Nutrient and light limitation of periphyton in the River Thames: implications for catchment management

Soluble reactive phosphorus (SRP) concentrations in the River Thames, south east England, have significantly decreased from an annual maximum of 2100 μg l−1 in 1997 to 344 in 2010, primarily due to the introduction of phosphorus (P) removal at sewage treatment works within the catchment. However, despite this improvement in water quality, phytoplankton biomass in the River Thames has greatly increased in recent years, with peak chlorophyll concentrations increasing from 87 μg l−1 in the period 1997 to 2002, to 328 μg l−1 in 2009. A series of within-river flume mesocosm experiments were performed to determine the effect of changing nutrient concentrations and light levels on periphyton biomass accrual. Nutrient enrichment experiments showed that phosphorus, nitrogen and silicon were not limiting or co-limiting periphyton growth in the Thames at the time of the experiment (August–September 2010). Decreasing ambient SRP concentration from 225 μg l−1 to 173 μg l−1 had no effect on periphyton biomass accrual rate or diatom assemblage. Phosphorus limitation became apparent at 83 μg SRP l−1, at which point a 25% reduction in periphyton biomass was observed. Diatom assemblage significantly changed when the SRP concentration was reduced to 30 μg l−1. Such stringent phosphorus targets are costly and difficult to achieve for the River Thames, due to the high population density and intensive agriculture within the Thames basin. Reducing light levels by shading reduced the periphyton accrual rate by 50%. Providing shading along the River Thames by planting riparian tree cover could be an effective measure to reduce the risk of excessive algal growth. If the ecology of the Thames is to reach the WFD's “good ecological status”, then both SRP concentration reductions (probably to below 100 μg l−1) and increased shading will be required

Selecting Core Outcomes for Randomised Effectiveness trials In Type 2 diabetes (SCORE- IT): A patient and healthcare professional consensus on a core outcome set for type 2 diabetes

Objectives Heterogeneity in outcomes measured across trials of glucose-lowering interventions for people with type 2 diabetes impacts on the ability to compare findings and may mean that the results have little importance to healthcare professionals and the patients that they care for. The SCORE-IT study (Selecting Core Outcomes for Randomised Effectiveness trials In Type 2 diabetes) has addressed this issue by establishing consensus on the most important outcomes for non-surgical interventions for hyperglycemia in type 2 diabetes.Research design and methods A comprehensive list of outcomes was developed from registered clinical trials, online patient resources, qualitative literature and long-term studies in the field. This list was then scored in a two-round online Delphi survey completed by healthcare professionals, people with type 2 diabetes, researchers in the field and healthcare policymakers. The results of this online Delphi were discussed and ratified at a face-to-face consensus meeting.Results 173 people completed both rounds of the online survey (116 people with type 2 diabetes, 37 healthcare professionals, 14 researchers and 6 policymakers), 20 of these attended the consensus meeting (13 people with type 2 diabetes and 7 healthcare professionals). Consensus was reached on 18 core outcomes across five domains, which include outcomes related to diabetes care, quality of life and long-term diabetes-related complications.Conclusions Implementation of the core outcome set in future trials will ensure that outcomes of importance to all stakeholders are measured and reported, enhancing the relevance of trial findings and facilitating the comparison of results across trials