Female Bream Research Articles

Polychlorinated Biphenyls in the Bream <i>Abramis brama</i> from the Volga Ples the Rybinsk Reservoir: Fish Age Effect and Human Health Risk Assessment

Bream, Abramis brama (L.), is an important commercial species and the object of monitoring pollution of freshwater bodies with polychlorinated biphenyls (PCBs). However, the dependence of the PCB content on the age of the bream has been studied very poorly. In this regard, the concentrations of 32 PCB congeners were measured in the carcasses of female bream of different ages in the pre-spawning period. It is shown that the concentration of PCBs in the body lipids increases from 257 to 449 ng/g over a period of 8 to 19 years. In terms of wet weight, the concentration of PCBs increases from 19.8 to 57.9 ng/g over a period of 8 to 13 years and then decreases to 21 ng/g at the age of 19 years. The largest share was 5-XB – from 46 to 58%, then 6-XB – from 17 to 29%, 4-XB – from 12 to 18%, 3-XB – from 4 to 8%, 7-XB – from 4 to 6% and 2-XB – from 0.1 up to 0.5%. PCB concentrations 5/8, 28, 31, 44, 49, 52, 74, 70/76, 87/115, 95/66 do not depend on age (R2 0.5); PCBs 97, 99, 105, 90/101, 110, 118. They have an average dependence (0.5 R2 0.6); PCBs 138, 153, 180, 183, 128/167 and 170/190 strongly depend (R2 ≥ 0.7). With age, the congener composition changes towards an increase in highly chlorinated PCBs. The content of PCBs in the carcass of bream of the Volga Ples of the Rybinsk reservoir does not exceed the existing in Russia MPC in fish, amounting to 2 mg/kg of raw weight. The average indicator of non–carcinogenic risk exceeds 1 (0.82–2.39), which indicates the possible development of non-carcinogenic diseases in target organs and systems. The indicator of carcinogenic risk exceeds the level of negligible risk (1 × 10–6) and corresponds to the range 2 – the maximum permissible risk or the upper limit of acceptable risk (1 × 10–6–1 × 10–4). These risks are subject to constant monitoring, the population is recommended to limit the consumption of large fish with a high fat content.

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.

Annual development cycle of gonads of bream (Abramis brama L. 1758) females from the lower Oder River sections influenced differently by the heated effluents from a power station

Gonads of female bream from three locations with varied temperature-influenced water from power plant cooling water effluents were analysed: (i) from the Oder River (above Gryfino, with no influence of the post-cooling water effluents from the ‘Dolna Odra’ power plant, NW Poland), (ii) from Lake Dąbie, below the canal receiving the heated effluents from the power station, and (iii) from downstream the effluent canal. Histological analysis indicated that in ambient conditions, the spawning season began at the study sites at the end of April and lasted through May and part of June. The initiation of gonad restoration (beginning of vitellogenesis, stage 3) was observed at the end of July, both in the Oder River and Lake Dąbie, and lasted throughout September. The gonads were at stage 4 in males from October to April and, in a few females, to May. The annual cycle of gonad development was similar in the female bream from both sites. The microscopic images of the oocytes were in the previtellogenesis and vitellogenesis at the two sites. The maximum diameter of the oocytes from the Oder was 909.7 μm, while oocyte diameter of fish from Lake Dąbie was 1018.4 μm. Oocytes not expelled during spawning season (May to August) were seen to undergo atresia. Female gonads from the heated effluent canal did not show any anomalies and the oocytes from the few fish caught in the winter were similar to those from the breams in other locations. Adult bream avoided excessive temperatures in the power plant effluent canal in the spring and summer, whereas juveniles were found in great numbers. In the spring, no female bream with mature gonads were caught in the cooling water effluent canal.

Suppression of aromatase activity in populations of bream ( Abramis brama) from the river Elbe, Germany

Aromatase activity was determined in brain and gonads of wild bream collected along the river Elbe, Germany, and correlated with other endocrine and reproductive endpoints such as plasma sex steroid concentrations, secondary sex characteristics (STI), plasma vitellogenin, gonad size (GSI), and maturation stages of germ cells (MS) that were reported for the same fish in a previous study. Furthermore, regional patterns of aromatase activity were correlated to a number of environmental factors such as exposure to environmental contaminants and parasitism. While aromatase activity was not detectable in the gonads of male and female fish with the assay used, fish of both genders revealed relatively great brain enzyme activities. As for most of the endocrine and reproductive parameters, with the exception of plasma testosterone (T), aromatase activities were significantly less in fish from a river stretch characterized by elevated exposures to organic contaminants and metals. Brain aromatase activity was positively and significantly correlated with plasma estradiol (E2) and MS in females, and showed a similar trend with plasma 11-ketotestosterone (11KT) and STI in males. No comparable trend occurred for T. This decrease of the reproductively relevant hormones 11KT and E2 may be indicative of a disruption of the last step in sex hormone synthesis, a hypothesis that was supported for E2 by the strong ( R 2 = 0.78, p < 0.05) linear regression between aromatase activity and E2 in female bream. It is also hypothesized that the effects on brain aromatase activity were likely to be related to the disruption of other reproductive parameters including sexual maturity and expression of secondary sex characteristics. Although a number of factors such as exposure to pollutants and prevalence of the tapeworm Ligula intestinalis correlated with the suppression of aromatase activity, the exact causes for the regional decrease in brain aromatase activity remain unclear due to inconsistencies of these correlations between sampling events or gender.

Parasitism in fish—an endocrine modulator of ecological relevance?

Wild bream ( Abramis brama) were collected from the river Elbe, and the influences of parasitic infection by the tapeworm Ligula intestinalis on endocrine and related functions (vitellogenin [VTG]; plasma sex steroids: 17β-estradiol [E2], 11-ketotestosterone [11-KT] and testosterone [T]; relative gonad [GSI] and liver [HSI] growth; maturation stages of germ cells [MS]; prominence of spawning tubercles [STI]) were investigated. Distinct regional differences in infection rates of bream with L. intestinalis were observed along the Elbe with the highest prevalences at the Czech border (up to 45%) and Magdeburg (up to 65%), areas that are heavily contaminated with complex mixtures of organic chemicals and metals. Parasitized fish of both sexes had significantly lower GSIs and poorly developed gonads (low MS). In males, a significant reduction in the prominence of spawning tubercles occurred. Infected females had significantly lower plasma VTG concentrations. A selective suppression of the sex steroids 11-KT and E2 was observed in male and female bream, respectively. Testosterone was not affected in the same manner in fish of both sexes. At sites with an elevated prevalence of L. intestinalis, the extent of the infection of an individual was significantly correlated with the suppression of the measured biomarkers. However, when applying a linear model to compare regional differences in infection prevalence with biological parameters, not all of the observed differences could be explained by parasitization by L. intestinalis. This indicates that other factors such as pollution may have contributed to the effects on reproductive and endocrine processes that occurred along the river. Given that sites with high prevalences of L. intestinalis were also characterized by elevated pollution, it is possible that there exists a combinatory effect of both pollution and parasitization that can have a serious impact on the reproductive capacity of a population, such as was observed at the sampling site at Magdeburg.

The biology of bream, Abramis brama (L), and its natural hybrid with roach, Rutilus rutilus (L), in the River Exe

Hybrids between bream, Abramis brama, and roach, Rutilus rutilus, occur in the lower reaches of the River Exe and were positively identified by their meristic features and shape of the pharyngeal bone. The growth of bream and hybrids was determined by back‐calculation from scales. Annual checks were laid down in early June. The mean length for age of female bream was significantly larger than that of males for fish 6 years of age and older. This divergence in growth rate was associated with the sexual maturation of the fish. Data for the sexes were combined and compared with the growth rate of hybrids and roach from the same region. Hybrid growth was similar to that of bream for the first 6 years of life but was intermediate between that of the two parent species in the older age groups. Some hybrids with developing gonads were found. A change in the diet of bream from planktonic feeding to a benthophagic habit with age was noted. Detritus, substrate and chironomid larvae formed the bulk of the diet of hybrids.