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Dispersal is a main determinant of community assembly. Landscape configurations of rivers, lakes, or ponds are often independently considered in this framework. However, these systems share species conforming to a waterscape with different environments coupled by dispersal. While empirical results support a main role of this coupling on biodiversity organization, it is difficult to assess its importance at large geographic scales. Using a theoretical approach, we quantified the potential role of dispersal through different freshwater ecosystems of the United Kingdom and Ireland on biogeographic diversity patterns. We implemented a coalescent model considering 11,131 communities connected by distance-dependent dispersal and with species that have different performances for recruitment in three different aquatic habitats. Biogeographic diversity patterns were estimated for each habitat alone or for the whole waterscape combining ephemeral, temporal, and permanent waters. The results indicated that the coupling between different types of environments fostered local diversity, in a magnitude that increased from the ephemeral to permanent waters and from poorer to richer communities. Furthermore, a strong spatial structure in the potential effect of dispersal among different freshwater environments was observed, indicating that freshwater biogeography was likely determined by the connection among freshwater ecosystems to a larger extent than previously thought. [ABSTRACT FROM AUTHOR]

There is increasing focus on the frequency of jellyfish blooms in the Northeast Atlantic because of negative interactions with humans. However, uncertainty exists as to whether perceptions of increasing bloom frequencies reflect reality due to limitations within long-term population trend data. This study, therefore, developed and applied a semi-quantitative mapping approach to visualise bloom suitability based on the physiological tolerances of seven jellyfish to ocean temperature, salinity and a prey index across the Northeast Atlantic. A 10% increase and a 10% decrease in the environmental parameters was then applied to the maps to assess model sensitivity and the potential influence of environmental change on bloom suitability. The study found that optimal physiological temperatures and salinities combined with peaks in prey abundance drove higher bloom suitability and determined distribution. Several locations predicted to be at high risk of bloom occurrence off British and Irish coasts were found to coincide with areas of high anthropogenic activity that could be impacted by blooms. In the absence of long-term datasets on jellyfish population dynamics, the results and methods developed in this study allow an understanding of historic bloom events and predictions of future populations that will be useful in informing monitoring and management. [ABSTRACT FROM AUTHOR]