Impacts of hydropeaking: A systematic review

Hydropower is commonly considered a renewable energy source. Nevertheless, this does not imply an absence of impacts on the riverine ecosystem, the extent of which is expected to increase in the coming years due to the energy transition from fossil fuels to renewable sources and for the climate change. A common consequence of hydroelectric power generation is hydropeaking, which causes rapid and frequent fluctuations in the water flow downstream of hydropower plants. The review incorporates 155 relevant studies published up until November 2023 and follows a systematic review method, Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), which is a multi-stage systematic procedure for the identification and selection of research documents. The selected studies highlighted several prominent impacts of hydropeaking on aquatic environments. The primary effects include alterations in flow patterns, modification of water temperature, changes in sediment dynamics and fluctuations in dissolved gas levels. These alterations have been found to affect various aspects of aquatic ecosystems, including fish growth, behavior, reproductive success, habitat, and migration patterns, and benthic macroinvertebrate communities. Furthermore, hydropeaking can also lead to habitat fragmentation, erosion, and loss of riparian vegetation, thereby impacting terrestrial ecosystems that depend on the aquatic environment. Despite the body of literature reviewed, several knowledge gaps were identified, underscoring the need for further research. There is limited understanding of the long-term ecological consequences of hydropeaking and its cumulative effects on aquatic ecosystems. Additionally, there is lack of consensus regarding the quantification of ecosystem services, economic impact, soil moisture content, and weighted usable area due to flow fluctuation and global evolution of energy production from renewable energy sources. Addressing the identified research gaps is crucial for achieving a balance between energy production and the conservation of freshwater ecosystems in the context of a rapidly changing global climate.

[Rare metastases]

The paper reports a number of cases of uncommon metastasis confirmed by histological tests in surgical biopsies; following a brief discussion of the literature on this topic and in particular on the basis of an earlier study by one of the authors, the paper affirms that metastasis is related to general and local biological factors, that the diffusion of neoplastic cells is an early and generalised phenomenon opposed by organic defence mechanisms, and that the concept of uncommon metastasis should be revised, without resorting to fixed anatomical references, according to a general "impregnation" of tumour cells.

[Long-term results of the surgical treatment of ileo-colonic Crohn disease]

18 patients with Crohn's disease primarily treated with excisional surgery were studied. The crude recurrence and reoperation rate were analyzed. The influence of sex, age and length of history prior to operation was in this respect also studied.