No abstract

Although the practice of cultivating mass fl owering crops (MFCs) is seen as a means of counteracting the widespread decline of insect pollinators, no study to-date has evaluated whether the increased pollinator abundance associated with MFCs infl uences pollinator visits to assemblages of adjacent native, non-crop plant species (pollinator ' spill-over ' ). In this study we quantifi ed bumblebee abundance along hedgerow transects in MFC (fi eld bean) vs non-MFC (wheat) margins. Surveys were conducted on east and west-facing margins twice daily (morning and afternoon) for three or four days during the main MFC fl owering period (June) over four years involving paired bean and wheat fi elds in Devon and Cornwall, southwest England. Although no single bumblebee species showed any consistent change in relative frequency, when taken across all years and bumblebee species combined, we observed twice as many bumblebees visiting fl owers adjacent to the MFC. However, when we compared bumblebee activity along hedgerow transects two weeks after bean fl owering, there was no diff erence between crops. We thus conclude that although there is evidence for pollinator spillover from the bean MFC to nearby semi-natural habitat, the eff ect is comparatively short lived and not specifi c to any single bumblebee species. We also suggest that while pollinator services to native plant species might be briefl y enhanced by MFC cultivation, the possible repercussions of bumblebee spill-over from MFCs to semi-natural habitats and the other pollinator groups they support should be evaluated before MFC cultivation is considered as a means of conserving declining bumblebee populations.

No abstract

Populations of the European shads Alosa alosa (Linnaeus, 1758) and Alosa fallax Lacépède, 1800 (Alosa spp.) are protected under legislation because of their vulnerability to human disturbances. In particular, river impoundments block their upstream migration, preventing access to spawning areas. Knowledge on the spatial extent of their spawning is important for informing conservation and river management plans. Determining the spatial extent of Alosa spp. spawning is challenging. They enter rivers over a 2‐3‐month period and the species potentially migrate different distances upstream. Capture and handling can be problematic, spawning events generally occur at night, and kick‐sampling for eggs is limited to shallow water. Assessing their spatial extent of spawning could, however, incorporate non‐invasive sampling tools, such as environmental DNA (eDNA). An eDNA assay for Alosa spp. was successfully developed, based on the cytochrome c oxidase subunit I gene segment and quantitative polymerase chain reaction (qPCR). Application in spring 2017 to the River Teme (River Severn catchment, western England) revealed high sensitivity in both laboratory and field trials. Field data indicated Alosa spp. spawning between May and June, with migrants mainly restricted to areas downstream of the final impoundment. eDNA can thus be used as a non‐invasive sampling tool to determine the freshwater distribution of these fishes in Europe, enhancing their conservation at local and regional scales.