Ecological impacts of small hydropower plants on headwater stream fish: From individual to community effects

Benejam L., Saura-Mas S., Bardina M., Sola C., Munne A., Garcia-Berthou E. (2015) Ecological impacts of small hydropower plants on headwater stream fish: From individual to community effects. Ecology of Freshwater Fish. : 0-0.
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Doi: 10.1111/eff.12210

Resum:

Hydroelectricity is increasingly used worldwide as a source of renewable energy, and many mountain ranges have dozens or hundreds of hydropower plants, with many more being under construction or planned. Although the ecological impacts of large dams are relatively well known, the effects of small hydropower plants and their weirs have been much less investigated. We studied the effects of water diversion of small hydropower plants on fish assemblages in the upper Ter river basin (Catalonia, NE Spain), which has headwater reaches with good water quality and no large dams but many of such plants. We studied fish populations and habitat features on control and impacted reaches for water diversion of 16 hydropower plants. In the impacted reaches, there was a significantly lower presence of refuges for fish, poorer habitat quality, more pools and less riffles and macrophytes, and shallower water levels. We also observed higher fish abundance, larger mean fish size and better fish condition in the control than in impacted reaches, although the results were species-specific. Accordingly, species composition was also affected, with lower relative abundance of brown trout (Salmo trutta) and Pyrenean minnow (Phoxinus bigerri) in the impacted reaches and higher presence of stone loach (Barbatula quignardi) and Mediterranean barbel (Barbus meridionalis). Our study highlights the effects of water diversion of small hydropower plants from the individual to the population and community levels but probably underestimates them, urging for further assessment and mitigation of these ecological impacts. © 2014 John Wiley & Sons A/S.

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Could electric fish barriers help to manage native populations of European crayfish threatened by crayfish plague (Aphanomyces astaci)?

Benejam L., Saura-Mas S., Montserrat J., Torres F., Macies M. (2015) Could electric fish barriers help to manage native populations of European crayfish threatened by crayfish plague (Aphanomyces astaci)?. Management of Biological Invasions. 6: 307-310.
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Doi: 10.3391/mbi.2015.6.3.10

Resum:

Crayfish plague (Aphanomyces astaci) is the main problem that hinders the conservation of European crayfish species. Every year, dozens of native crayfish populations disappear due to this disease. We used an electric fish barrier to block the dispersal of infected crayfish upstream. One of the main objectives of this communication is to transfer our expertise using this equipment for improved conservation outcomes. As a result, we report a detailed description of the experience, as well as requirements, problems and opportunities of using an electric fish barrier to try to control crayfish plague in-situ. © 2015 The Author(s) and 2015 REABIC.

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Connectivity conservation priorities for individual patches evaluated in the present landscape: How durable and effective are they in the long term?

Rubio L., Bodin O., Brotons L., Saura S. (2015) Connectivity conservation priorities for individual patches evaluated in the present landscape: How durable and effective are they in the long term?. Ecography. 38: 782-791.
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Doi: 10.1111/ecog.00935

Resum:

One of the most widespread approaches for setting spatially-explicit priorities for connectivity conservation consists in evaluating the effects of the individual removal of each habitat patch (one at a time) from the landscape. It however remains unknown the degree to which such priorities are valid and reliable in the longer term, as subsequent habitat losses and other disruptions accumulate in the landscape. We compared the patch prioritizations and estimated connectivity losses resulting from individual patch removals and from a more exhaustive assessment accounting for the potentially synergistic impacts of multiple habitat losses by testing all possible combinations of patch removals. Habitat availability (reachability) metrics and metapopulation capacity were calculated in purposefully simulated landscapes and in habitat distribution data for three bird species (NE Spain). We found that 1) individual patch removals allowed identifying areas of low contribution to connectivity that remained so after subsequent network modifications, 2) the most important patches identified through individual removals often did not coincide with those patches whose removal would actually be most detrimental after multiple habitat losses. However, these differences were smaller for the habitat reachability metrics, as well as for very mobile species that were largely insensitive to habitat spatial arrangement. If many patch losses over time are likely, it might be a more robust and fruitful conservation strategy for managers to pinpoint those patches that, with a low negative impact on connectivity, can be converted to other land uses, instead of trying to elucidate through individual patch removals which subset of protected patches would be the most effective for conserving as much connectivity as possible in the long term. Individual patch removals provide useful but non-permanent guidelines that may need to be reassessed when substantial landscape modifications occur, which requires dynamic strategies for connectivity conservation in the face of global change. © 2014 The Authors.

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