Fish passage design for sustainable hydropower in the temperate Southern Hemisphere:An evidence review

The development of hydropower and other infrastructure that disrupts river connectivity poses a serious threat to highly endemic and genetically distinct freshwater fish species in temperate parts of the Southern Hemisphere. Such locations have been neglected in previous reviews on fish passage. Fishways have long been constructed to mitigate the impacts of riverine barriers on fish, yet they have often failed for all but the largest, strongest swimming taxa. This is a particular problem in the temperate south, where the majority of species arewhich is home to native species that are non-recreational and generally small-bodied with weak swimming abilities (e.g. Galaxiidae) relative to typical target species for fishway design (e.g. Salmonidae). Using the Eco Evidence method for rapid evidence synthesis, we undertook an assessment of evidence for effective fishway design focusing on species representative of the temperate south, including eel and lamprey. Systematic literature searches resulted in 630 publications. Through a rigorous screening process these were reduced to 46 publications containing 76 evidence items across 19 hypotheses relating to design criteria for upstream and downstream passage. We found an overwhelming lack of evidence for effective fishway design in the temperate south. Particular deficiencies were found with regard to the design of effective facilities for downstream passage. The attraction and entrance of upstream migrating fish into fishways is also relatively under-researched. Given the urgent need for effective fishways in the temperate south, these results justify an approach to fishway design based on a combination of empirical data and expert knowledge. In the meantime, significant resources should be assigned to improve the evidence base through high quality research. The particular deficiencies identified here could guide that research agenda

Spatiotemporal dynamics of the agricultural landscape mosaic drives distribution and abundance of dominant carabid beetles

International audienceContext Agroecosystems are dynamic, with yearly changing proportions of crops. Explicit consideration of this temporal heterogeneity is required to decipher population and community patterns but remains poorly studied. Objectives We evaluated the impact on the activity-density of two dominant carabid species (Poecilus cupreus and Anchomenus dorsalis) of (1) local crop, current year landscape composition, and their interaction, and (2) inter-annual changes in landscape composition due to crop rotations. Methods Carabids were sampled using pitfall-traps in 188 fields of winter cereals and oilseed rape in three agricultural areas of western France contrasting in their spatial heterogeneity. We summarized landscape composition in the current and previous years in a multi-scale perspective, using buffers of increasing size around sampling locations. Results Both species were more abundant in oilseed rape, and in landscapes with a higher proportion of oilseed rape in the previous year. P. cupreus abundance was negatively influenced by oilseed rape proportion in the current year landscape in winter cereals and positively by winter cereal proportion in oilseed rape. A. dorsalis was globally impacted at finer scales than P. cupreus. Conclusions Resource concentration and dilution-concentration processes jointly appear to cause transient dynamics of population abundance and distribution among habitat patches. Inter-patch movements across years appear to be key drivers of carabids’ survival and distribution, in response to crop rotation. Therefore, the explicit consideration of the spatiotemporal dynamics of landscape composition can allow future studies to better evidence ecological processes behind observed species patterns and help developing new management strategies

Lamprey spawning migration

During recent decades, new insights regarding the spawning migration of lampreys have been gained due to advances in technology and growing interest in this key life history phase. The development of miniaturized active and passive transmitters has led to detailed information on the timing and extent of lamprey migrations. These tools, together with sophisticated laboratory experiments, have provided fertile ground for studies of lamprey migratory physiology and behavior. New molecular tools have been applied to questions of population structure and philopatry, while the identification of lamprey pheromones has illuminated heretofore unimagined mechanisms of migration and orientation. Interest in spawning migration has been spurred by the growing need to restore native lamprey populations and the equally pressing need to control invasive sea lamprey in the Laurentian Great Lakes. While important advances in anadromous lamprey biology have been achieved, gaps remain in our understanding of marine movements, species-specific differences, mechanisms of orientation, and the factors controlling passage success. Moreover, with the exception of the landlocked sea lamprey in the Great Lakes, research on the spawning migrations of the strictly potamodromous species (i.e., those that are parasitic in fresh water and the non-parasitic “brook” lampreys) is sorely lacking, seriously compromising our ability to assess what constitutes barriers to their migration