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

Abstract

Article (refereed) -postprintBussi, Gianbattista; Whitehead, Paul G.; Bowes, Michael J.; Read, Daniel S.; Prudhomme, Christel; Dadson, Simon J. 2016. Impacts of climate change, land-use change and phosphorus reduction on phytoplankton in the River Thames (UK).Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. AbstractPotential 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 scenarioneutral 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.

Assessment of Risks to Public Water Supply From Low Flows and Harmful Water Quality in a Changing Climate

“…To assess the impacts of land use and land management on the water quality, three scenarios were defined: (i) LU‐baseline: current land use; (ii) LU‐future: future land use, that is, expansion of agricultural land due to increased food demand; and (iii) LU‐future + mitigation: future land use with enhanced phosphorus mitigation strategies. These scenarios are consistent with the ones used in Bussi, Whitehead, et al (). The future land use scenario (ii) describes an increase in agricultural land area.…”

Hydrological and environmental variables outperform spatial factors in structuring species, trait composition, and beta diversity of pelagic algae

“…For example, some studies found that the geographical topography (e.g., altitude, latitude, and longitude) and climate were the dominant factors regulating algae variation (Bae et al., ; Tang, Niu, et al., ; Tang, Wu, et al., ; Wu et al., ). In contrast, local environmental variables (e.g., substrate composition, sediments, nutrients, oxygen contents, and biointeraction) were often considered to be the main regulating factors (Bae et al., ; Bussi et al., ). Besides, previous studies have rarely taken hydrological variables into consideration.…”

“…The relationships were statistically significant according to the Mantel test (9,999 permutations, p < .05, see Table 3). Regression lines based on linear models are shown by solid blue lines, and shaded gray area indicates 95% confidence interval of the fit factors (Bae et al, 2014;Bussi et al, 2016). Besides, previous studies have rarely taken hydrological variables into consideration.…”

Using a Scenario‐Neutral Framework to Avoid Potential Maladaptation to Future Flood Risk

“…Authorities are also using allowances to investigate community vulnerability and to inform adaptive approaches to risk management (OPW, ). “Scenario‐neutral” (SN) approaches are increasingly employed to evaluate these potential climate change impacts on water and environmental systems (Brown & Wilby, ; Bussi, Dadson, et al, ; Bussi, Whitehead, et al, ; Culley et al, ; Guo et al, ; Prudhomme et al, , ; Vormoor et al, ; Whateley et al, ). SN approaches involve testing the responsiveness of a local indicator (e.g., reservoir levels) to incremental adjustments in key driving climate variables (e.g., temperature, rainfall), across a plausible range of changes in variable intensity and seasonality.…”