Opportunistic use of estuarine habitat by juvenile bull trout, <Emphasis Type="Italic">Salvelinus confluentus</Emphasis>, from the Elwha River before,during, and after dam removal

Estuaries are used by anadromous fishes, either as the definitive marine habitat or as transition habitat as they move to fully marine waters, and extent of estuary use may vary with habitat conditions and fish attributes. Bull trout (Salvelinus confluentus) are commonly fluvial or adfluvial, though anadromous populations also exist. However, little is known about estuary use, especially by juveniles of this threatened species. We sampled the estuaries of the Elwha River, where a spawning population exists, and the nearby Salt Creek, where none exists, to reveal seasonal timing of estuarine use by juvenile bull trout, size of those using the estuary, and possible use of the non-natal estuary. We captured juvenile bull trout (all ≥100 mm FL, most <300 mm) in the Elwha River estuary in all months except August, but primarily December through May. None was captured in Salt Creek’s estuary despite comparable sampling effort. We also evaluated how dam removal on the Elwha River influenced bull trout estuarine occupancy by sampling before, during, and after dam removal, because this process enlarged the estuary but also increased turbidity and sediment transport in the lower river. Catches were low before dam removal, increased during and immediately after removal, and returned to low levels in recent years, suggesting that juveniles temporarily sought refuge from conditions associated with dam removal. Our findings indicate juvenile bull trout occupy estuarine habitat opportunistically; this information may aid conservation efforts as anadromous populations occur elsewhere in rivers with estuaries altered by human development.     

Spawning migration behaviour of sea trout (Salmo trutta L.) in a boreal river system: effects of flow conditions and obstacles on migratory activity

In this study, radio telemetry was used to examine the upstream spawning migration behaviour of anadromous brown trout (sea trout), Salmo trutta L., in a boreal river system, the River Isojoki, western Finland. The aim was to study the movement activity and migration characteristics of trout during the upstream spawning migration, as well as to locate the important spawning habitats and study the spawning characteristics. Furthermore, the authors analysed how flow conditions and a hydropower dam, with adjacent fishways, affected the upstream spawning migration. Tagged trout spawned in both the main stem and four tributaries, with spawning taking place from early October to November. The movement activity of radio-tagged trout was influenced by a hydropower dam (Perus dam), with spring migrators spending prolonged periods at the dam area, postponing the migration upstream. Flow conditions affected the total time spent at the dam area, as well as the movement activity in the free-flowing sections above the dam, with increasing flow stimulating activity. In addition, time of river ascent and location of spawning area had a significant effect on the movement activity of tagged trout. These results are further evidence that synergistic effects of flow and migratory obstacles can negatively influence migrations of anadromous fish, regardless of constructed fishways. The management of flow regimes and the efficiency of fishways are vital, as climate change will likely influence the flow and increase the water temperature of boreal river systems, further aggravating issues caused by obstacles.     

Food habits of Coexisting Salmonines above and below Stronach Dam in the Pine River, Michigan

Although dam removal has become an increasingly popular tool for river restoration, there is limited knowledge regarding the ecological effects of dam removal. The purpose of our study was to document feeding habits of coexisting brook charr, brown trout, and rainbow trout above and below a dam that is in the process of a staged removal. Modification of sediment transport caused by Stronach Dam since 1912 has affected stream channel configuration, fish habitat, and many other physical and biological processes. In order to document salmonine feeding habits above and below the dam, we selected zones to represent downstream conditions and areas of river upstream of the dam that encompassed the original reservoir and a stretch of river further upstream that was not hydraulically influenced by the dam. Because physical habitat largely governs aquatic community composition in streams, we expected these effects to be reflected in the fish and macroinvertebrate communities. In particular, we expected limited prey availability and salmonine feeding in the impacted upstream and downstream zones characterized by fine substrate composition and greater macroinvertebrate diversity and salmonine feeding opportunities in the non-impacted zone characterized by coarse substrate. We also expected mean percent wet stomach content weights to be higher downstream, as other studies have documented an increase in piscivory on blocked migratory prey species downstream of dams. Contrary to expectations, the downstream zone of the river contained the highest abundance of drifting invertebrate taxa and, although differences in habitat occurred among the zones, the diversity of drifting macroinvertebrates and stomach contents of salmonines were similar throughout the river. Thus, in this case, the presence of altered habitat caused by a dam did not appear to negatively affect salmonine food habits. Consequently, we expect no major changes in salmonine food habits after the dam removal is completed.     

Bird assemblages on Amazonian river islands: Patterns of species diversity and composition

The principles of island biogeography are rarely applied to the animal assemblages of Amazonian river islands. Here, we compare bird assemblages of Amazonian river islands with a variety of mainland habitats. We also examine how bird species diversity and composition are related to island physical attributes. Birds were sampled with mist nets and qualitative censuses on 11 river islands and 24 mainland sites on the lower reaches of the Rio Negro in the Brazilian Amazon. Island bird assemblages were characterized by lower species richness and a higher abundance of a few dominant species. Additionally, the species composition of the islands was distinct from that of the mainland, including the nearby floodplain habitats. The number of bird species increased with island size and habitat diversity, and decreased with degree of isolation. In addition, small islands tended to harbor an impoverished subset of the species present on larger ones. Bird species diversity and composition on Amazonian river islands are likely influenced by the ecological succession and historical events affecting island formation. Considering their small total area across the Amazon basin, these insular fluvial communities could be disproportionately threatened by river channel disturbances related to climate change or hydroelectric dam development. Abstract in Portughese is available with online material.     

Movement of walleye in an impounded reach of the Au Sable River,Michigan, USA

Synopsis We estimated long-range spawning and foraging movements of walleye and observed their use of river and reservoir habitats between two large hydroelectric dams on the Au Sable River, Michigan. We used radiotelemetry to monitor seasonal and daily movements of 11 large walleye. Walleye ranged throughout the entire reach between the two dams. Eight of the 11 fish used both river and reservoir locations. Walleye migrated upriver in April or May and presumably spawned near the dam tailwaters. After spawning, walleye remained in the river for up to 6months, usually establishing local ranges. During this time, they occupied low-velocity refuges within the first 25 km of the upstream dam. They seldom occupied the downstream area, which has higher variation around the mean temperature. Food availability and water temperature may have affected the length of time that walleye remained in the river after spawning. All walleye overwintered in the reservoir. We designed this study to evaluate if walleye have a potential negative impact on brown trout, Salmo trutta. In summer, walleye were often present near sites where fingerling trout were stocked. We found the highest potential for interaction between the two species occurs within the first 25km of the upstream dam during summer. The movement patterns of and habitats used by large walleye validate concerns that walleye could compete with adult brown trout for food and resting sites and prey on juvenile brown trout.     

Current State of Conditions for Reproduction of the Black Sea Trout <Emphasis Type="Italic">Salmo trutta labrax</Emphasis> in the Mzymta River

Conditions of reproduction and distribution of the Black Sea trout Salmo trutta labrax in the basin of the Mzymta River after Olympic objects′ construction are considered. In the main river channel of the Mzymta, the structure of spawning and nursery grounds are destroyed along 57 km from the river mouth. The total area of these grounds in the Mzymta basin is 572800 m², and 49% of this area is situated above the dam of the Krasnopolyanskaya Power Plant and is inaccessible for spawners of the migratory form of the Black Sea trout listed in the Red Data Book of the Russian Federation. Consequently, natural reproduction of the migratory form discontinued. The resident form of trout still exists in the upper parts of the Mzymta and in 19 of its tributaries not affected by construction. On the 2.4-km-long stretch of the riverbed situated below the inflow of the Pslukh tributary, the substrate is in the process of natural restoration due to the descent of mudslides followed by washing of the substrate by the flow. The river is partially inhabited by trout individuals from habitats not affected by construction.     

Effects of altered river network connectivity on the distribution of Salmo trutta: Insights from a metapopulation model

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Temporal variability in the impact of river regulation on thermal regime and some biological implications

• 1 Ten years of hourly water temperature data for three river sites in south-west England were used to investigate the longer-term thermal effects of river regulation. The impact of reservoir impoundment on downstream invertebrate and trout development were simulated using daily mean temperature data in conjunction with published biological models.
• 2 The main effects of regulation on water temperature were to increase the mean value, eliminate freezing conditions, depress summer maxima, delay the annual cycle and reduce diel fluctuation. These impacts persisted over a distance of at least 5km below the dam but declined downstream, especially for seasonal and diurnal variations.
• 3 Simulations suggested that regulation is likely to have had a greater impact on the development of brown trout (Salmo trutta) than on the development of one Ephemeroptera and four Plecoptera species. Trout fry were predicted to emerge up to 57 days earlier, and to weigh up to 67% more by the end of the year following swim-up, in the regulated compared with the unregulated river.
• 4 Marked inter-annual contrasts in the physical and biological consequences of impoundment were evident, indicating that long-term studies are required to define properly the effects of river regulation.

     

A proposed process for applying a structured decision‐making framework to restoration planning in the Atchafalaya River Basin,Louisiana, U.S.A.

Environmental decision‐making issues in the Atchafalaya River Basin (ARB), Louisiana require innovative approaches that combine scientific understanding and local stakeholder values. Management of the ARB has evolved from strong federal control to establish the ARB as a primary floodway of the Mississippi River and Tributaries Project to a state and federal collaboration to accommodate fish and wildlife resource promotion, recreational opportunities, and economic development. The management policy has expanded to include a growing number of stakeholders, but the decision‐making process has not kept pace. Current conflicts among many local stakeholder groups, due in part to their lack of involvement in the decision‐making process, impede restoration efforts. The absence of a long‐term collective vision for the ARB by both local stakeholder groups and management agencies further confounds these efforts. This paper proposes a process to apply a structured decision‐making framework, a values‐based approach that explicitly defines objectives, to promote stakeholder‐driven restoration efforts in the ARB and to better prepare for and manage long‐term environmental issues. The goals of this approach are: (1) to create a process founded on stakeholder values and supported by rigorous scientific assessment to meet management agency mandates and (2) to establish a transparent process for restoration planning in the ARB that incorporates current and future non‐governmental stakeholders into the decision‐making process. Similar frameworks have been successful in other river basins; we feel the structure of current restoration efforts in the ARB is well‐suited to adopt a values‐focused management framework.     

A method for prioritizing the reestablishment of river continuity in Austrian rivers

River continuity is one of the hydro-morphological elements supporting the classification of the ecological status of rivers. In order to achieve good ecological status in the continuity of rivers, the impacts of anthropogenic activities must be limited to the extent that some fish age classes may be missing and there may only be slight changes in species composition and abundance from the type specific community. The main goal of the project is to list priorities for removing obstruction to migration within 12 years to reestablish river continuity so as to allow undisturbed migration of aquatic organisms. The ecological status of the river, the cost–benefit ratio of the proposed restoration and the distance between obstructions are analysed. More than 200 obstructions in about 170 km of river were evaluated. A 1st ranking of the parameter “extension of undisturbed river length” shows significant alterations in comparison with the 2nd and 3rd ranking, where the river length is weighted over the parameters “ecological status” of the river reach and the “cost–benefit ratio” of the measure. The ecological status is classified by comparing the present versus the potential natural morphological conditions (Leitbild). The cost–benefit ratio takes into account the increase of the fish species composition and the cost of the measures in relation to local circumstances of available property and height of the drop. Examples of obstructions in the Pinka R. move back in the priority list to a maximum of −9 places and forwards to a maximum of +8 places. As a result the list of obstructions by priority for removal to be removed first at the top is analysed. The financial policy and a schedule for removal for the period 2003–2015 are based upon the results of the priority list. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: R. L. Welcomme & G. Marmulla Hydropower, Flood Control and Water Abstraction: Implications for Fish and Fisheries     

Limnetic zooplankton run-off a high-head dam and their fate in a river with high current velocity (case of the Krasnoiarsk hydroelectric power station on the Yenisei river

The vertical distribution of net zooplankton in head-water of Krasnoyarsk hydroelectric power station and its horizontal distribution in the tail-water were studied during two years in winter and summer seasons. In order to distinguish living and dead individuals the special staining was used. It was revealed that on average 77% of living plankton pass through high-head dam with deep water scoop to the tailwater. While passing through dam aggregates some individuals of the reservoir plankton are traumatized and die, that results in some increase of portion of dead individuals in the tail water near dam (from 3 to 6%). Alive zooplankton passed through the dam aggregates is eliminated under the Upper Yenisei highly turbulent conditions. There is approximately 10% of it in 32 km from the dam if compare with biomass in 20-40 m layer of reservoir, the portion of dead increases to 11%. The biomass of zooplankton suspended in the water column of the tail-water sometimes increases (till > 1 g/m3) due to large Copepoda Heteroscope borealis, which inhabits near-bottom and near-shore river zones and can be found in the central part of the river during reproductive period. Limnetic zooplankton from the reservoir cannot be considered as important food for planktivores in the tail-water.     

Dams in South Europe: socio-environmental approach and eDNA-metabarcoding to study dam acceptance and ecosystem health

Under current climate warming, dams and reservoirs are main options to ensure water supply in dry regions. However, the presence of these infrastructures encompasses impacts on ecosystem due to the alteration of connectivity and river habitat. We expect that as a result of the relation between water supply as a resource and the population will depend on their use or demand, so the benefits of dams compensate their negative impacts in regions with droughts while not having the same perception in zones where water supply is not a problem, so the public acceptance of dams is expected to change depending on the area. Here, we have employed a multidisciplinary approach to study dam acceptance and also measure ecosystem health in two dammed areas, Guadalhorce and Nalón rivers, Mediterranean dry south and Atlantic humid north of Spain, respectively. The methodology employed has included the use of Environmental DNA for phytoplankton inventory and surveys to stakeholders and ordinary citizens to measure dam’s acceptance. Worse bioindicators of water quality associated to dams were found in Guadalhorce than in Nalon River. However, stakeholders valued more the ecosystem services provided by Guadalhorce dams, especially of cultural nature, than those provided by Nalón dams. Most citizens consulted (N?=?319 and 300 in Guadalhorce and Nalón regions) were favourable to the presence of dams and reservoirs. They would also increase their annual taxes to restore river connectivity, especially in Guadalhorce River, while dam demolition was the least supported. The generally positive views would help to identify actions for improvement of dammed rivers highlighting the importance of restoring river connectivity without dam demolition for local river users.

     

The fish populations of an industrial river in South Wales

The River Sirhowy, a trout river of the Ebbw System in south-east Wales still subject to sporadically high levels of suspended solids derived from the coal mining industry, was investigated over a three year period to assess its importance in the recolonization of a fishless river, the Ebbw Fawr, which is expected to recover from the effects of steelworks effluents discharged near its headwaters. Eight species of fish were recorded. Spawning areas for brown trout ( Salmo trutta L.) were limited by industrial and urban developments and the discharge of suspended solids. Small numbers of native trout were produced in the system and the growth of these fish was poor in the main river, confirming the need for regular stocking. Movements of stocked trout were limited except in the lower reaches of the river where the presence of a native population, high levels of suspended solids and flash floods may have increased the numbers of fish moving into the recovering Ebbw Fawr.     

Assessment of the stocked or wild origin of anadromous brown trout (Salmo trutta L.) in a Danish river system, using mitochondrial DNA RFLP analysis

Declines in the number of anadromous brown trout in the Karup River in Denmark, due to environmental degradation, led to the stocking of large numbers of hatchery trout during the 1980s. This practice was gradually replaced by stocking with the offspring of electrofished local trout The genetic contribution of the hatchery fish to the current population of anadromous trout in the river was estimated by restriction fragment length polymorphism analysis of mitochondrial DNA, using seven restriction endonucleases. Fish from the hatchery strain as well as from five locations in the river system, and from a further unstocked river were screened. Eight haplotypes were observed. The distribution and frequencies of the observed haplotypes revealed little genetic differentiation among stocked populations. The hatchery strain differed significantly from the stocked populations. One haplotype which was found at a high frequency in the hatchery strain was almost absent from the stocked populations. This suggests that the genetic contribution of the hatchery trout to the current population is much less than would be expected from the number of stocked fish. The possible reasons for the failure of the hatchery trout to contribute to the gene pool, and also the implications for conservation biology, are discussed.     

Spatial variation of water temperature characteristics and behavior in a Devon river system

SUMMARY. 1. The results of 5 years of continuous monitoring of river water temperatures at seventeen stations within the Exe basin, Devon, U.K., are presented and discussed.
2. Systematic spatial variation in mean annual water temperature was evident and was strongly related to the topographic variable of elevation. Deviations from this relationship reflect local influences of vegetation shading, runoff source and channel character.
3. Considerable spatial variation in temperature extremes was also apparent, and the Exe basin differs from several other British river systems in exhibiting highest peak temperatures at downstream sites on the mainstream. Discharge from Wimbleball Reservoir exerted a significant influence on annual maxima and minima.
4. A clear seasonal cycle characterized all stations and was objectively defined by second-order harmonic functions which varied in amplitude and phase across the study area. Marked spatial variability in the magnitude and timing of diurnal temperature fluctuations, in temperature duration curves and in accumulated temperatures was also recorded.
5. The implications of the spatial variation in thermal regime for the growth of brown trout was also investigated.     

Effects of hydromorphological integrity on biodiversity and functioning of river ecosystems

River channels tend to a dynamic equilibrium driven by the dynamics of water and sediment discharge. The resulting fluctuating pattern of channel form is affected by the slope, the substrate erodibility, and the vegetation in the river corridor and in the catchment. Geomorphology is basic to river biodiversity and ecosystem functioning since the channel pattern provides habitat for the biota and physical framework for ecosystem processes. Human activities increasingly change the natural drivers of channel morphology on a global scale (e.g. urbanization increases hydrological extremes, and clearing of forests for agriculture increases sediment yield). In addition, human actions common along world rivers impact channel dynamics directly, e.g. river regulation simplifies and fossilizes channel form. River conservation and restoration must incorporate mechanisms of channel formation and ecological consequences of channel form and dynamics. This article (1) summarizes the role of channel form on biodiversity and functioning of river ecosystems, (2) describes spatial complexity, connectivity and dynamism as three key hydromorphological attributes, (3) identifies prevalent human activities that impact these key components and (4) analyzes gaps in current knowledge and identifies future research topics.     

Migrations of sea trout, Salmo trutta L., from the Vardnes river in northern Norway

During the periods 1956–1963 and 1967–1970 traps were operated to catch upstream- and downstream-migrating sea trout, Salmo trutta L. A total of 15 788 sea trout were tagged, using Carlin tags. The number of recaptures made in the traps was 4481, of which 1796 were recaptured more than once.
The distribution of the 2122 recaptures in the sea provides a picture of the sea-migration pattern. Of the sea recaptures, 52.8% were reported as within a distance of 3 km from the river mouth, compared to 0.7% more than 80 km away. All the different size-groups of sea trout were represented among both the long-distance and the short-distance migrants. The results of this study of sea trout migrations are discussed in relation to the published results for Atlantic salmon, Salmo salar L., and sea charr, Salvelinus alpinus (L.), from the same river.
The four highest values recorded for mean distance of daily travel away from the river were 20, 8, 8 and 6km day⁻¹ by smolts and 6, 6, 5 and 5km day⁻¹ by larger-sized sea trout.
Recaptures of tagged sea trout in rivers other than the Vardnes totalled 506, of which 306 had been tagged as smolts. The calculated minimum percentage of stray is 15.5%. The proportion of sea trout from the Vardnes river that actually spawn in other rivers is not known. No significant difference in length distribution was found between the sea trout caught in the Vardnes river and those caught in other rivers. An hypothesis concerning the selective advantages of straying by anadromous salmonids living in small rivers is discussed.     

Responses of riparian trees and shrubs to flow regulation along a boreal stream in northern Sweden

1. Flow dynamics is a major determinant of riparian plant communities. Therefore, flow regulation may heavily affect riparian ecosystems. Despite the large number of dams worldwide, little specific information is available on the longitudinal impacts of dams on vegetation, for example how far downstream and at what degree of regulation a dam on a river can influence riparian woodlands. 2. We quantified the long‐term responses of riparian trees and shrubs to flow regulation by identifying their lateral distribution and habitat conditions along a boreal river in northern Sweden that has been regulated by a single dam since 1948. The regulation has reduced annual flow fluctuations, this effect being largest at the dam, downstream from which it progressively decreases following the entrance of free‐flowing tributaries. 3. We related changes in the distribution patterns, composition, abundance and richness of tree and shrub species to the degree of regulation along the river downstream from the dam. Regulation has triggered establishment of trees and shrubs closer to the channel, making it possible to measure ecological impacts of flow regulation as differences in vegetation attributes relative to the positions of tree and shrub communities established before and after regulation. 4. Trees and shrubs had migrated towards the mid‐channel along the entire study reach, but the changes were largest immediately downstream of the dam. Shrubs were most impacted by flow regulation in terms of lateral movement, but the effect on trees extended furthest downstream. 5. The species composition of trees progressively returned to its pre‐regulation state with distance downstream, but entrance of free‐flowing tributaries and variation in channel morphology and substratum caused local deviations. Species richness after regulation increased for trees but decreased for shrubs. The changes in species composition and richness of trees and shrubs showed no clear downstream patterns, suggesting that other factors than the degree of regulation were more important in governing life form.     

Effects of river flow fluctuations on groundwater discharge through brook trout,Salvelinus fontinalis,spawning and incubation habitats

The effects of short-term fluctuations in river discharge simulating a hydroelectricity peaking regime on the hydrogeological environment of the brook trout's reproductive habitats were examined. Fluctuating river levels altered shallow ( 2.5 m) groundwater pathways, chemistry, and flow potentials within the river bed at spawning and incubation sites. Rising river levels introduced river water into the bank where various degrees of mixing with groundwater occurred. Subsequent recessions of river levels increased the potentials for groundwater flow, particular in an offshore direction. The character of the river water — groundwater interaction appeared to be related to the hydrogeological nature of the river channel and adjacent catchment which varied among sites. The observations suggested hydroelectricity peaking regimes have potential negative impacts on brook trout reproduction.     

Stakeholder involvement in australian paper and packaging waste management LCA study

Intention, Goal, Scope, Background  To discuss the process of stakeholder involvement as undertaken in a post-consumer paper and packaging waste management LCA study conducted during 1997-2001 for the Melbourne Metropolitan Area, Victoria, Australia. Secondly, to present the findings from a survey conducted with the stakeholder groups regarding their perception of involvement in the project. Objectives  To investigate the stakeholder’s perception; and value of being involved in the LCA study intended to generate quantitative environmental information to support debate, development and implementation of waste management practices. Methods  Stakeholders that were involved in the study, both actively and passively, were surveyed by questionnaire Survey findings were analysed in conjunction with stakeholder interaction experiences obtained in the course of the study. as]Results and Discussion Respondents to the survey believed there was a sufficient level of interaction between stakeholders and researchers during the course of the project. The advisory committee approach helped to timely recognize issues and deal with them appropriately. It furdier assisted in the collection of life cycle inventory data and in obtaining ownership of outcomes by the research ream appropriately responding to the needs and issues raised by stakeholders. Recommendations and Outlook  General recommendations for the inclusion of stakeholders in future studies are to use stakeholder interactions, wherever it is possible and practical, which in turn play an educational role, engage stakeholders from the start of the process and allow additional time in the project plan for review stages, as well as ensuring that all relevant groups are represented — industry, industry associations, government and non-governmental organizations, and also provide sufficient material and progress for discussion at meetings.