Session B5: Efficiency of a Nature-Like Bypass Channel at Rodley Weir, River Aire

Abstract: Man-made physical barriers (weirs) have disrupted longitudinal connectivity in many river systems around the world for centuries. Impacts of weirs on fish communities centers on the reduced ability of fish to perform upstream migrations. To counter the potential effects these structures are having on fish communities, a number of fish pass designs have been developed to ease passage around potential barriers. To monitor the effectiveness of a recently constructed nature like bypass on the River Aire, Passive Integrated Transponder (PIT) systems were installed to observe movements of brown trout (Salmo trutta). The array consists of four swim through antennas, two at either end of the pass so that swimming direction could be determined. A total of 111 wild brown trout were caught, PIT tagged and released 380 m downstream of the fish pass entrance. In total 57 brown trout (51%) were detected on the most downstream loop, and of these 49 successfully entered the pass (86%). Thirtyeight of these successfully exited the pass in an upstream direction (78%). Further analysis found that a select number of fish used the pass as an area of refuge during high flows. The possible reasons for these findings are discussed in relation to flow, temperature, time of day, season and fish size. This information is important to improve our understanding of fish pass performance, thus informing future best practice guidance of fish passage designs

Membrane Reactor Based on Hybrid Nanomaterials for Process Intensification of Catalytic Hydrogenation Reaction: an Example of Reduction of the Environmental Footprint of Chemical Synthesis from a Batch to a Continuous Flow Chemistry Process

Membrane processes represent a well matured technology for water treatment with low environmental footprints compared to other type of processes. We have now combined this technology with nanomaterials, ionic liquids (negligible vapor pressure), and poly(ionic liquids) in order to enlarge the field of applications while benefiting from the advantages of membranes. We have modified flat sheet water filtration membrane and used it as both catalytic support and reactor with the advantages to make the reaction and the separation of products in only one step. For this purpose, catalytic metallic nanoparticles of palladium (diameter of ca. 2 nm) were synthesized in a gel-poly(ionic liquid) layer grafted at the surface of polymeric filtration membranes by UV-photografting method. The so obtained catalytic membrane was successfully applied in the hydrogenation of trans-4-phenyl-3-buten-2-one in forced flow-through configuration, which gave full conversion in a few seconds (2.6 s) showing advantages over the batch reactor process (in that case, palladium nanoparticles were synthesized in the ionic liquid [MMPIM][NTf2] (1,2-dimethyl-3-propylimidazolium bis-(trifluoromethylsulfonyl)imide)). Nevertheless, the catalytic membrane used in submerged mode no more prevailed over the batch reactor. Catalytic nanoparticles remain highly active in the membrane after 12 cycles of reaction without need of recuperation. Results were compared to one obtains with a similar system in batch reactor conditions, showing high efficiency of our process in term of selectivity and reactivity, combined to an important compactness, the productivity of the catalytic hollow fiber membrane reactor and permitting to operate at larger scale with promising results in an environmental friendly way in term of energy and product (metal, solvent) consuming

High catalytic efficiency of palladium nanoparticles immobilized in a polymer membrane containing poly(ionic liquid) in Suzuki–Miyaura cross-coupling reaction

The elaboration of a polymeric catalytic membrane containing palladium nanoparticles is presented. The membrane was prepared using a photo-grafting process with imidazolium-based ionic liquid monomers as modifying agent and microPES® as support membrane. Ionic liquid serves as a stabilizer and immobilizer for the catalytic species, i.e. palladium nanoparticles. The Suzuki–Miyaura cross-coupling reaction was carried out on the catalytic membrane in flow-through configuration. Complete conversion was achieved in 10 s through one single filtration, without formation of byproducts. The apparent reaction rate constant was three orders of magnitude greater than in a batch reactor. No catalyst leaching was detected. This membrane offers the possibility of continuous production with no need for a separation step of the catalyst from the reaction medium

Session B4: Fine-Scale 2D Acoustic Tracking of the Behaviour of Salmonids to Investigate Delays and Failures in Fish Passage; Implications for Assessing the Efficiency of Fish Passes

Abstract: Many studies of fish passage are limited to consideration of coarse scale efficiency metrics; however the level of resolution they have for explaining changes in these metrics is often limited. In many cases assessments of fish pass performance are instigated due to (and complicated by) factors such as changes in fish pass design, construction of hydropower schemes and/or associated changes in hydro-morphology. In such cases finer scale descriptions of passage behaviour and fish pass proximity behaviour may be required to identify changes in passage efficiency and elucidate the factors influencing them. This presentation describes a five year acoustic tracking study (3 years pre and 2 years post installation of a co-located hydropower scheme with Larinier fish pass) of the 2D behaviour of 138 sea trout and 18 salmon as they approached the fish pass entrance and hydropower outfall on Ruswarp Weir (River Esk, England). The study determined the fine scale (sub-metre resolution) spatial and temporal utilisation of the fish pass pool and approach behaviours; analysing these in relation to river flows, tidal conditions, operation of the hydropower scheme, a change in design of the fish pass and the associated changes in pool morphology. In particular the analysis considered the delays in fish passage and behaviours of fish that were successful or unsuccessful in using the fish pass, and the different conditions they encountered whilst approaching the fish pass. The results showed that alongside a significant increase in the proportion of failed passages (reduced fish pass efficiency from 100% to 69% for sea trout) there was a significant increase in delay of passages and changes in the behaviour of fish and spatial utilisation of the pool. Some of these changes potentially relate to operation of the hydropower whilst others may relate to changes in the pool morphology and fish pass

Session B8: Changes in Fish Passage Metrics Following the Co-Location of a Low-Head Hydropower Turbine with an Existing Fish Pass; Revealed by an Acoustic Tracking Study of Migratory Salmonids

Abstract: Co-location of hydropower turbine outfalls with fish pass entrances has been suggested as current best practice to optimise the attraction flows for the fish pass and to mitigate the perceived negative impacts of small run-of-river hydropower schemes. To test this a five year acoustic tracking study was instigated to monitor the installation of a low-head Archimedes screw turbine alongside an existing pool-traverse fish pass on Ruswarp Weir, at the tidal limit of the River Esk (England). The study tracked the behaviour of salmon and sea trout as they approached the weir and fish pass and determined the overall passage rate (% of tagged fish ascending the weir by any route), the attraction efficiency (% of tagged fish entering the pool below the fish pass) and the fish pass efficiency (% of tagged fish detected in the pool below the fish pass that ascended the weir via the pass). Over the five years (3 years pre and 2 years post) 138 sea trout and 18 salmon were tracked using acoustic tags with arrays of fixed and mobile hydrophones to determine large-scale behaviour in the tideway and in the approach to the fish pass (a pool-traverse pass, replaced by a Larinier pass during construction of the turbine). The study showed that following the co-location of the turbine and the construction of the Larinier pass there was a significant increase in the attraction efficiency (35% to 69%) and the overall passage rate (35% to 53%) but a significant reduction in fish pass efficiency (100% to 69%) for sea trout. These results support the concept of colocating outfalls to increase attraction efficiency whilst at the same time raise concerns that this also reduced the fish pass efficiency; perhaps causing a distraction and delay to migrants, with an associated increased risk of predation

Upstream passage of adult sea trout (Salmo trutta) at a low-head weir with an Archimedean screw hydropower turbine and co-located fish pass

© 2018 CSIRO. The exploitation of riverine systems for renewable energy has resulted in large numbers of small-scale hydropower schemes on low-head weirs. Although considered a clean and 'green' energy source in terms of emissions, hydropower can affect upstream migrating species by diverting flow away from viable routes over the impoundment and attract fish towards the turbine outfall. In an attempt to reduce this negative effect, hydropower outfalls with co-located fish-passage entrances are recommended, utilising turbine flows to attract fish towards the fish pass. The present study used acoustic telemetry to understand the performance of a co-located Larinier fish pass at a low-head hydropower scheme at a weir on the tidal Yorkshire Esk, England. The majority of the sea trout (anadromous Salmo trutta L) individuals that approached the impediment were attracted to the hydropower and the co-located fish pass. Fish ascended through the pass under a wide range of river flows, tide heights, downstream river levels and hydropower flows, and there was no evidence that the hydropower operation affected fish-pass ascent. The information presented is urgently required to inform management decisions on the operation of hydropower schemes during the migratory period of salmonid fish, and help determine best-practice designs and operation at these facilities

Catchment-wide interactive effects of anthropogenic structures and river levels on fish spawning migrations

Worldwide, rivers are extensively fragmented by anthropogenic structures, reducing longitudinal connectivity, inhibiting migration and leading to severe declines in many fish populations, especially for diadromous species. However, few studies have determined the effects of annual differences in hydrology on catchment penetration past barriers to spawning habitats. We investigated the upstream spawning migration of 120 (n = 61 & 59) acoustic tagged river lamprey (Lampetra fluviatilis) across two contrasting (dry and wet) years in the River Yorkshire Ouse, England. Overall, significantly more lamprey reached spawning habitat (76% vs 39%) and penetrated significantly further upstream (median [km] from release, 53.9 vs 16.8) in the wet year than the dry year. Passage at weirs was almost exclusively during elevated river levels, which directly and collectively influenced catchment-wide distribution, especially in the dry year. Indeed, higher proportions entered two upper tributaries in the wet year (9.8% vs 27.1% and 9.8% vs 30.5%), due to increased passage efficiencies at the two main river weirs (60.5–87.5% and 54.5–83.8%), and reached assumed spawning locations 66.5% and 10.9% quicker. By contrast, there was no difference in numbers of lamprey entering, or time taken to arrive at assumed spawning location, in the two lower river tributaries between years. Our study supports the landscape-scale paradigm for ecosystem restoration because of the observed catchment-level effects of hydrology and barrier distribution on fish migration. Connectivity restoration for migratory fish should be implemented at a catchment scale, with planning incorporating spatial information regarding accessibility to key habitats to reap the largest gains

The Response of River-Resident Fish to Reservoir Freshet Releases of Varying Profiles Intended to Facilitate a Spawning Migration

Natural hydrological regimes encompass varying seasonal flow characteristics that provide fish with cues and opportunities for upstream spawning migrations, but these flows are often modified/absent in regulated rivers. Compensatory artificial flows (freshets) can be released from reservoirs to replicate these characteristics, but studies testing their effectiveness are limited. To address this, river‐resident brown trout, a species known to undertake spawning migrations, were manually tracked using radio telemetry in a regulated upland river in northern England in response to 11 freshet releases of differing timing, magnitude and duration. Spawning migrations were not observed because extent of movement during freshets was generally small and the pattern of movement (i.e. directionality and relocation indices) was comparable between impact/control reaches. Movements during freshets were comparable with those observed the days immediately before/after and were small relative to the entire tracking period. In conclusion, freshets characteristic of those recommended to produce “naturalized” autumn/winter flow elevations did not stimulate/facilitate spawning migrations of river‐resident brown trout under the given seasonal conditions. Outside freshets, longer unidirectional movements occurred during low flow periods and elevated river level due to rainfall, including during periods of reservoir overtopping. Notwithstanding, fish in experimental reaches were significantly more active (total distance moved) and occupied a larger extent of river (range during freshet) than those in control reaches during short‐duration freshets. Therefore, during dry years/when (autumn/winter) reservoir overtopping events are unlikely, small‐magnitude freshets providing flows that allow fish short opportunities to search for/find superior local habitat whilst minimising total water released are recommended

Regional differences in APD restitution can initiate wavebreak and re-entry in cardiac tissue: A computational study

Background Regional differences in action potential duration (APD) restitution in the heart favour arrhythmias, but the mechanism is not well understood. Methods We simulated a 150 × 150 mm 2D sheet of cardiac ventricular tissue using a simplified computational model. We investigated wavebreak and re-entry initiated by an S1S2S3 stimulus protocol in tissue sheets with two regions, each with different APD restitution. The two regions had a different APD at short diastolic interval (DI), but similar APD at long DI. Simulations were performed twice; once with both regions having steep (slope > 1), and once with both regions having flat (slope < 1) APD restitution. Results Wavebreak and re-entry were readily initiated using the S1S2S3 protocol in tissue sheets with two regions having different APD restitution properties. Initiation occurred irrespective of whether the APD restitution slopes were steep or flat. With steep APD restitution, the range of S2S3 intervals resulting in wavebreak increased from 1 ms with S1S2 of 250 ms, to 75 ms (S1S2 180 ms). With flat APD restitution, the range of S2S3 intervals resulting in wavebreak increased from 1 ms (S1S2 250 ms), to 21 ms (S1S2 340 ms) and then 11 ms (S1S2 400 ms). Conclusion Regional differences in APD restitution are an arrhythmogenic substrate that can be concealed at normal heart rates. A premature stimulus produces regional differences in repolarisation, and a further premature stimulus can then result in wavebreak and initiate re-entry. This mechanism for initiating re-entry is independent of the steepness of the APD restitution curve