5,197 research outputs found
Endocrine disruption in juvenile roach from English rivers: A preliminary study
No full textJuvenile roach Rutilus rutilus from seven rivers of varying water quality were examined for evidence of endocrine disruption. The majority of roach from five of these rivers had femalelike reproductive ducts. The results suggest that juvenile, rather than adult, fish could be used in studies of endocrine disruption in wild fish populations
Predicting the ecological consequences of river management for a riverine cyprinid fish.
No full textCurrent river management seeks to resolve a compromise between stakeholder interests, ecosystem services provision and conservation aims, especially in relation to assessment of ecosystem health. While management decisions should be evidenced-based, current population and habitat models fail to incorporate fish behaviour and the interactions between fish and their environment, thus limiting their ability to predict management-relevant, population responses to environmental change. In order to address these weaknesses, an individual-based model is developed and parameterised to predict the distribution and growth of roach (Rutilus rutilus), a common, generalist, freshwater fish; known to be typically dominant in heavily modified rivers. Such a model seeks to build on current management models and practices, with emphasis on improving recruitment of juvenile roach. Virtual forager parameters are derived from foraging experiments, published investigations, models of roach behaviour and bioenergetics. Data collected from field studies in a typical, highly modified, lowland river are used to describe the environment and initial fish population with subsequent data on fish population trends used to validate the IBM, under a pattern-oriented modelling approach; specifically growth rate and habitat distribution patterns. River management practices including the removal of in-stream aquatic macrophytes and regulation of flow regime for flood risk management are predicted as potentially damaging to roach recruitment, subsequent year-class strength and therefore, populations in subsequent years. Recommendations for more sympathetic management schemes are provided. The modelling framework described here can be used to produce robust predictions of roach population patterns in riverine habitats and allows the user to test the impact of environmental change on cyprinid fish, enabling the modelling system to be used to develop proactive, evidence-based management in light of current rates of environmental change
Assessing the Sensitivity of Different Life Stages for Sexual Disruption in Roach (Rutilus rutilus) Exposed to Effluents from Wastewater Treatment Works
No full textSurveys of U.K. rivers have shown a high incidence of sexual disruption in populations of wild roach (Rutilus rutilus) living downstream from wastewater treatment works (WwTW), and the degree of intersex (gonads containing both male and female structural characteristics) has been correlated with the concentration of effluent in those rivers. In this study, we investigated feminized responses to two estrogenic WwTWs in roach exposed for periods during life stages of germ cell division (early life and the postspawning period). Roach were exposed as embryos from fertilization up to 300 days posthatch (dph; to include the period of gonadal sex differentiation) or as postspawning adult males, and including fish that had received previous estrogen exposure, for either 60 or 120 days when the annual event of germ cell proliferation occurs. Both effluents induced vitellogenin synthesis in both life stages studied, and the magnitude of the vitellogenic responses paralleled the effluent content of steroid estrogens. Feminization of the reproductive ducts occurred in male fish in a concentration-dependent manner when the exposure occurred during early life, but we found no effects on the reproductive ducts in adult males. Depuration studies (maintenance of fish in clean water after exposure to WwTW effluent) confirmed that the feminization of the reproductive duct was permanent. We found no evidence of ovotestis development in fish that had no previous estrogen exposure for any of the treatments. In wild adult roach that had previously received exposure to estrogen and were intersex, the degree of intersex increased during the study period, but this was not related to the immediate effluent exposure, suggesting a previously determined programming of ovotestis formation
Habitat selection and indirect interactions in fish ommunities
No full textTo increase the understanding of freshwater lake ecosystems, I have studied the habitat selection of perch (Perca fluviatilis L.), roach (Rutilus rutilus (L.)), and vendace (Coregonus albula (L.)). These fish species use the pelagic and the littoral-benthic habitats in lakes to different extents. Perch and roach are omnivorous, and perch become piscivorous at larger sizes. Vendace is a pelagic species specialized in eating zooplankton. Vendace was expected to affect biotic interactions and habitat use of roach and perch, both directly and indirectly.
I used monitoring data to examine how species distribution patterns, as well as population structures, depended on species composition. In a predation experiment, I studied the relative predation sensitivity as well as evasive behaviours of roach and vendace, with piscivorous perch used as predators. In foraging experiments in aquaria, I studied foraging efficiencies and swimming performances of roach and vendace eating zooplankton in different temperature and light treatments. I then applied metabolic models for roach and vendace, respectively, to compare their net energy gain in different abiotic conditions.
Roach used the pelagic habitat less, and the biomass of roach was lower in lakes with vendace. Results did not support the prediction that perch populations would benefit from the presence of vendace. However, results indicated that a release of competition for small perch may be mediated by vendace, through changed habitat use of roach, increasing the possibilities for predation. Roach and vendace were similar in their sensitivity to predation, indicating that energy gain can explain their habitat use. Foraging efficiencies did not explain the habitat use of roach and vendace in the field. However, the net energy gain in different abiotic conditions, could explain observed patterns of their habitat use in lakes.
This thesis shows how the trade-off between mortality and net energy gain is manifested in habitat use. Including habitat selection in ecological studies may increase our understanding of biotic interactions. Metabolic costs as well as foraging abilities in different abiotic conditions are important for explaining the habitat use of species. Such knowledge can make it possible to forecast how interacting fish species may be affected by environmental change
Factors affecting the growth and recruitment of cyprinid populations of the River Wensum, Eastern England, with specific reference to roach Rutilus rutilus (L.).
No full text1. The roach Rutilus rutilus population of the River Wensum, Eastern England, has long been the topic of deliberation amongst the angling community due to a perceived decline in their catches since the 1970s. Analysis of fish population survey data collected by the Environment Agency and its predecessor organisations since 1983 revealed that although the roach populations have shown considerable temporal variability around their long-term mean abundances, their estimated abundance in 2009 was not significantly different to that estimated in the 1980s. A significant decline in the abundance of dace Leusicus leusicus (L.) was detected, although the abundance of chub Leuciscus cephalus (L.) has increased. 2. Annual variation in the recruitment strength of 0 group roach contributed to their temporal variability in population abundance. Recruitment was largely driven by climate, specifically water temperatures in the first year of life of year classes. Point abundance electric fishing sampling conducted in 2007 and 2008 revealed that nursery habitat was limited for the larval and juvenile life stages of the roach population, revealed by only 6 % of all points sampled containing 4 at least one roach. The probability of roach capture in a sample point only exceeded 0.80 when depths exceeded 1m and macrophyte cover the sampled area exceeded 60 %. 3. The growth rate of adult roach has declined between the 1970s and the present, with this long-term depressed growth only apparent since the initiation of phosphate stripping in the mid to late 1990s. Prior to phosphate stripping, roach growth was largely dependent on water temperature; post-stripping, it was significantly associated with levels of ortho-phosphate. Thus, whilst this reduction in nutrient input into the river was positive for its chemical and biological water quality, it now prevents individual fish growing rapid to a size considered as a 1Especimen 1F by anglers (>1 kg). It is this depressed growth and reduction in the numbers of 1Especimen 1F roach being produced in the river that is contributing to the perceived declines of roach by the angling fraternity. 4. To prevent flooding in the river catchment, a number of flood prevention works have been regularly completed by authorities, including channel straightening and removal of in-stream woody debris. Whilst these tend to have negative consequences for fish production, the cutting of in-stream macrophytes during the summer months to ensure the channel was sufficiently clear to facilitate flood relief flows was measured as having a significant deleterious impact for juvenile roach. Comparison of pre- and post-weed cutting electric fishing point samples revealed presence and abundance of juvenile roach decreased by approximately 50 % following weed cutting. 5 5. These outputs were used to develop a series of management recommendations to assist the production of roach in the river without compromising other river management perspectives such as flood risk management. A key aspect of this is the creation of in-stream and off-channel refuge and nursery areas for roach that promote their survival and growth across all aspects of their lifecycle
The disenfranchisement of prisoners : Roach v Electoral Commissioner & Anor - modernity v feudalism
No full textDavid Brown takes a road trip to Canberra for the Roach fixture at the High Court where modernity is attempting a fight-back against the resurrection of civil death. With echoes of Hunter S Thompson as rugby league follower, the author recounts a trip to Canberra to observe a case in which Vickie Lee Roach, an Indigenous woman prisoner, challenged (successfully as it later turns out) the Howard government's 2006 legislation disenfranchising all serving prisoners.\ud
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Potential directions for drug development for osteoarthritis
No full textBackground: osteoarthritis (OA) is a frustrating disease for both patient and physician because neither cause nor cure is known and there are currently no disease-modifying drugs. Objective: To review current therapeutic approaches as well as new findings regarding OA pathoetiology that could form the basis of future direction for the development of drugs to prevent or slow down disease progression. Methods: After reviewing disease progression in human OA, as demonstrated by histological analyses, the reasons for cartilage erosion are explored and possible therapeutic approaches are highlighted. Results/conclusions: OA may be an epigenetic disease. This new concept can explain many aspects of the disease and provide reasons why therapeutic approaches until now have met with little success
ROACH accelerated BLAST
No full textIncludes abstract.Includes bibliographical references (p. 115-118).Reconfigurable computing, in recent years, has been taking great strides in becoming part of mainstream computing largely due to the rapid growth in the size of FPGAs and their ability to adapt to certain complex applications efficiently. This dissertation investigates the reuse of application specific hardware developed for radio astronomy in accelerating a popular bioinformatics algorithm
Building a Sod House in western Nebraska.
No full textPhotographer's note: Home of Frank Roach, Keith County, about 1890
Portrait of Mr. Roach
No full textPortrait of Mr. Roach. He is wearing suit and tie.https://mavmatrix.uta.edu/specialcollections_wdsmithphotography/10849/thumbnail.jp
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