Impacts of climate change, land-use change and phosphorus reduction on phytoplankton in the River Thames (UK)

• Published in: The Science of the total environment Vol. 572; pp. 1507 - 1519
• Main Authors: Bussi, Gianbattista, Whitehead, Paul G., Bowes, Michael J., Read, Daniel S., Prudhomme, Christel, Dadson, Simon J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2016
• Subjects: Agriculture; Climate Change; Cyanobacteria; England; Land use change; Models, Theoretical; Phosphorus - analysis; Phytoplankton - physiology; Phytoplankton modelling; River Thames; River water quality; Rivers - chemistry; Scenario-neutral approach; Water Pollutants, Chemical - analysis; British Isles, England; British Isles, England, Thames R; River water quality; Phytoplankton modelling; Climate change; Scenario-neutral approach; River Thames; Land use change
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2016.02.109

Potential increases of phytoplankton concentrations in river systems due to global warming and changing climate could pose a serious threat to the anthropogenic use of surface waters. Nevertheless, the extent of the effect of climatic alterations on phytoplankton concentrations in river systems has not yet been analysed in detail. In this study, we assess the impact of a change in precipitation and temperature on river phytoplankton concentration by means of a physically-based model. A scenario-neutral methodology has been employed to evaluate the effects of climate alterations on flow, phosphorus concentration and phytoplankton concentration of the River Thames (southern England). In particular, five groups of phytoplankton are considered, representing a range of size classes and pigment phenotypes, under three different land-use/land-management scenarios to assess their impact on phytoplankton population levels. The model results are evaluated within the framework of future climate projections, using the UK Climate Projections 09 (UKCP09) for the 2030s. The results of the model demonstrate that an increase in average phytoplankton concentration due to climate change is highly likely to occur, with the magnitude varying depending on the location along the River Thames. Cyanobacteria show significant increases under future climate change and land use change. An expansion of intensive agriculture accentuates the growth in phytoplankton, especially in the upper reaches of the River Thames. However, an optimal phosphorus removal mitigation strategy, which combines reduction of fertiliser application and phosphorus removal from wastewater, can help to reduce this increase in phytoplankton concentration, and in some cases, compensate for the effect of rising temperature. [Display omitted] •Both climate and land-management changes have an impact on phytoplankton.•The phytoplankton response to climatic and land-management changes was estimated.•An increase in phytoplankton concentration due to climate change is likely to occur.•Cyanobacteria are more sensitive to climatic changes than other phytoplankton groups.•P reduction can help alleviate the effects of climate change on phytoplankton.