Male Bream Research Articles

Interannual variability of the functional state of bream (Abramis brama, L.) of the delta Volga in the pre-spawning period

Bream is an important fishing object of the Volga-Caspian region. Its catches here in the middle of the last century reached 60 thousand tons, while currently they do not exceed 14 thousand tons. The study of the functional state of bream in the pre-spawning period makes it possible to determine the success of spawning, predict the survival of offspring at the early stages of ontogenesis. During the spawning periods (2007–2017 and 2021), the functional state of female and male bream caught in the waters of the delta Volga was studied. To assess the physiological state, the following biochemical parameters of blood were analyzed: the amount of hemoglobin, total serum protein, β-lipoproteins, cholesterol, total lipids, triglycerides, inorganic phosphorus, glucose, activity of alkaline phosphatase and aspartate aminotransferase, generally accepted methods of hematological and biochemical studies of blood and blood serum were used. The work used generally accepted methods of hematological and biochemical studies of blood and blood serum. As a result, there were statistically significant differences in the values of such indicators as the level of hemoglobin in the blood, cholesterol and β-lipoproteins cholesterol, glucose between females and males were noted. Significant interannual differences in the values of the studied indicators were revealed. The flow regime and the volume of spring flood had a decisive influence on the functional state of bream in the prespawning period. Deviations from the values of these indicators from the limits of reference values characteristic of fish and bream, in particular, taken from literary sources, were usually observed in low-water years (hemoglobin, β-lipoproteins, total lipids). The average level of correlation (r = 0.50) between the value of total whey protein and cholesterol was established in bream, which indicates a close relationship between protein and lipid metabolism. Thus, the physiological state of the Lower Volga bream in the pre-spawning period of high-water years can be characterized as relatively favorable.

Impact of habitation conditions on metabolism in the muscles, liver, and gonads of different sex and age groups of bream

Impact of the factors of the aquatic environment is an inevitable aspect of the life of fish as poikilothermic animals and provokes responses in their organisms. The study focused on determining peculiarities in the composition of the metabolic products in the tissues of different age and sex groups of common bream Abramis brama (L.) depending on the living conditions in the water reservoirs of the Upper Volga. The fish were captured in the fattening period in summer and autumn, measured, weighed, identifying sex, maturity stage of the gonads and age. In the muscles, liver and gonads of bream, we analyzed the contents of water, dry matter, lipids, protein, ash and carbohydrates using the standard techniques. The contents of biochemical components in the organism of bream were to a higher degree determined by the peculiarities of the living conditions rather than sex and age of the individuals. In the muscles and liver of bream living in the conditions of increased water temperature and low concentration of oxygen, the concentrations of protein and ash were lower. In the same tissues of bream from the water bodies with high concentrations of pollutants in the water and benthic deposits, we found increased fat content. The muscles of male bream contained less protein and more carbohydrates than females and juvenile individuals, and the muscles of juveniles had less fat. The environmental factors had greater influence on the content of the metabolic products in the liver of bream than sex, and only females had higher ash content than males. The testes had more fat and less protein than the ovaries. During the transition of the gonads from maturity stage II to III, the contents of dry matter and lipids in them decreased. We determined that the environmental factors have stronger impact on biochemical parameters in the tissues of bream than age, because we found no general age patterns in the dynamics of biochemical components, except the liver, in which the highest content of organic compounds was found in individuals aged 6 to 10 years. Water heated by the Hydro Power Plant positively influenced the young bream, as indicated by higher content of metabolic products in individuals aged 5+ than older groups and bream from the surveyed water bodies. Monitoring of the physiological condition of bream focusing on the contents of metabolic products in the tissues may provide necessary data for successful regulation of bream populations in the water reservoirs of the Upper Volga.

Dynamics of indices of metabolism in muscle tissue, liver and gonads of Abramis brama in different periods of the annual cycle

The aim of this research was to study the dynamics of metabolism in the body of bream Abramis brama (L.) at different periods of the annual cycle: pre-spawning, spawning, post-spawning and feeding. The object of the study was 55 male and 53 female bream aged 9–13 years, to reduce the effect of age on the studied parameters. Individuals were measured, weighed, gender was determined, gonad maturity stage, age; the condition factor and organ indices were calculated. The content of moisture, dry matter, lipids, proteins, ash and nitrogen-free extracts (NFE) in the muscles, liver and gonads of male and female bream have been analyzed. The lowest coefficients of condition factor were found in bream during the autumn feeding season, the highest in males during spawning, in females before and after spawning. In the muscle tissue of male and female bream the content of metabolic products in the feeding period and before spawning differed slightly. In the spawning period, the muscles of males exceeded the muscle tissue of females in lipid content by more than two times. In the annual cycle of the bream, the ovaries contain more protein than the testes. The bream of different sex revealed differences in the intensity of metabolic processes during the maturation of gonads: in males, energy costs are more pronounced after wintering before spawning, while in females, during spawning. The main energy reserve in the form of lipids in the annual cycle changes more significantly in the body of male bream than in females. Ovarian maturation requires more metabolite reserves than maturation of the testes, however, males have increased expenditure associated with reproductive behaviour during spawning. Therefore, the total energy contribution to reproduction may be the same for female and for male bream. Bream’s liver and muscle tissue can serve as a source of energy during food shortages and during spawning. In the annual cycle, the condition factor of bream increases due to an increase in the moisture content in the muscles.

Sexual and age characteristics of the parasitofauna of Abramis brama (Cypriniformes, Cyprinidae) of the Lower Irtysh (Russia)

In the present study, an evaluation was made of the dependence between infections by various types of parasites and the sex and age of the host. The parasitic community of Abramis brama includes 24 species of parasites. We assessed the degree of infestation by parasites in groups of male, female and juvenile specimens. It was established that only male bream were infested with Zschokkella nova (Klokacewa, 1914), Hysteromorpha triloba (Rudolphi, 1819), Allocreadium isoporum (Looss, 1894), Ichthyocotylurus platycephalus (Сrерlin, 1852). The ciliates of Trichodina nigra (Lom, 1960) were noted on the gills and fins of all the examined fish, the extensiveness of infection in the group of juveniles exceeded that of the groups of females and males. Specimens of Myxobolus rotundus (Nemeczek, 1911) were found on the gills and in the kidneys, and M. parviformis only on the gills of the fish. The level of infection in males was three times the EI in females and juvenile fish. The infestation on the fins by the metacercaria of Rhipidocotyle campanula (Dujardin, 1845) in male bream was more than 6 times higher than infection in females and juveniles. An increase in the extensiveness of infection in males by the nematode Philometra ovata (Zeder, 1803) was also noted in comparison with groups of females and juvenile fish. Species-specific monogeneans: Dactylogyrus falcatus (Wedl, 1857), D. wunderi (Bychowsky, 1931), D. zandti (Bychowsky, 1933), Gyrodactylus elegans (Nordmann, 1832); the trematodes Sphaerostomа bramae (Müller, 1776) and Diplostomum chromatophorum (Brown, 1931) infested all individuals of bream in approximately the same proportion, whereas an increase in the EI of the Caryophyllaeus laticeps (Pallas, 1781) cestode in males was observed. Infection with metacercariae Metorchis sp. in males exceeded that in females and juvenile fish. At the same time, only females and juvenile bream were infected by Chilodonella sp., metacercariae Opisthorchis felineus (Rivolta, 1884) and glochidia Unionidae gen. sp. During the studies in females, the following species of parasite were observed singly : Proteocephalus sp., Azygia lucii (Miiller, 1776), Ergasilus sieboldi (Nordmann, 1832). Parasitization by Raphidascaris acus (Bloch, 1779) was recorded only in males and juveniles, whereas in females this parasite was not observed. The dominant parasite in males was G. elegans, in females – the representatives of the genus Dactylogyrus, in the juvenile individuals the trematode S. bramae dominated. Analysis of the parasite fauna in various age groups allowed us to establish that at the age of 5+–6+ bream were infected by 20 species of parasites, in age group 3+–4+ there were 15 species, at the age of 7+–8+ the fish were infected only with 11 parasitic species. The fish in all three groups were infected by T. nigra, Dactylogyrus spp., G. elegans, D. chromatophorum, S. bramae, R. acus almost at the same level and had no sharp differences in extensiveness and abundance of infection. Unionidae gen. sp. were observed only in group 3+–4+. Parasitization by Proteocephalus sp., metacercariae H. triloba and I. platycephalus, A. isoporum, and A. lucii was found in bream of age group 5+–6+, the species did not occur in bream at other ages. Nematode P. ovata and crustacean E. sieboldi infested the fish in age groups 3+–4+ and 5+–6+ with a slight increase in the extensiveness of infection at low abundance rates. The same age groups were observed to have decrease in the extensiveness of infection with Chilodonella sp. and metacercariae O. felineus. Myxozoan Z. nova parasitized in age group 5+–6+ and had an increase in extensiveness in age group 7+–8+. In all groups, infection was noted by representatives of the genus Myxobolus, R. campanula and Metorchis sp. with EI increasing with age. The obligate parasite of bream – C. laticeps infested fish the most in age group 3+–4+ in comparison with age groups 5+–6+ and 7+–8+. In the younger age group, the dactylogyruses were dominant parasites, in the age group 5+–6+ Gyrodactylus dominated, in the older age group – Metorchis sp.

Surveying black bream, Spondyliosoma cantharus (L.), nesting sites using sidescan sonar

Black bream, Spondyliosoma cantharus (L.), are summer visitors to the south and west coasts of the UK, overwintering in deeper waters and migrating inshore to breed from April to June. Bream are demersal spawners, with the eggs laid in a nest excavated by the male as it creates a depression in a sandy gravel substrate. To build their nests, male bream expose bedrock and gravel by using their tails to remove the surface layer. The present study, using sidescan sonar and SCUBA diving, extends the known occurrence of extensive nesting grounds off the West Sussex coast to the Isle of Wight and Dorset. The nests are typically circular craters 1-2m wide, and 5-30cm in depth, which can clearly be seen using sidescan sonar as groups of circular depressions. Several thousands of eggs (1-2mm) are attached to bare rock in the centre of these structures. All the eggs hatch by July. The species is valuable and particularly vulnerable to exploitation by both sport and commercial fishermen during its nesting season. With no minimum landing size and no prescription for Total Allowable Catch or the International Council for the Exploration of the Sea (ICES) stock assessment, they are suitable for protection under spatial planning measures, such as through the use of marine protected areas (MPAs).

Biomonitoring of estrogenic exposure and identification of responsible compounds in bream from Dutch surface waters

The exposure to and effects of estrogenic compounds in male breams from Dutch freshwater locations were investigated. Ovotestis was observed infrequently (maximum frequency 16%). However, plasma vitellogenin (VTG) concentration was elevated highly at some locations. Estrogenic activities in male bream plasma, liver, and in gastrointestinal content were measured in the estrogen-responsive chemical-activated luciferase gene expression (ER-CALUX) assay. Plasma concentrations of vitellogenin correlated very well with the estrogenic activities in gastrointestinal content. The ER-CALUX activity in gastrointestinal content thus could provide a biomarker for recent exposure to estrogenic compounds, and the gastrointestinal content was chosen as investigative matrix for the toxicity identification and evaluation ([TIE]; bioassay-directed fractionation) of estrogenic compounds in bream. The approach consisted of a reversed-phase high-performance liquid chromatography fractionation of gastrointestinal content extract, directed by ER-CALUX and followed by gas chromatography analysis. The estrogenic hormones 17beta-estradiol and its metabolite estrone were identified as major contributors to the activity at all locations (except the reference location), independent of the presence or absence of a known source of estrogenic activity, such as a sewage treatment plant. Chemical screening showed the presence of other pollutants, such as a lower chlorinated dioxin and the disinfectants clorophene and triclosan. However, these compounds did not have high estrogenic potencies and their concentrations were not high enough to contribute significantly to the observed estrogenic activity.

An integrated assessment of estrogenic contamination and biological effects in the aquatic environment of The Netherlands

An extensive study was carried out in the Netherlands on the occurrence of a number of estrogenic compounds in surface water, sediment, biota, wastewater, rainwater and on the associated effects in fish. Compounds investigated included natural and synthetic hormones, phthalates, alkylphenol(ethoxylate)s and bisphenol-A. The results showed that almost all selected (xeno-)estrogens were present at low concentrations in the aquatic environment. Locally, they were found at higher levels. Hormones and nonylphenol(ethoxylate)s were present in concentrations that are reportedly high enough to cause estrogenic effects in fish. Field surveys did not disclose significant estrogenic effects in male flounder ( Platichthys flesus) in the open sea and in Dutch estuaries. Minor to moderate estrogenic effects were observed in bream ( Abramis brama) in major inland surface waters such as lowland rivers and a harbor area. The prevalence of feminizing effects in male fish is largest in small regional surface waters that are strongly influenced by sources of potential hormone-disrupting compounds. High concentrations of plasma vitellogenin and an increased prevalence of ovotestes occurred in wild male bream in a small river receiving a considerable load of effluent from a large sewage treatment plant. After employing in vitro and in vivo bioassays, both in situ and in the laboratory, we conclude that in this case hormones (especially 17α-ethynylestradiol) and possibly also nonylphenol(ethoxylate)s are primarily responsible for these effects.

Identification of Estrogenic Compounds in Fish Bile Using Bioassay-Directed Fractionation

Conjugates of estrogenic chemicals, endogenous as well as xenobiotic, are mainly excreted via bile into the intestine. Therefore, measurement of estrogenic activity in bile yields useful information about an organism's internal exposure to (xeno-)estrogens. Although previous studies in The Netherlands have reported estrogenic activity in male fish bile, the contribution of natural hormones and xenobiotic substances to this activity is unknown. To identify compounds responsible for estrogenic activity in fish bile, we developed a bioassay-directed fractionation method for estrogenic chemicals. In this approach, the in vitro reporter gene assay ER-CALUX (Estrogen Responsive Chemical Activated Luciferase Gene Expression) was used to assess estrogenic activity in deconjugated bile samples and to direct RP-HPLC fractionation and chemical analysis (by GC-MS) of estrogenic compounds. The method was applied to bile from male breams (Abramis brama) collected at three locations in The Netherlands. At one of these locations, the River Dommel, extremely high levels of plasma vitellogenin and a high incidence of intersex gonads in these male breams have previously been observed, indicating the exposure to estrogens. In this study, the natural hormones 17beta-estradiol, estrone, and estriol accounted for the majority of estrogenic activity in male bream bile. At the River Dommel, the synthetic contraceptive pill component ethynylestradiol was found in effective concentrations as well. The detected natural and synthetic hormones may be responsible forthe estrogenic effects observed in wild bream from this location. Furthermore, a large number of xenobiotic chemicals was detected at relatively high levels in bile, including triclosan, chloroxylenol, and clorophene. Although chloroxylenol was shown for the first time to be weakly estrogenic, these compounds did not contribute significantly to the estrogenic activity observed.

Estrogenic effects in fish in The Netherlands: some preliminary results

Recently, a large-scale field study in The Netherlands has focused on the effects of estrogenic contaminants on feral fish populations. The freshwater bream ( Abramis brama) and the estuarine flounder ( Platichthys flesus) were sampled at a large number of locations in the spring and autumn of 1999. Concentrations of the yolk protein vitellogenin (VTG) in blood plasma of male flounders were small at most sites. At two sites, however, moderately elevated concentrations were found in autumn. Both sites were situated in the same industrial harbour zone also receiving effluent from sewage treatment works. At many sites VTG levels in male bream were significantly greater than at the control site. The greatest concentrations were observed in individuals collected from a small stream, close to the discharge of a relatively large municipal waste water treatment plant. This was also the only site where considerable intersex occurred; 37% of male bream exhibited ovotestes. Ovotestis was not observed in any of the male flounder captured. The results from The Netherlands are briefly discussed and compared with the well-known case studies in the UK.

Plasma biomarkers in fish provide evidence for endocrine modulation in the Elbe River, Germany.

Blood plasma samples were collected from wild bream (Abramis brama L.) in the Elbe River, Germany, and analyzed for the yolk protein precursor vitellogenin (VTG), a biomarker for estrogen exposure, and the sex steroids 11-ketotestosterone (11KT), testosterone (T), and 17beta-estradiol (E2) to investigate for evidence of endocrine modulation. In addition, the gonadal status and the prominence of spawning tubercles were investigated. Nine riverine sites were investigated on the Elbe that were influenced by different sources of endocrine-active substances. Bream were collected from a lake that received no domestic or industrial discharges as a control. Plasma VTG concentrations were significantly higher in male bream from the Czech border to the middle Elbe, with the highest concentrations in fish sampled at the locations near Magdeburg and downstream of Dresden (between 20 and 100 times higher than in the controls), regions that are characterized by high levels of effluent discharges into the river. Following the Elbe from this site to the sea, the concentrations of plasma VTG in males were lower than at Meissen but were still elevated above the controls. 11KT and E2 titers showed suppressions in their normal concentrations at some locations (those receiving the greatest industrial discharges). There were reciprocal relationships between inhibitory effects on gonadal growth, maturation, and plasma sex steroids and exposure to pollutants, such as organotins, pesticides, or metals. However, there was no single chemical that alone could explain the observed inhibitory effects on sexual development. The results indicate that the endocrine system in wild bream is disrupted in stretches of the Elbe River.

Biological measurement of estrogenic activity in urine and bile conjugates with the in vitro ER‐CALUX reporter gene assay

Although estrogens are excreted as biologically inactive conjugates, they can be reconverted to an active form, possibly by bacteria. A simple method was developed to deconjugate estrogen metabolites present in human urine and fish bile back to active estrogens by enzymatic hydrolysis with beta-glucuronidase or live Escherichia coli cells. Deconjugated extracts were tested for estrogenic activity in the in vitro stable estrogen receptor-mediated chemical-activated luciferase gene expression (ER-CALUX) assay. Estrogen glucuronides in urine obtained from human males and females were effectively converted to active forms after incubation with beta-glucuronidase or E. coli. The highest estrogenic activity was found in deconjugated metabolites from urine of a pregnant woman, in which levels up to 3,000 nmol estradiol equivalents per liter of urine were found after overnight incubation of urine with E. coli. Bile sampled from male bream and flounder from various freshwater and marine locations was also deconjugated and a good correlation was found between high biliary estrogenic activity and elevated levels of xenoestrogenic activity in surface water as well as in plasma vitellogenin. Therefore, the measurement of deconjugated bile could form a useful (indirect) biomarker for internal dose of xenoestrogens in male fish.