Roach Populations Research Articles

Long-term decline of whitefish (Coregonus lavaretus) population in the boreal lake Pyhäjärvi, southwest Finland, relative to simultaneous abiotic and biotic changes

In recent decades many lake fish populations have faced complex pressures particularly due to climate warming and eutrophication. In Lake Pyhäjärvi, southwest Finland, profound changes have occurred in the commercial winter fisheries targeting the coregonids vendace, Coregonus albula, and whitefish, Coregonus lavaretus. The responses of vendace have been examined earlier, and here the detailed analyses are extended to the whitefish. In the 1970s and 1980s, the coregonid fishery was sustainable, but in 1991–1998, intense exploitation led to recruitment overfishing of vendace. Despite temporarily improved growth and recruitment of whitefish during vendace decline, whitefish population biomass declined throughout the study period, while perch (Perca fluviatilis), roach (Rutilus rutilus) and ruffe (Gymnocephalus cernuus) increased and vendace and smelt (Osmerus eperlanus) maintained their abundance. As many other northern lakes, Pyhäjärvi seems to be changing from coregonid to perch dominance due to climate warming and eutrophication. Whitefish decline was associated with decreases in fecundity, winter survival of embryos, and larval density. The spawning stock was kept small by intensive fishery. The decline of the relative fecundity was likely due to food competition with vendace and especially the perch and roach populations that increased with eutrophication and more frequent hot summers. The winter survival of whitefish embryos decreased when the introduced signal crayfish (Pacifastacus leniusculus) increased. Despite decreasing fishing effort in the 2000s the larval numbers continued to decline. In the prevailing circumstances in Pyhäjärvi, whitefish will with high probability remain as a minor and still declining species of the fish assemblage.

Temporal Variation of Genetic Diversity in Rutilus rutilus Populations from Lithuania Using mtDNA Markers in the Context of Anthropogenic Activities

One of the most abundant fish species, Rutilus rutilus, is widely distributed in Lithuania and its potential to adapt to environmental changes attracted our interest. Unfortunately, it is not properly understood how anthropogenic activities can affect the genetic diversity within this species. We studied three populations of roaches (samples collected in the Neris and Žeimena rivers, and Lake Drūkšiai) over a period of five years (from 2017 to 2022) to determine genetic diversity using mtDNA D-loop and ATP6 genetic markers. Genetic diversity parameters, AMOVA analysis, haplotype network, and PCoA analysis revealed a greater genetic variability in roach samples collected in 2017, and the greatest differences were noticed in the population inhabiting Lake Drūkšiai, as compared with other samples studied over a five-year period. Differences in genetic diversity detected after a five-year period led us to the assumption that roach populations may be related to the effects of natural (changing climatic conditions) and anthropogenic (operating nuclear power plant) origin.

ИСКУССТВЕННОЕ ВОСПРОИЗВОДСТВО ПОЛУПРОХОДНЫХ ВИДОВ РЫБ ПРИ РАЗНЫХ СЦЕНАРИЯХ РАЗВИТИЯ ГИДРОЛОГИЧЕСКОЙ ОБСТАНОВКИ В АЗОВСКОМ МОРЕ

Background. Semi-anadromous fish species of the Azov Sea were the primary fishing targets before the regulation of the flow of the Don and Kuban Rivers, after the anthropogenic transformation of which artificial reproduction became the main source of recruitment for the populations of these species of aquatic biological resources. Unprecedented climate-induced reduction in the volume of freshwater runoff in 2006–2023 aggravated the deterioration of the conditions for reproduction of anadromous fish species in the aquatic areas associated with fish feeding and rearing facilities and contributed to the decline of their feeding conditions in the sea resulting from a sharp increase in salinity, which led to a reduction in their population abundance. Relevance. In the context of a record reduction in freshwater runoff and increasing salinity of the Azov Sea, the Azov Sea ichthyocenosis undergoes a fundamental restructuring, which requires making a forecast of the possible changes in the habitat of semi-anadromous fish species, as well as evaluating the prospects for artificial reproduction of zander, roach and bream for their preservation in new conditions, which, in turn, serves as the aim of this work. Methods. To predict possible changes in the hydrological regime of the Azov Sea, the expert evaluation method has been used. The expert assessment of possible scenarios of the impact exerted by the modern climate change on the habitat of the aquatic biological resources in the Azov Sea has been done with the regard to the provisions of the Climate Doctrine of the Russian Federation. Results. Under all predicted scenarios for the period up to 2030, the salinity of the Azov Sea will exceed the values optimal for the juveniles and mature individuals of semi-anadromous fish species. Preservation of biologically valuable populations of zander and roach is possible with the continuous operation of hatcheries (spawning and rearing facilities), both in limans and on floodplain. To preserve the population and increase the stock of bream, it is necessary to restore artificial reproduction of this species. Conclusions. In the medium term (until 2030), only roach has a prospect for the sufficient recovery of its stocks, which could happen under the favorable hydrological scenario involving the water content increase in the basin. In all other cases, bream, zander and roach will not be in position to considerably increase their abundance.

Feminizing effects of ethinylestradiol in roach (Rutilus rutilus) populations with different estrogenic pollution exposure histories.

Experimental exposures aimed at assessing the risks posed by estrogens in waste-water treatment work (WwTW) effluents to fish populations have rarely considered whether populations differ in their sensitivity to estrogenic compounds. This is despite evidence that selection at genes involved in the estrogen response has occurred in wild populations, and evidence that genotype can influence estrogen-response. In this study we compare the effects of a two-year exposure to a low measured concentration (1.3 ng/L) of ethinylestradiol (EE2) on the sexual development of roach (Rutilus rutilus) whose parental generation was sampled from two river stretches heavily contaminated with WwTW effluent and from two without any known WwTW effluent contamination. Exposure to EE2 significantly reduced the proportion of genetic males and induced a range of feminized phenotypes in males. Significantly, exposure also increased the proportion of genetic females with vitellogenic oocytes from 51 to 96%, raising the possibility that estrogen pollution could impact populations of annually spawning fish species through advancing female reproduction by at least a year. However, there was no evidence that river origin affected sensitivity to estrogens in either sex. Thus, we conclude that chronic exposure to low level EE2 has reproductive health outcomes for both male and female roach, but we find no evidence that the nature or magnitude of the response is affected by the population origin.

Artificial reproduction of Caspian roach, Rutilus caspicus following stimulating ovulation with Ovaprim, Ovopel, and their combinations under controlled conditions

The aim of this study was to evaluate the efficiency of different hormonal agents and their combinations for spawning induction of females Caspian roach, Rutilus caspicus. Five groups of fish were injected intraperitoneally as follows: two injections of Ovaprim (T1), two injections of Ovopel (T2), a priming dose of Ovopel with a resolving dose of Ovaprim (T3), a priming dose of Ovaprim with a resolving dose of Ovopel (T4), and two injections of sterile 0.9% NaCl solution as a control group. The results showed that no fish ovulated in the control group. In hormone-treated groups, no differences were observed in ovulation success (P > 0.05). The shortest latency time and highest working and relative fecundities were observed in fish stimulated with two injections of Ovaprim (T1 group). The mean values of fertilization success in treated fish were in the range of 87.9–93.1% and the highest values were observed in T3 and T1 groups (P < 0.05). The best results in terms of ovulation index (92.1%), hatching rate (93.7%), and survival up to the eyed egg stage (89.4%) were achieved after administering two injections of Ovaprim (T1 group). There were no significant differences in the incubation time and embryos survival rates up to absorbing the yolk sac among different groups (P > 0.05). Overall, the best results of controlled reproduction of Caspian roach were obtained after using two injections of Ovaprim. Consequently, the Ovaprim is more suitable for restocking and aquaculture purposes of endangered populations of Caspian roach.

Многолетняя динамика состояния запаса тарани по результатам моделирования CMSY с ограниченными данными (1999 – 2019) в Азовском море (воды России)

Stock assessment of Azov sea roach Rutilus rutilus (Linnaeus, 1758) has been performed by CMSY model in period 1999-2019 by data-limited modelling in R. The current population status – in biological safe zone for stock biomass and no overfishing signals (B2019/BMSY = 1,32, F2019/FMSY = 0,53). Perhaps, current paper results can be a slightly incomplete in background that there is no relevant data about IUU fishery ever exists, which can lead to fishing mortality underestimation. Azov sea roach population continue to be in “depleted” status after river flow regulation in 1950’s. Joined continuous biomass estimates time series over whole fishing his-tory 1932–2019 showed at least 2 population collapses: in 1940’s and 1980’s years. According to model re-sults TAC (total allowed catch) should be accepted at level 516.9 t. If the recommendation is followed stock biomass will stay at safety in level 1828.1 t. Data limited modelling shows a good performance for sea roach in background of data lucking and in this reason still the best choose against cohor or surplus production models.

Investigation into Adaptation in Genes Associated with Response to Estrogenic Pollution in Populations of Roach (Rutilus rutilus) Living in English Rivers.

Exposure of male fish to estrogenic substances from wastewater treatment works (WwTWs) results in feminization and reduced reproductive fitness. Nevertheless, self-sustaining populations of roach (Rutilus rutilus) inhabit river stretches polluted with estrogenic WwTW effluents. In this study, we examine whether such roach populations have evolved adaptations to tolerate estrogenic pollution by comparing frequency differences in single-nucleotide polymorphisms (SNPs) between populations sampled from rivers receiving either high- or low-level WwTW discharges. SNPs within 36 "candidate" genes, selected for their involvement in estrogenic responses, and 120 SNPs in reference genes were genotyped in 465 roaches. There was no evidence for selection in highly estrogen-dependent candidate genes, including those for the estrogen receptors, aromatases, and vitellogenins. The androgen receptor (ar) and cytochrome P450 1A genes were associated with large shifts in allele frequencies between catchments and in individual populations, but there is no clear link to estrogen pollution. Selection at ar in the effluent-dominated River Lee may have resulted from historical contamination with endocrine-disrupting pesticides. Critically, although our results suggest population-specific selection including at genes related to endocrine disruption, there was no strong evidence that the selection resulted from exposure to estrogen pollution.

A newly developed genetic sex marker and its application to understanding chemically induced feminisation in roach (Rutilus rutilus).

Oestrogenic wastewater treatment works (WwTW) effluents discharged into UK rivers have been shown to affect sexual development, including inducing intersex, in wild roach (Rutilus rutilus). This can result in a reduced breeding capability with potential population level impacts. In the absence of a sex probe for roach it has not been possible to confirm whether intersex fish in the wild arise from genetic males or females, or whether sex reversal occurs in the wild, as this condition can be induced experimentally in controlled exposures to WwTW effluents and a steroidal oestrogen. Using restriction site-associated DNA sequencing (RAD-seq), we identified a candidate for a genetic sex marker and validated this marker as a sex probe through PCR analyses of samples from wild roach populations from nonpolluted rivers. We also applied the sex marker to samples from roach exposed experimentally to oestrogen and oestrogenic effluents to confirm suspected phenotypic sex reversal from males to females in some treatments, and also that sex-reversed males are able to breed as females. We then show, unequivocally, that intersex in wild roach populations results from feminisation of males, but find no strong evidence for complete sex reversal in wild roach at river sites contaminated with oestrogens. The discovered marker has utility for studies in roach on chemical effects, wild stock assessments, and reducing the number of fish used where only one sex is required for experimentation. Furthermore, we show that the marker can be applied nondestructively using a fin clip or skin swab, with animal welfare benefits.

Особенности биологии и промысла плотвы (Rutilus rutilus L.) в некоторых водоемах Республики Карелия

The article summarizes the results of long-term observations of the status of roach stocks in the main fishing waters of the Republic of Karelia (Lake Onega, Lake Ladoga, Vodlozerо and Topo-Pyaozerо reservoirs, Lake Syamozero). New data on its biology (distribution, linear and weight indicators, abundance, biomass) have been presented. There has been shown the dynamics of roach catch for a long-term period (1950–2017). It has been found that the fishing capacity of the represented roach populations corresponds to the production capabilities of its mature part and to the value obtained by biomass growth. The results of observations showed that in the studied water bodies the number and stocks of roach allow for greater volumes of catch than it is currently available and the total catch can be increased up to the calculated values of the allowable catch subject to rational fishing in the water bodies. Roach should be commercially caught at the age of 4+ years old. Given the interspecific contradictions of roach and bream, intensive fishing is recommended during the period of spawning in the straits, bays and mouths of rivers. For catching roach, it is necessary to use coastal-type fishing gear (trap nets, seines). The intensity of fishing and the increase in catches in reservoirs should be considered as mandatory measures in terms of biological reclamation in water bodies. When allocating catch quotas, the priority should be given to the most productive roach suppliers. The accompanying factor for the wide distribution of roach, along with other spring-spawning carp species (blue bream, bream), in our opinion, is warming of the climate in the region. In this regard, it is necessary to take measures to force catching the above fish species.

Ichthyo-parasitological Characteristic of Lake Vokhtozero Roach

The article presents the results of ichthyo-parasitological studies of roach Lake Vokhtozero in the area of economic activity of the cage farm OOO Raduzhnaya forel (rainbow trout). It is shown that the age structure of the roach population is represented by fish aged 3+ to 10+ years. It is based on sexually mature individuals of middle age: 4+ (25%), 5+ (31%) and 6+ (21%). Of these, 61% are females and 39% are males. Roach is infected with parasites of 14 species belonging to five systematic groups: Myxosporea - 5 species, Trematoda - 5, Ciliophora - 2, Nematoda - 1 and Monogenea - 1. The most common ones are mixosporidia and trematodes. The parasitofauna of roach corresponds to a wide spectrum of nutrition of this species with a predominance of benthic herbivorous type in older individuals.

Биология рыб озера Фролиха (Северный Байкал, Восточная Сибирь)

The fish fauna of Lake Frolikha comprises 12 species confirmed by our recent studies: roach Rutilus rutilus (L.), minnow Phoxinus phonixus (L.), stone loach Barbatula toni (Dyb.), spine loach Cobitis melanoleuca Nichols, pike Esox lucius L. lenok Brachymystax lenok (Pallas), Arctic charr Salvelinus alpinus (L.), Baikal black grayling Thymallus baicalensis (Dyb.), burbot Lota lota (L.), sand sculpin Leocottus kesslerii (Dyb.), stone sculpin Paracottus knerii (Dyb.) and perch Perca fluviatilis L. Biological peculiarities of these fishes are determined by unique geographical position and limnic characteristics of Lake Frolikha. Being a typical glacial lake it is located at rather low altitude a.s.l. and is adjacent to the unparalleled ecosystem of Lake Baikal. An underdeveloped shallow coastal zone with sparse aquatic vegetation, which is characteristic of glacial lakes, determines some biological traits of Lake Frolikha cyprinids. As compared with other mountain lakes of Baikal Rift Zone (BRZ), roach and minnow have lower rates of linear and weight growth as well as unusual population sex ratios. Male to female ratio in roach is 2:1 and in minnow it is 1:1 whereas in other lakes it reaches 1:4 and 1:10 respectively. The presence of native Baikal species in Lake Frolikha provided abundant food for piscivores: sand sculpins are the dominant food item of lenok, Arctic charr and perch. Lenok and perch demonstrate prominent linear and weight growth rate in the lake. In other lakes of BRZ with less abundant prey fish species Arctic charr typically diverge into several trophic forms, but in Lake Frolikha they established a monomorphic mostly piscivorous population. Charr from Lake Frolikha are relatively small and short-lived representatives of the large form of Transbaikalian charr. Their unique feature is river spawning, which is not observed in any other charr population within BRZ. Due to special protection regime of the territory, which minimizes catch losses, several fish species maintain natural unaffected structure of their populations evidenced by the abundance of old fish. The population of lenok is represented by 19 age groups, the population of roach – by 15 groups and that of burbot – by 12 groups. Alternatively, populations of small-sized prey species such as minnow and sand sculpin, which are heavily influenced by numerous predators include fewer age groups than in other mountain lakes of BRZ.

Morphological and biological characteristic as an indicator of population of the Siberian roach ( Rutilus rutilus lacustris) from the Chulym river in the conditions of food competition with invasive species

Biological invasions are the second most significant threat to biodiversity and native ecosystems, after direct destruction of habitats. Due to the mutual action of natural (climate change) and anthropogenic (the introduction of an alien species) factors, bleak was dispersed from the Novosibirsk reservoir to the nearest reservoirs. After sometime of the settlement of Bleak (Alburnus alburnus) along lower reaches of the Chulym river quality of the Siberian Roach (Rutilus rutilus lacustris) population in the zone of thermal pollution began to deteriorate. The analysis of the obtained data showed that the populations of roach living in the zone where the phenomenon of food competition is present and without it have significant differences in a number of morphological and biochemical indicators. Il could be due to the presence of a competitive invasive species bleak, which lives below dam of the Nazarovskaya SDPS. Thus, in the diet of a population where bleak is absent, manyinsects remains were found, while in the diet of the roach population, plant remains predominate, due to its competition with bleak for animal feed.

Temporal stability of genetic diversity revealed by microsatellite markers in restocked populations of Caspian roach, Rutilus caspicus (Yakovlev, 1870)

Abstract Rutilus caspicus is considered one of the most important bony fish with high economic value in the Caspian Sea. Since the population size of Caspian roach has decreased during recent decades, restocking of the populations is done through releasing hatchery-produced larvae into the wild. In the present study, the genetic diversity of wild and hatchery populations of R. caspicus was investigated using ten microsatellite loci. Also, microsatellite analysis was performed to compare the population structure of Caspian roach over a time frame of about 11 years. Although the allelic and gene diversity of hatchery populations tended to be lower than those of the wild populations, no significant differences in genetic diversity parameters were observed among the wild and hatchery populations. Similar variation levels were noticed among temporal samples of the same population, suggesting temporal stability in the genetic diversity of the wild populations. In most cases, significant departure from the Hardy-Weinberg equilibrium was observed after sequential Bonferroni correction. Results from analysis showed that a captive hatchery population was the most differentiated group. Also, the UPGMA dendrogram showed that the captive population was the most distant group. The stability of genetic composition between the two periods was noticed by the low and non-significant and estimates. The results from this study are anticipated to provide important information for setting up more efficient strategies for the conservation and restocking of R. caspicus.

К ВОПРОСУ РЕГУЛИРОВАНИЯ РЕЖИМА РЫБОЛОВСТВА В ВОЛГО-КАСПИЙСКОМ БАССЕЙНЕ (АСТРАХАНСКАЯ ОБЛАСТЬ), НА ПРИМЕРЕ СЕВЕРОКАСПИЙСКОЙ ВОБЛЫ

The article shows the assessment of fishing conditions of roach catches (the number of fishing grounds, fishing gears, catches, catches per unit of fishing effort, fishing intensity, etc.) at the main fishery objects of the Volga delta. There has been made the analysis of structure of size and gender composition of roach from commercial and amateur catches. The results have shown a depression of the population with negative dynamics in future. There have been determined main negative factors affecting the state of roach stock: unfavorable hydrological regime, incoordination in terms of commercial and amateur catches, limits of catch and size. In such circumstances the major purpose is to create a fishing regime, when maximum pass of fish spawners to spawning grounds is provided. The article proposes organizing a special regime of fishing roach with the aim to introduce additional limitations to the commercial fish catch, the main point of which is a transition from fine-meshed seines to medium-meshed seines in the day, when the water level in the Astrakhan region achieves an index mark as 350 cm. This measure will allow assuring a maximum pass of roach spawners to spawning grounds. A similar interdiction must be valid for amateur fishing. It should be noted that this interdiction is a provisional measure allowing to preserve and reproduce roach population.

Influence of Ligula intestinalis plerocercoids (Cestoda: Diphyllobothriidea) on the occurrence of eyeflukes in roach (Rutilus rutilus) from a lake in south-east England.

Vertebrate hosts commonly harbour concurrent infections of different helminth species which may interact with each other in a synergistic, antagonistic or negligible manner. Direct interactions between helminths that share a common site in the host have been regularly reported, but indirect interactions between species that occur in different sites are rarely described, especially in fish hosts. Plerocercoids of Ligula intestinalis are common infections of the peritoneal (body) cavity of roach (Rutilus rutilus) in freshwater habitats. These larval cestodes can cause extensive systemic pathologies to the fish host, which in turn may alter its susceptibility as a target host for other helminth species. The present study, using an existing dataset, investigates the influence of L. intestinalis (ligulosis) on frequently occurring eyefluke infections in roach sampled from a lake in south-east England. The occurrence of two species of eyefluke (Diplostomum sp. and Tylodelphys sp.) in the roach population demonstrated no significant levels of interaction with each other. The prevalence but not mean intensity or abundance of Diplostomum sp. was significantly increased in ligulosed roach, while the incidence of Tylodelphys sp. remained unchanged. Analyses of bilateral asymmetry in the occurrence of eyeflukes in left and right eyes of infected fish demonstrate that Tylodelphys sp. shows significant asymmetry in non-ligulosed roach, which is not replicated in ligulosed individuals. In contrast, Diplostomum sp. shows no evidence of asymmetry in either ligulosed or non-ligulosed fish.

Изменчивость счётных признаков сейсмосенсорной системы головы у разных видов пресноводных рыб и её связь с гидрохимическими факторами

Изучались счётные морфологические признаки у трёх массовых видов рыб ― плотвы, речного окуня и золотого карася, обитающих в небольших искусственных водоёмах центрально-восточной части Удмуртии. У отловленных рыб произведён подсчёт числа отверстий сейсмосенсорных каналов в некоторых парных покровных костях скелета головы и вычислена сумма значений этих счётных признаков (ΣSS) с усреднением для левой и правой сторон. В исследованных водоёмах измерялась также общая минерализация воды и оценивалось содержание в воде ионов кальция и магния. Для изученных видов рыб выявлен общий тренд внутривидовой изменчивости: с увеличением концентрации Mg2+ в пресной воде уменьшалось среднее значение ΣSS в исследованных популяциях. Для популяций плотвы, окуня и карася, обитающих в водоёмах с наибольшими отличиями в содержании магния, отмечены статистически значимые различия средних величин и частотных распределений дискретных вариантов этого признака сейсмосенсорной системы. В дополнение к натурным исследованиям проведены лабораторные эксперименты по аквариумному выращиванию мальков окуня и плотвы в различных гидрохимических условиях. Сформированные в воде с повышенным содержанием Mg2+ мальки окуня и плотвы характеризовались меньшим числом отверстий в окостеневших сейсмосенсорных каналах головы по сравнению с таковым контроля, а также взрослых особей из материнских популяций. Повышенные концентрации Na+ не оказали подобного влияния на формирование изученных признаков. Для объяснения наблюдённых онтогенетических эффектов рассматривается возможность прямого влияния ионов магния на скорость развития личинок пресноводных рыб, а также косвенного влияния на их морфогенез конкурентных биохимических отношений этого элемента с кальцием.

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.

Spatial distribution, total length frequencies and otolith morphometry as tools to analyse the effects of a flash flood on populations of roach (Rutilus rutilus)

AbstractFloods are known to be the major source of natural variability and disturbance in stream ecosystems. However, the management and channelisation of large rivers have impacted the fluvial geomorphology and disconnected the main channel and floodplains used as nurseries by many species of fish. This study examines the influence of a first autumnal flood event of the Ardèche River on the roach population, Rutilus rutilus (Linnaeus, 1758), in the Caderousse reach on the Rhône River. This influence was evaluated through an analysis of the spatial distribution for the abundance and size of juvenile roach and an analysis of otolith shape. Juvenile roach from the three sections of the reach formed well‐defined local populations before and after the flood event. Juvenile roach were always more abundant in the less modified section (BPS) of the river than in the other sections (RES and TAIL). While the original primary river channel was directly impacted by the flash flood, no significant difference in otolith shape was observed before or after the flash flood. Our results suggest that this part of the reach provides refuge habitats used by fish during high flow events.

Does exposure to domestic wastewater effluent (including steroid estrogens) harm fish populations in the UK?

Historic fisheries data collected from locations across the UK over several years were compared with predicted estrogen exposure derived from the resident human population. This estrogen exposure could be viewed as a proxy for general sewage (wastewater) exposure. With the assistance of the Environment Agency in the UK, fisheries abundance data for Rutilis rutilis (roach), Alburnus alburnus (bleak), Leuciscus leuciscus (dace) and Perca fluviatilis (perch) from 38 separate sites collected over 7 to 17year periods were retrieved. From these data the average density (fish/m2/year) were compared against average and peak predicted estrogen (wastewater) exposure for these sites. Estrogen concentrations were predicted using the LF2000-WQX model. No correlation between estrogen/wastewater exposure and fish density could be found for any of the species. Year on year temporal changes in roach population abundance at 3 sites on the middle River Thames and 4 sites on the Great Ouse were compared against estrogen exposure over the preceding year. In this case the estrogen prediction was calculated based on the upstream human population providing the estrogen load and the daily flow value allowing concentration to be estimated over time. At none of the sites on these rivers were temporal declines in abundance associated with preceding estrogen (effluent) exposure. The results indicate that, over the past decade, wastewater and estrogen exposure has not led to a catastrophic decline in these four species of cyprinid fish.

RETRACTED: Effects of nanometer-sized silver materials on survival response of Caspian roach (Rutilus rutilus caspicus)

The aim of this study was to investigate the acute effects of nanosilver as potentially dangerous additives to assess the mortality effects of this nanotechnology product on one of the valuable and important species of Caspian Sea. We comparedthetoxicity ofdifferent sizedsilver nanoparticles(AgNPs)whicharebeingwidelyusedwith Iranian consumersduetoitsuniqueantimicrobialactivity.EcotoxicassessmentsofAgNPsfrom twoIraniancompaniesof nanotechnology (Nanocid1: average particle size of 18 nm and Nanosil1: average particle size of < 100 nm) and silver salt (AgSO4) were conducted on the Caspian roach (Rutilus rutilus caspicus). Fish were exposed to technical dosesofNanocid (0,0.01,0.1, 0.5,1, 2.5 and 5 ppm),nominal doses ofNanosil(0,0.2, 2,20, 50, 100and 200ppm) and technical doses of silver sulfate (0, 0.001, 0.01, 0.1, 0.5, 1 and 2 ppm). The median lethal concentration (LC50) wasdeterminedwithprobiteanalysis.Theestimated96-hLC50values(95%confidencelimits)forNanocid,Nanosil andsilversaltwere0.028(0.017-0.046), 41.799(32.314-52.139)and0.003(0.001-0.006)ppm,respectively.LC50 ofsilverinsilversaltwaslowerthanotherproducts.Thepresentstudydemonstratesthatnano-Agwasseentobe less toxic than dissolved Ag þ toCaspianroach.Basedontheresultsofthisstudy,itissuggestedthatindustrial and commercial applications of AgNPs should be more carefully and thoroughly assessed as to their potential toxic effects to the aquatic environment and Caspian roach populations.