changed in parallel with eutrophication. These changes were probably caused by increased population density and connected with density dependent growth as well as sharpened inter- and intraspecific competition in the cyprinid community. According to the frequency of occurrence, zooplankton followed by benthic invertebrates comprised the majority of the bream's food. By weight, however, benthic food dominated in both basins. Size-related dietary changes were pronounced, but statistically not always significant, suggesting the overall importance of the most abundant and available prey types. Bream did not strongly select any of the zooplankton groups, however, seasonal changes in food composition alternated in parallel with the trophic gradient along the longitudinal axis of the lake.     

Electrophoretic identification of roach (Rutilus rutilus L.), rudd (Scardinim erythrophthalmus L.), bream (Abramis brama L.) and their natural hybrids

Roach, rudd, bream and their natural hybrids of 2 cm standard length or larger can be definitively identified by their enzyme electrophoretic patterns. Zymograms of lactate dehydrogenase and esterases as produced by vertical starch gel electrophoretic analysis of whole fry or adult eye extracts are the most useful in this respect. The lactate dehydrogenase isozymes, containing B sub-units, migrate more anodally in rudd and bream than in roach. Due to the tetrameric structure of lactate dehydrogenase, in hybrid rudd x roach and roach x bream, eleven isozymes can be observed as compared with six in the parental patterns. Esterases show unique patterns for all species and hybrids. With the exception of one fraction in rudd x bream, the esterase patterns of hybrids show summations of the parental phenotypes.     

A novel, endogenous inhibitor of 7-ethoxyresorufin-O-deethylase activity isolated from liver cytosolic fractions of bream (Abramis brama L.)

The cytosolic supernatant of bream (Abramis brama L.) liver homogenates inhibits the 7-ethoxyresorufin-O-deethylase (EROD) activity of pike (Esox lucius) microsomal fractions. The inhibitor shows no activity against 7-ethoxycoumarin-O-deethylase and benzo(a)pyrene hydroxylase indicating a high isoenzyme specificity. The inhibiting component is a heat-sensitive substance (56 degrees C for 5') which is not self regenerating after subsequent cooling. It can be isolated from the cytosolic fraction using two combined steps of ion exchange chromatography. The purification factor is 500-fold with a recovery rate of 70%. SDS-PAGE of the purified fractions indicate that electrophoretic purity was not achieved. However, a prominent band at about 97 kDa was present in all fractions in a close intensity activity relationship. The molecular weight of the native form of the purified protein was determined to be 175 +/- 35 kDa using gel filtration on a Sephacryl S 300 HR column. So far the inhibitor can be characterized as a protein. It shows strong tendencies to aggregate due to lipophilic interactions. These interactions can be repressed by the addition of 1% sodium cholate. The inhibitor has an optimum activity at 25 degrees C and pH 8.0. The inhibitor does not correspond to any of the known cytosolic, endogenous inhibitors of EROD activities in fish, including proteases, cytosolic phosphatases, kinases and resorufin reductase (e.g. DT-diaphorase), although a non-dicoumarol (10 microM)-inhibited menadione oxidoreductase activity of up to 46.7 +/- 0.4 nmol/min per mg inhibitory protein was measured. Kinetic studies using Michaelis-Menten kinetics with purified inhibitor fractions prove a non-competitive mode of inhibition. As this kind of inhibitor is not described yet it is named CERODIP (cytosolic, EROD-inhibiting protein).     

Fertility of roach × bream hybrids, Rutilus rutilus (L.) ×Abramis brama (L.), and their identification

Adult roach, bream and their presumed F₁ hybrid from an Anglian Water reservoir were identified on the basis of morphological and meristic characteristics. The hybrid was clearly intermediate. Four hybrid breeding crosses were induced to spawn by hypophysis. A bream × roach cross (female named first) failed to produce fertile eggs, whereas F₁ hybrid × roach, roach × F₁ hybrid and F₁ hybrid × F₁ hybrid all produced fry. Fertility (defined as survival of eggs to hatching) was high for the F₁ hybrid × roach back-cross (56%) but low for the others (<2%), in comparison to the pure species controls (roach 69%, bream 76%). Progeny from these crosses were reared until anal fin rays could be counted. These counts indicated intermediacy between the parents and back-crossed individuals, and similarity between F₁ hybrids and their F₂ progeny.