What else do managers need to know about warming rivers? A United Kingdom perspective: Managing warming rivers

River flow and water temperature are fundamental controls of freshwater ecosystems. Hence, future warming could impact valued habitats and species, particularly those with cold water preferences (such as salmonids). Warming could also exacerbate existing environmental pressures or diminish the effectiveness of management interventions. Climate model projections provide compelling evidence of the need for adaptation despite uncertainty about the timing, nature, and distribution of impacts on water quality, vulnerable species, and habitats. Low‐regret adaptation options to manage temperature impacts include increasing riparian shade, enhancing thermal refugia, and removing thermal barriers or hotspots. Indirect controls include managing river flows through abstraction and discharge regulation, moderating flow control structures, and manipulating channel hydromorphology. However, fundamental gaps in understanding may limit the effectiveness of some of these measures, leading to undesired side effects, wasted resources, ineffectual outcomes, or limited uptake. These knowledge gaps include where to target measures, how to implement in different situations, how to maximize co‐benefits and integrate with other policy objectives, and how to support implementation across rural and agricultural landscapes. Despite many uncertainties, restoration of riparian shade and river flows has the potential to deliver multiple benefits even if this does not include retarding rates of warming. WIREs Water 2015, 2:55–64. doi: 10.1002/wat2.106

Existing and emerging cyanocidal compounds: new perspectives for cyanobacterial bloom mitigation

To help ban the use of general toxic algicides, research efforts are now directed towards the discovery of compounds that are specifically acting as cyanocides. Here, we review the past and look forward into the future, where the less desirable general algicides like copper sulphate, diuron or endothall may become replaced by compounds that show better specificity for cyanobacteria and are biodegradable or transform into non-toxic products after application. For a range of products, we review the activity, the mode of action, effectiveness, durability, toxicity towards non-target species, plus costs involved, and discuss the experience with and prospects for small water volume interventions up to the mitigation of entire lakes; we arrive at recommendations for a series of natural products and extracted organic compounds or derived synthetic homologues with promising cyanocidal properties, and briefly mention emerging nanoparticle applications. Finally, we detail on the recently introduced application of hydrogen peroxide for the selective killing of cyanobacteria in freshwater lakes