This paper synthesises published literature on run-of-river hydropower, highlighting its potential to affect both the physical and ecological conditions of river systems. The paper considers the limited number of direct studies and reviews a wider literature on the two principal impacts of such schemes on river systems: the introduction or maintenance of in-channel barriers and water abstraction/flow regime alteration. We outline how river systems are likely to be impacted by such schemes and identify the key issues arising from their continued development. Potential mitigation approaches are highlighted and the areas of future research required to adequately address current knowledge gaps are identified.

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A study was instigated to test whether grazing herbivores have evolved effective strategies to reduce parasite ingestion and to assess the effects of parasitism on these strategies. Two choice trials, each using five animals parasitized with O. circumcincta and five parasite naive animals, were conducted to investigate cues used by sheep to avoid grazing swards contaminated with faeces. Animals were presented with pairs of artificial swards (36 × 21 cm) and allowed to graze for short periods. In the first trial, four quantities (0 g, 5 g, 15 g and 25 g), and in the second trial a control (no faeces) and three age classes (0, 10 and 21 days old), of faeces were tested against each other. Increasing amount offaeces per sward tray was associated with a reduced proportion of bites taken from the sward and reduced bite depth and mass. The minimum amount of faeces at which sheep showed significant levels of rejection was 15 g. Decreasing age of faeces was associated with a reduced proportion of bites taken from the sward, reduced bite depth and mass. This presented the paradox that grazing swards contaminated with young faeces presented least risk of parasitism, yet fresh faeces presented the strongest stimulus for sward rejection. Parasitism altered animal grazing behaviour with parasitized animals becoming more selective when avoiding contaminated swards, taking smaller bites at reduced bite rates compared with non-infected animals. The enhancement of faeces avoidance behaviours shown by parasitized animals could act to reduce further intake of parasites and suggests that grazing behaviour is affected by nematode infection.

Key Words induced technical change, energy-environment-economy modelss Abstract Technical change in the energy sector is central for addressing longterm environmental issues, including climate change. Most models of energy, economy, and the environment (E3 models) use exogenous assumptions for this. This is an important weakness. We show that there is strong evidence that technical change in the energy sector is to an important degree induced by market circumstances and expectations and, by implication, by environmental policies such as CO 2 abatement. We classify the main approaches to modeling such induced technical change and review results with particular reference to climate change. Among models with learning by doing, weak responses are only obtained from models that are highly aggregated (lack technological diversity) and/or that equate rates of return to innovation across sectors. Induced technical change broadens the scope of efficient policies toward mitigation, including not just research and development and aggregated market instruments but a range of sectoral-based policies potentially at divergent marginal costs. Furthermore, to the extent that cleaner technologies induced by mitigation diffuse globally, a positive spillover will result that will tend to offset the substitution-based negative spillover usually hypothesized to result from the migration of polluting industries. Initial explorations suggest that this effect could also be very large.

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