Male Roach Research Articles

Influence of group size on shelter choice in Blaptica dubia cockroaches.

Individuals in social groups can gain benefits from being in those groups, including an increased ability to find food and avoid predators. We tested for potential group benefits in shelter choice in the Argentinian wood roach, Blaptica dubia. Roaches were tested in arenas with two shelters available in which one shelter was significantly darker than the other. Female and male roaches, housed separately, were tested as solitary individuals, or in same-sex groups of 5, 10, or 15. The roaches were tested under two light regimes (lights on vs. lights off) and two shelter distances (shelters near vs. shelters far) to provide variation in shelter search conditions. Solitary individuals chose the darker shelter at chance levels, but the roaches in groups chose the darker shelter significantly more often than chance. Furthermore, the two largest groups chose the darker shelter more often than the group of five roaches. We detected effects related to light variation that indicated roaches were more likely to be under either shelter in the lights-on conditions, and more likely to be out in the arena and under no shelter in the lights-off condition. Shelter distances had negligible effects on shelter choice and sex had no effect. Taken together, our results indicate individuals can make more optimal choices regarding shelter darkness if they are in a group, and that decision-making related to shelter is sensitive to variation in social context. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Endocrine disruption effects in male and intersex roach (Rutilus rutilus, L.) from French rivers: An integrative approach based on subcellular to individual responses.

Among the chemicals found in the aquatic environment, some have been reported to interact with the endocrine system of organisms and have been identified as endocrine disrupting compounds. In this study, we have assessed the biological effects due to environmental estrogenic compounds in adult male roach (Rutilus rutilus). Wild fish were collected in the Seine River, and one of its affluent, the Epte River in Normandy, France and impacts on endocrine and reproductive functions have been assessed. This study provides innovative data on the intersex condition in wild fish that are crucial to understand estrogenic contamination impacts and maintenance of sustainable fish population. The biomarker responses found in fish from contaminated sites included high plasmatic vitellogenin concentrations, altered steroid levels, histopathological and up to 50% intersex fish among the male. However, the overall sex ratio of the roach population indicated sign of feminization with some sites showing only 20% of males. The chemical organic contamination at the different location sites has been characterized by the levels of PAHs, PCBs and phthalates and total estrogenic activity was measured by the YES in vitro assay.

The effect of diet on the metabolic rate and microbiome of Gromphadorhina portentosa

The metabolic phenotype of an animal is shaped by the developmental trajectory of its gut microbiome. Although the core microbiota of an organism is stable throughout adulthood, there are certain parts of the microbiome that can be altered through an array of environmental stressors, such as diet. So far, there is a lot of research focused on the effects that diet has on the metabolism and gut microbiome of vertebrate mammals. However, not a lot of work is focused on how a change in diet can affect the metabolic rates, or the microbiome, of invertebrates. In its natural habitat Gromphadorhina portentosa, the hissing cockroach, feeds opportunistically on fruits and may also consume decaying animal material and small insects. In this study we measured the effects of diet on the metabolic rate, and microbiota, of G. portentosa. Prior to data collection we normalize the microbiota of forty male cockroaches by placing them on a control diet. Preliminary data showed that roaches would move all gut contents through their digestive system within 7 days. Resting metabolic rates for normalized cockroaches was measured after cockroaches had been placed for 2 weeks under the control diet. Fecal samples were also collected at this time. Ten male roaches were placed under one of four diet treatments (control, high protein, high carbohydrate or high lipid) for a total of 8 weeks. During this experimental period, resting metabolic rates were obtained on a weekly basis using flow through respirometry. Fecal samples were once again collected at the end of the 8‐week experimental period. Cultivation independent metagenomic sequencing was accomplished so that changes in the microbiota of roaches could be identified. Previous work has shown a shift in the microbiota of organisms fed varying amounts of fat vs. protein, were animals fed a high protein diet showed an increase in bacteroidetes with was an inverse relationship to the firmicute population. Furthermore, an increase in metabolic rates have also been seen when animals are given a high protein diet. We expect G. portentosma to respond in a similar manner when their diet is altered.Support or Funding InformationULV Faculty Research Grant

Effects of Exposure to WwTW Effluents over Two Generations on Sexual Development and Breeding in Roach Rutilus rutilus.

Exposure to environmental estrogens in wastewater treatment works (WwTW) effluents induces feminized responses in male fish, including the development of eggs in male testes. However, the impacts on the offspring of exposed fish are not well understood. In this study, we examined whether roach (Rutilus rutilus) from mothers that had been exposed to an undiluted WwTW effluent from early life to sexual maturity had altered susceptibility to gonadal feminization and an impaired capacity to reproduce. For males from both WwTW effluent exposed mothers and dilution water exposed mothers, effluent exposure for up to 3 years and 9 months induced feminized male gonads, although the intersex condition was relatively mild. There was no difference in the severity of gonadal feminization in roach derived from either WwTW effluent exposed or dilution water exposed mothers. Furthermore, a breeding study revealed that roach with effluent-exposed mothers reproduced with an equal success as roach with mothers exposed to clean water. Roach exposed to the effluent for 3 years in this study were able to reproduce successfully. Our findings provide no evidence for impacts of WwTW effluent exposure on reproduction or gonadal disruption in roach down the female germ line and add to existing evidence that male roach with a mild intersex condition are able to breed competitively.

Metabolomics Reveals Target and Off-Target Toxicities of a Model Organophosphate Pesticide to Roach (Rutilus rutilus): Implications for Biomonitoring

The ability of targeted and nontargeted metabolomics to discover chronic ecotoxicological effects is largely unexplored. Fenitrothion, an organophosphate pesticide, is categorized as a “red list” pollutant, being particularly hazardous to aquatic life. It acts primarily as a cholinesterase inhibitor, but evidence suggests it can also act as an androgen receptor antagonist. Whole-organism fenitrothion-induced toxicity is well-established, but information regarding target and off-target molecular toxicities is limited. Here we study the molecular responses of male roach (Rutilus rutilus) exposed to fenitrothion, including environmentally realistic concentrations, for 28 days. Acetylcholine was assessed in brain; steroid metabolism was measured in testes and plasma; and NMR and mass spectrometry-based metabolomics were conducted on testes and liver to discover off-target toxicity. O-demethylation was confirmed as a major route of pesticide degradation. Fenitrothion significantly depleted acetylcholine, confirming its primary mode of action, and 11-ketotestosterone in plasma and cortisone in testes, showing disruption of steroid metabolism. Metabolomics revealed significant perturbations to the hepatic phosphagen system and previously undocumented effects on phenylalanine metabolism in liver and testes. On the basis of several unexpected molecular responses that were opposite to the anticipated acute toxicity, we propose that chronic pesticide exposure induces an adapting phenotype in roach, which may have considerable implications for interpreting molecular biomarker responses in field-sampled fish.

Implications of Persistent Exposure to Treated Wastewater Effluent for Breeding in Wild Roach (Rutilus rutilus) Populations

Feminized responses are widespread in wild populations of roach, Rutilus rutilus, living in UK rivers, and some of these responses have been shown to arise as a consequence of exposure to wastewater treatment works (WwTW) effluent discharges and the endocrine disrupting chemicals (EDCs) they contain. The causation of the ovotestis condition in wild roach, however, has yet to be established. Furthermore, the impact of long-term exposure to WwTW effluents on the reproductive fitness of wild fish populations is not known, and this information is crucial for population level effect assessments. We undertook a chronic exposure of roach to a treated estrogenic wastewater effluent for up to 3.5 years to assess principally for effects on subsequent reproductive fitness, as determined through parentage analysis on offspring from a competitive breeding study. In generating the fish for the breeding study we found that exposure to full strength WwTW effluent until sexual maturity resulted in sex reversal in almost all males in the population; 98% of the exposed fish were phenotypic females, containing ovaries. Furthermore, fish exposed to a 50% dilution of WwTW effluent contained ovotestis (21% of the male roach) that was absent from the control population. In competitive breeding studies, and applying DNA microsatellites to assess parentage, we show that presumptive females exposed to sexual maturity to WwTW effluent bred normally, albeit in the absence of nonexposed females, but putative sex-reversed males breeding as females contributed poorly, if at all, in a breeding population, depending on the competition. These novel findings on sex reversal add a new dimension for impact assessments of exposure to WwTW effluents on fish populations.

Inhibition of gametogenesis by the cestodeLigula intestinalisin roach (Rutilus rutilus) is attenuated under laboratory conditions

Reproductive parameters of Ligula intestinalis-infected roach (Rutilus rutilus) which were held under long-tem laboratory conditions with unlimited food supply were investigated. Although uninfected and infected roach showed no difference in condition factor and both groups deposited perivisceral fat, the gonadosomatic-index was significantly lower in infected female and male roach. Quantitative histological analysis revealed that gonad development was retarded upon parasitization in both genders. In contrast to the phenotype described in the field, infected females were able to recruit follicles into secondary growth, but a high percentage of secondary growth follicles underwent atresia. In both genders, the histological data corresponded well with reduced expression of pituitary gonadotropins and lowered plasma concentrations of sex steroids, as revealed by real-time RT-PCR and ELISA, respectively. Furthermore, a reduction of vitellogenin mRNA and modulated expression of sex steroid receptors in the liver was demonstrated. Like in the field, there was a significant adverse impact of L. intestinalis on host reproductive physiology which could not be related to parasite burden. Our results show, for the first time, that maintenance under laboratory conditions can not abolish the deleterious effect of L. intestinalis on gametogenesis in roach, and indicate a specific inhibition of host reproduction by endocrine disruption.

Roach (Rutilus rutilus) reproductive cycle: a study of biochemical and histological parameters in a low contaminated site

Fish reproduction is subjected to worrying trends in many aquatic environments. In this study, we report the absence of histological and biochemical alterations in fish sampled in a low contaminated site (characterised by the absence of detectable oestrogenic activity and mutagenicity in sediment extracts). A total of 474 roach (Rutilus rutilus) were monthly sampled during 18 months, and no intersex fish were recorded after careful histological examination, thus indicating that the incidence of this phenomenon may be very low under natural conditions. Furthermore, mean male plasma vitellogenin concentration was 24 ng ml(-1) and was only slightly elevated during the spawning period (up to 120 ng ml(-1)) indicating that these low values may be characteristic of a low contaminated site. Of the male roach, 45.3% were sampled, a sex-ratio that did not significantly deviated from the expected 1:1 ratio between male and female. Results also showed that natural conditions can greatly affect the reproductive cycle of roach. Gametogenesis showed a biphasic pattern with first gonad maturation between September and December and a final maturation occurring at the end of winter/early spring. Under decreasing temperatures, particularly below 6 degrees C, gametogenesis was stopped or even regressed with secondary oocytes becoming rare under histological observation. Conversely, elevated temperatures during the winter lead to an earlier gonad maturation.

Seasonal variations and alterations of sex steroid levels during the reproductive cycle of male roach ( Rutilus rutilus)

Seasonal variations of plasma steroid concentrations i.e. progesterone (P), 11-ketotestosterone (11-KT) and 17-β-estradiol (E2) were determined immunoenzymatically during a whole reproductive cycle in male roach ( Rutilus rutilus) caught in a reference site. Plasma 11-KT concentrations were significantly correlated with gonad growth, expressed as the gonado-somatic index ( R 2 = 0.60; p < 0.05) and highest concentrations (757 ± 99 pg ml −1) coincided with the final testis maturation in March. E2 and P concentrations peaked once during the reproductive cycle. E2 synthesis was significantly induced during the spawning period while P concentration peaked at the very start of the gametogenesis (June) thus suggesting specific roles of these steroids in the reproductive cycle. Comparison of reference levels were then made with plasma steroid concentrations from male roach sampled in polluted areas in the North of France. A significant decrease of E2 (50–60%) and 11-KT (76–84%) was measured, indicating that endocrine disrupting compounds may have interfered with the normal sex steroid synthesis. Contrary to the E2 and 11-KT sex steroids, plasma P concentration was not significantly affected in fish inhabiting impacted areas.

Growth rate during early life affects sexual differentiation in roach (Rutilus rutilus)

Many environmental factors have been shown to influence sex differentiation in fish, resulting in sex-biased populations, but the effects of growth rate have received limited attention. We conducted a controlled laboratory experiment in which growth rate and population density were manipulated in roach (Rutilus rutilus) during early development, and the subsequent effects on sex ratio determined. Significant differences in growth rate between fish populations were induced through provision of three different ration levels. In the slowest growing population there were fewer females compared within the fastest growing population (19% compared to 36% females), suggesting that in roach it may be more advantageous to become a small male than a small female when growth potential is limited. This may result from the fact that fecundity is limited by body size in female roach and that male roach are able to reproduce at a significantly smaller body size than females. In contrast, where roach were kept at different stocking densities, and there were no differences in growth rate, the subsequent proportion of females did not vary. Our data highlight the importance of controlling for growth rate in research on sexual differentiation in this species, notably when assessing for the effects of endocrine disrupting chemicals and other environmental factors, and have implications for fisheries management and aquaculture. The underlying mechanism for the influence of growth rate on sex differentiation has yet to be determined but is likely to have a strong endocrinological basis.

The Yin and Yang of Exposure: Chemical Combinations May Explain Feminization of Wild Fish

Vol. 117, No. 5 EnvironewsOpen AccessThe Yin and Yang of Exposure: Chemical Combinations May Explain Feminization of Wild Fish Julia R. Barrett Julia R. Barrett Search for more papers by this author Published:1 May 2009https://doi.org/10.1289/ehp.117-a211aAboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail More than 100,000 substances occur in wastewater effluent, including an array of endocrine disruptors such as human and veterinary pharmaceuticals, natural and synthetic hormones, detergents, and industrial chemicals. Studies have linked estrogenic wastewater pollution with feminization of males in downstream fish populations. However, findings from rodent models of testicular dysgenesis syndrome, a spectrum of environmentally linked male reproductive disorders in humans, indicate that both estrogens and antiandrogens may be contributing to health effects in tandem. A new study that models exposure to both estrogenic and antiandrogenic compounds in wild fish now suggests that combinations of these compounds, rather than estrogenic compounds alone, may be responsible for the endocrine disruption observed in these animals as well [EHP 117:797–802; Jobling et al.].To help elucidate the complex relationships and interactions among the various types of endocrine disruptors (estrogenic, anti-estrogenic, androgenic, and antiandrogenic), the authors created statistical models based on 1) the chemicals’ known hormonal activities in recombinant yeast screen assays and 2) concentrations measured during an earlier national survey in effluent from U.K. wastewater treatment plants. The models also included hydrologic data to enable estimation of river-water chemical concentrations at specific sites and national survey data on the location and prevalence of feminized male fish. The statistical models first accounted for estrogenic effects observed in fish, then included effects associated with antiandrogens and other compounds.The authors previously found a very strong correlation between the predicted steroid estrogen content of U.K. rivers and feminization in male wild fish. In the current study they focused on four specific traits of feminization: elevated plasma levels of vitellogenin (an egg yolk precursor protein normally produced only in females), feminized reproductive ducts, oocyte (egg cell) development in the testes, and the number of oocytes found in the testes. Once the main factors accounting for variation were identified, the researchers were able to distinguish the respective contributions of estrogens and antiandrogens to biologic responses and explore potential interactions.Model estimates suggested that male fish exposed to the highest concentrations of estrogens or antiandrogens were the most likely to be feminized. However, chemical combinations were also important. Estrogens and antiandrogens acted additively with regard to oocytes in the testes, but estrogens appeared to antagonize effects of antiandrogens on feminization of the reproductive duct. The authors note that combined effects were not necessarily due to simultaneous exposure; for example, one compound could serve as an initiator early in life while another could act as a promoter later in life. On the basis of these analyses, the authors suggest that sexual disruption in male wild fish populations may be related to exposure to a combination of both estrogenic and antiandrogenic compounds, a relationship that may also hold true for humans.The micrograph on the left shows normal testis tissue from an adult male roach (Rutilis rutilis). On the right is the testis of a severely feminized male roach; the large circular inclusions are oocytes.FiguresReferencesRelatedDetails Vol. 117, No. 5 May 2009Metrics About Article Metrics Publication History Originally published1 May 2009Published in print1 May 2009 Financial disclosures License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

Roach, Sex, and Gender-Bending Chemicals: The Feminization of Wild Fish in English Rivers

Feminization of the male roach, Rutilus rutilus, a freshwater, group-spawning fish, is widespread in English rivers; among the causative agents are natural and synthetic steroidal estrogens and chemicals that mimic estrogens. In feminized male roach, concentrations of the egg-yolk protein vitellogenin are elevated, sex steroid hormone dynamics are altered, and gonad development is disrupted (most notably, a female reproductive duct or developing eggs [oocytes] are present in the testis). In some English rivers containing high levels of estrogens, all male roach sampled have been feminized to varying degrees. In the more severely affected males, individuals produce low-quality sperm with a reduced capability for fertilization. Laboratory studies have shown that the environmental estrogens responsible for inducing gonadal feminization in roach can also alter reproductive behavior, disrupting normal breeding dynamics (parentage) in the zebrafish, another group-spawning fish. Together these findings indicate ...

The effects of treated effluents on the intensity of papillomatosis and HSP70 expression in roach

Epidermal papillomatosis in fish has been proposed as an indicator of environmental stress but experimental evidence of connection between contaminants and papillomatosis in fish is scarce. We studied changes in the intensity of epidermal papillomatosis and the expression of heat shock protein 70 (HSP70) in roach, Rutilus rutilus, exposed to treated pulp mill and municipal effluents. In male roach, the increase in papillomatosis intensity was higher in fish exposed to 15% than in fish exposed to 1.5% concentration of municipal effluent. No differences were observed in papillomatosis development in females, or in HSP70 expression. In all the experiments conducted, the increasing effect of effluents seemed to be more pronounced in male fish suggesting that sex-related factors affected the intensity of papillomatosis after exposure to effluents. The present results indicate that environmentally relevant concentrations of municipal effluents may be contributing to the development of papillomatosis in fish.

Hypoxia increases intensity of epidermal papillomatosis in roach Rutilus rutilus

Hypoxia, which occurs frequently in aquatic ecosystems and is mainly due to increasing eutrophication can cause severe environmental stress in fish. We investigated experimentally the hypothesis that hypoxia could be one of the environmental stress factors that can induce papillomatosis in fish. Male roach Rutilus rutilus exposed to periodic oxygen deficiency and accompanied temperature increases (OT group) showed the highest increase in the intensity of papillomatosis, as measured by the number of scales covered by papillomatosis tumors. The second highest increase in disease intensity was among male roach exposed to periodical temperature increases. The incidence of such tumors was lowest in the control group, which was exposed to neither hypoxia nor increased temperature. The mortality of fish during the 17 d experiment was highest and the condition factor was lowest in the OT group, indicating this group experienced a higher level of stress. The apparent interaction of hypoxia and temperature suggests that these environmental stressors are among the multifactorial elements leading to papillomatosis in roach. Furthermore, these results provide experimental evidence to indicate that hypoxia may contribute to tumor development in fish.

Functional Associations between Two Estrogen Receptors, Environmental Estrogens, and Sexual Disruption in the Roach (Rutilus rutilus)

Wild male roach (Rutilus rutilus) living in U.K. rivers contaminated with estrogenic effluents from wastewater treatment works show feminized responses and have a reduced reproductive capability, but the chemical causation of sexual disruption in the roach has not been established. Feminized responses were induced in male roach exposed to environmentally relevant concentrations of the pharmaceutical estrogen 17alpha-ethinylestradiol, EE2 (up to 4 ng/ L), during early life (from fertilization to 84 days posthatch, dph), and these effects were signaled by altered patterns of expression of two cloned roach estrogen receptor (ER) subtypes, ERalpha. and ERbeta, in the brain and gonad/ liver. Transactivation assays were developed for both roach ER subtypes and the estrogenic potencies of steroidal estrogens differed markedly at the different ER subtypes. EE2 was by far the most potent chemical, and estrone (E1, the most prevalent environmental steroid in wastewater discharges) was equipotent with estradiol (E2) in activating the ERs. Comparison of the EC50 values for the compounds tested showed that ERbeta was 3-21-fold more sensitive to natural steroidal estrogens and 54-fold more sensitive to EE2 as compared to ERalpha. These findings add substantial support to the hypothesis that steroidal estrogens play a significant role in the induction of intersex in roach populations in U.K. rivers and that the molecular approach described could be usefully applied to understand interspecies sensitivity to xenoestrogens.

Health Effects in Fish of Long-Term Exposure to Effluents from Wastewater Treatment Works

Concern has been raised in recent years that exposure to wastewater treatment effluents containing estrogenic chemicals can disrupt the endocrine functioning of riverine fish and cause permanent alterations in the structure and function of the reproductive system. Reproductive disorders may not necessarily arise as a result of estrogenic effects alone, and there is a need for a better understanding of the relative importance of endocrine disruption in relation to other forms of toxicity. Here, the integrated health effects of long-term effluent exposure are reported (reproductive, endocrine, immune, genotoxic, nephrotoxic). Early life-stage roach, Rutilus rutilus, were exposed for 300 days to treated wastewater effluent at concentrations of 0, 15.2, 34.8, and 78.7% (with dechlorinated tap water as diluent). Concentrations of treated effluents that induced feminization of male roach, measured as vitellogenin induction and histological alteration to gonads, also caused statistically significant alterations in kidney development (tubule diameter), modulated immune function (differential cell count, total number of thrombocytes), and caused genotoxic damage (micronucleus induction and single-strand breaks in gill and blood cells). Genotoxic and immunotoxic effects occurred at concentrations of wastewater effluent lower than those required to induce recognizable changes in the structure and function of the reproductive endocrine system. These findings emphasize the need for multiple biological end points in tests that assess the potential health effects of wastewater effluents. They also suggest that for some effluents, genotoxic and immune end points may be more sensitive than estrogenic (endocrine-mediated) end points as indicators of exposure in fish.

Prelude to Intersex in Fish: Identifying a Sensitive Period for Feminization

Field studies have shown a high occurrence of intersex (the presence of both male and female characteristics) and ovotestis (the presence of eggs in the testis) in wild populations of a fish known as roach (Rutilus rutilus) in rivers in the United Kingdom that are downstream from wastewater treatment plants. Furthermore, studies have demonstrated that intersex males are less fertile, which may have population-level effects. However, to date, scientists have been unable to induce intersex in male fish with controlled exposures to wastewater effluents. A study conducted at The University of Exeter now shows that the sensitive period for feminization of the reproductive duct—in which the male testis forms an ovary-like cavity—may occur earlier than previously thought, and raises new questions about the conditions that lead to actual germ cell disruption [EHP 113:1299–1307]. Many questions persist about the causes of and the most vulnerable life stages for various types of sexual effects induced by estrogenic chemicals in wastewater effluent. In this study, the researchers collected two different U.K. wastewater effluents and exposed wild roach at two life stages: during early life and development of the gonads (from fertilization up to 300 days post-hatch) and as adults producing germ cells following annual spawning. These adults included one group of fish that had been raised in clean water and another that had hatched and grown to maturity in the wild. Both effluents induced synthesis of vitellogenin (an estrogen-dependent yolk precursor and biomarker of estrogen exposure) at both life stages, with the extent of this induction correlating with the steroid estrogen content of the effluent. Previous studies have demonstrated that feminization of the sperm duct to form an ovary-like cavity occurs when exposure to effluent comes during the time of sexual differentiation, which in roach occurs from 50 to 150 days post-hatch. This study showed alteration of the sperm duct with an exposure earlier in life, from fertilization to 60 days post-hatch, before any signs of sexual development appear. The alteration, furthermore, was permanent, persisting even after 240 days’ maintenance in clean water after exposure. However, no ovotestis was observed in any of the juvenile fish. There was also no evidence of ovotestis in post-spawning adult male roach raised in a clean environment and subsequently exposed to effluent. There was evidence that the wild males had previously been exposed to estrogenic stimuli, as some of males had ovotestis when the study began. The severity of this condition increased slightly during the study period, but the increase occurred across both exposed and control fish and thus appeared unrelated to the study effluent exposure. The authors suggest possible explanations that need further study—one is that ovotestis is induced only by effluents with greater levels of estrogenic chemicals than those used in the study. The researchers evaluated the effluents for content of two chemicals previously implicated in causing intersex—steroidal estrogens and alkylphenols—and found that these levels were similar to concentrations reported in wastewater effluents in the United Kingdom and worldwide. They emphasize that chemical content and interactions ideally should be taken into account when trying to determine the conditions that lead to sexual effects. The results of these studies raise the possibility that ovotestis may be a result either of longevity of exposure or of programming in early life that manifests itself as fish mature sexually. Previous findings from the authors support this idea by showing that the severity of intersex increases with age. The authors are further exploring these possibilities now with a laboratory study of roach that includes an environmentally relevant estrogen exposure of two years’ duration.

Intersex in wild roach ( Rutilus rutilus) from Danish sewage effluent-receiving streams

Roach ( Rutilus rutilus) from Danish streams that receive discharges of domestic sewage effluent were examined for the presence of alterations to gonadal development. In male roach, intersex was observed at a prevalence of 4.5–5% at reference sites and 6.7–6.5% at sewage effluent-impacted sites. A positive correlation was found between sewage effluent load and intersex frequency among male roach. The highest frequency of intersex (26.5%) was found in the stream Kristrup Landkanal, which had the highest percentage and load of sewage effluent (87,578 population equivalents). Further, a tendency to an average higher severity of the phenomenon (calculated as an intersex index value) was seen in males from streams impacted by sewage effluent compared to males from reference sites. However, this was significant only in male fish from Egaa Brook. Among roach from the Kristrup Landkanal 5.8% of male and 0.8% of female roach were infected with the parasite Pleistophora mirandellae, causing degenerative changes in testes and ovaries. No correlation was seen between the intersex condition and the presence of P. mirandellae in the gonads of roach.

Accounting for Differences in Estrogenic Responses in Rainbow Trout (Oncorhynchus mykiss: Salmonidae) and Roach (Rutilus rutilus: Cyprinidae) Exposed to Effluents from Wastewater Treatment Works

Effluents from wastewater treatment works (WwTWs) contain estrogenic substances that induce feminizing effects in fish, including vitellogenin (VTG) synthesis and gonadal intersex. Fish vary in their responsiveness to estrogenic effluents, but the physiological basis for these differences are not known. In this study, uptake of estrogen from two WwTW effluents (measured in hydrolyzed bile) and estrogenic response (VTG induction) were compared in a salmonid (rainbow trout, Onchorhynchus mykiss) and a cyprinid fish (roach, Rutilus rutilus). Immature rainbow trout were more responsive than maturing roach to the estrogenic effluents. The more potent of the two estrogenic effluents (containing between 24.3 and 104.1 ng estradiol-17beta equivalents/L [E2eq/L]) resulted in a 700-fold and 240-fold induction of plasma VTG in male and female trout, respectively, but only a 4-fold induction in roach (and in males only). The less potent effluent (varying between 4.1 and 6.8 ng E2eq/L) induced VTG in the trout only, with a 4-fold and 18-fold induction in males and females, respectively. In fish exposed to tap water, the estrogenicity of the hydrolyzed bile was 0.03+/-0.01 ng E2eq/microL (for both sexes in trout), 0.18+/-0.04 ng E2eq/microL in male roach, and 0.88+/-0.15 ng E2eq/microL in female roach. The higher bile content of estrogen in control roach reflected their more advanced sexual status (and thus higher endogenous estrogen) compared with the immature female trout. In trout maintained in effluents, the bile content of estrogen was 100-fold and 30-fold higher than controls at WwTW A and B, respectively. Bioconcentration factors (BCFs) for estrogenic activity in bile were between 16 344 and 46 134 in trout and between 3543 and 60 192 in roach (no gender differences were apparent). There were strong correlations between VTG induction and the estrogenic activity of bile extracts for both trout and roach. The results confirm that estrogenic contaminants bioconcentrate to a high degree in fish bile and that the level (and nature) of this accumulation may accountfor responsiveness to the endocrine disruptive effects of estrogenic effluents. Immature fish were the more appropriate life stage for quantifying estrogen exposure and uptake in bile, as they contain little circulating endogenous oestrogen compared with sexual maturing fish. The nature of the estrogenic contaminants is detailed in an accompanying paper.

In vitro embryo survival and early viability of larvae in relation to male sexual ornaments and parasite resistance in roach, Rutilus rutilus L.

According to the 'good genes' hypothesis, sexual ornaments provide an indication of the 'quality' of the bearer. In roach, Rutilus rutilus, breeding tubercles (BTs) may signal resistance against the digenean parasite, Rhipidocotyle campanula. Life history theory predicts that there should be a trade-off between parasite resistance and other life history traits. In roach, this could imply a trade-off between parasite resistance in mature fish and some larval feature. We studied embryo survival and the early viability of larvae of male roach in relation to expression of BTs and parasite resistance in maternal half-sibling families. Highly ornamented males had higher resistance against R. campanula than less ornamented males, but the BTs were not related to either embryo survival or larval viability. However, sires having higher resistance to R. campanula had lower larval viability. These results suggest that BTs of male roach do not indicate 'quality' in terms of early survival or viability, but rather in terms of adult parasite resistance.