273 research outputs found
The response of eel, lamprey and brown trout to conditions associated with barriers to up- and downstream movement under experimental conditions in a flume
No full textAnthropogenic use of waterways is reducing connectivity at a rate faster than any time in geological history, sometimes causing serious declines in fish populations. Free passage of fish throughout the watercourse is necessary for species utilising different habitats for e.g. residing, spawning and feeding. Fish passes are employed to mitigate for impoundments, but are historically biased in design towards upstream migrating salmonids. Driven partly by more holistic environmental legislation, there is now an increasing interest in other species and life-stages, requiring development of fish passage criteria for multiple species during up- and down-stream migrations. To address these knowledge gaps this research programme undertook laboratory experiments with upstream migrant river lamprey, Lampetra fluviatilis, and downstream migrating European eel, Anguilla anguilla, and brown trout, Salmo trutta. The use of a large open-channel flume allowed control of the motivational state of, and stimuli encountered by the fish. The fish responses to a variety of model weirs and screens placed in the flume were assessed, allowing attainment of species and life-stage specific swimming capability and behavioural information. This research demonstrated that using large flumes where volitional swimming allows natural compensatory behaviours to be undertaken, provides more realistic swimming capability information for fish pass criteria than some traditional methods (i.e. confined swim chambers). Dependent on species and direction of movement, all structures tested had some level of impediment to migration, with small gauging weirs almost completely impeding movement of upstream migrant river lamprey under the conditions presented. Downstream migrant anguilliforms were seen to demonstrate structure oriented, thigmotactic behaviour compared to salmonids which responded to flow fields. Under high velocities, this lack of reaction to hydraulic cues may result in a higher probability of damage and mortality at facilities traditionally designed to protect salmonids. The information provided by this research, e.g. accurate swimming speeds and fish response to associated hydraulic conditions, will aid the production of effective multi-species fish pass facilitie
Advancing provision of multi-species fish passage: behaviour of adult European eel (Anguilla anguilla) and brown trout (Salmo trutta) in response to accelerating flow
No full textThe behavioural response of downstream moving European eel (Anguilla anguilla) and brown trout (Salmo trutta) to velocity gradients created by orifice weirs placed in a flume were studied. The aim was to identify interspecific variation and test two hypotheses: (1) a more abrupt velocity gradient would induce a higher avoidance response and over a greater distance, and (2) fish would acclimate to the velocity gradient by incrementally sampling conditions closer to the orifice until successful passage occurred. European eel moved along the channel floor and walls, responding after physical contact with the weir. Brown trout moved downstream head first and switched orientation at the velocity gradient without contacting the structure. Brown trout spent longer than European eel immediately upstream of a channel floor orifice, although time to pass was similar; but less time at a mid-column orifice despite taking longer to pass. The mid-column orifice delayed both species longer. European eel passed orifices head first on initial encounter with no rejections, whereas brown trout passed tail first. Positions where brown trout first switched orientation and closest point to the orifice reached during initial approach occurred closer to a channel floor than mid-column treatment. Brown trout did not appear to acclimate to the velocity gradient by sampling successively closer to the orifice. Interspecific variation in behaviour remains a key challenge in developing multi-species fish passe
Considerations of multiple species fish passage associated with the development of small-scale hydropower
No full textRecommendations for a "coarse-resolution rapid-assessment" methodology to assess barriers to fish migration, and associated prioritization tools
No full textNew Models for Data Envelopment Analysis. Measuring Efficiency Outwith the VRS Frontier
No full textSome models are presented in this paper which extend the concept of measuring superefficiency to the useful case of variable returns-to-scales (VRS), thus enabling the ranking of efficient as well as inefficient units. Two models, namely the Universal Radial Model and the Universal Additive Model, are presented that also have strong invariance properties (units and translation invariance). For both of these models a method for normalising the efficiency scores on a (0-1+) scale is presented. These models have been implemented in a software package and applied to the ranking of units in an industrial context.Data envelopment analysis (DEA), Superefficiency, Universal models
Cryptosporidiosis decline after regulation, England and Wales, 1989-2005
No full textSince new drinking water regulations were implemented in England and Wales in 2000, cryptosporidiosis has been significantly reduced in the first half of the year but not in the second. We estimate an annual reduction in disease of 905 reported cases and ≈6,700 total cases
The influence of discharge and temperature on the ability of upstream migrant adult river lamprey (Lampetra fluviatilis) to pass experimental overshot and undershot weirs
No full textThe efficiencies of fish passes specifically designed and constructed to facilitate the movement of a limited number of species and life-stages past structural barriers are likely to decline as site-specific conditions shift with a changing climate. There is a need to develop realistic fish passage criteria based on understanding swimming capability and behaviour of multiple species in relation to temperature and flow. The influence of temperature and discharge on behaviour and ability of groups of migrating adult river lamprey (Lampetra fluviatilis), a threatened species, to pass a small overshot or undershot weir at night was investigated using a large experimental flume. Lamprey approached the weirs less, and more often maintained station by using the oral disk to attach to structure, under high flows. Oral disk attachment was more commonly observed during tests employing the undershot weir. Upstream movement tended to be in close proximity to the channel walls and floor where, compared to the mid-channel, velocities were generally lower and velocity vectors more likely to be in a direction other than the bulk flow. Upstream movement was positively related to temperature, and was higher for the overshot weir. Weir passage rate was higher for undershot than overshot weirs, and negatively related to the maximum velocity at the weir. Passage rate was low when maximum velocities at the weir exceeded 1.5?m?s?1, although some fish passed at c. 1.7?m?s?1. Passage efficiency, the number of weir passes as a percentage of the number of approaches, was also higher for the undershot weir, but was not affected by discharge because lamprey approached less frequently at high flows. This study provides fish passage criteria under realistic conditions for an infrequently studied anguilliform species of conservation concern and provides a methodological perspective by which to improve fishway suitability for a wider range of species subject to changing climate
Free radicals formed by H(Mu) addition to fluoranthene
No full textMuonium has been used as an H atom analogue to investigate the free radicals formed by H addition to the polyaromatic hydrocarbon fluoranthene. There are nine unique carbons in the molecule, but only five radicals were detected. Muon and proton hyperfine constants were determined by transverse field µSR and µLCR, respectively, and compared with calculated values. All signals were assigned to radicals formed by Mu addition to C-H sites. There isno evidence for addition to the tertiary carbons at ring junctions.Peer reviewedFinal article publishe
Enolization of acetone in superheated water detected via radical formation
No full textPeer reviewedMuoniated free radicals have been detected in muon-irradiated aqueous solutions of acetone at high temperatures and pressures. At temperatures below 250 °C, the radical product is consistent with muonium addition to the keto form of acetone. However, at higher temperatures, a different radical was detected, which is attributed to muonium addition to the enol form. Muon hyperfine coupling constants have been determined for both radicals over a wide range of temperatures, significantly extending the range of conditions under which these radicals and the keto−enol equilibrium have been studied.Final article publishe
Correction for Colón-González et al., Limiting global-mean temperature increase to 1.5-2 °C could reduce the incidence and spatial spread of dengue fever in Latin America.
No full textCorrection for “Limiting global-mean temperature increase to 1.5–2 °C could reduce the incidence and spatial spread of dengue fever in Latin America,” by Felipe J. Colón-González, Ian Harris, Timothy J. Osborn, Christine Steiner São Bernardo, Carlos A. Peres, Paul R. Hunter, and Iain R. Lake, which was first published May 29, 2018; 10.1073/pnas.1718945115 (Proc. Natl. Acad. Sci. U.S.A. 115, 6243–6248). The authors note that Rachel Warren and Detlef van Vuuren should be added to the author list. Rachel Warren should appear as the seventh author, following Paul R. Hunter. Detlef van Vuuren should appear as the eighth author, following Rachel Warren and preceding Iain R. Lake. Rachel Warren should be credited with designing research. Detlef van Vuuren should be credited with contributing data. The corrected author line, affiliation line, and author contributions appear below. The online version has been corrected. The authors also note that the following statement should be added to the Acknowledgments: “R.W. and D.v.V. also received funding from the United Kingdom government, Department for Business, Energy, and Industrial Strategy, as part of the ‘Implications of Global Warming of 1.5 °C and 2.0 °C Project.’
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