Effect of Temperature, Nutrients and Diuron on Freshwater River Biofilms: A Statistical Approach

Abstract

The influence of riverine physicochemical factors on the overall physiological status and growth of river biofilms was established in a field-data-based model. Two sampling stations were located in the intermediate and downstream watershed areas of the river Morcille (France). Water temperature, suspended matter (SM), dissolved organic carbon (DOC), nutrients (NH4, NO2, NO3, PO4, Si) and toxicant (herbicide diuron) concentrations in the river were used as independent variables for modeling their effect on biofilm photosynthetic (PS) yield and dry weight (dependent variables). Basis function of fifth-degree polynomial to accommodate the non-linear associations between the dependent variables and each of the independent variables followed by multiple linear regression was applied to determine the two endpoints. Data from September 2008 to December 2011 were utilized for model development, and 2011 data were used for model validation. Nutrients and DOC, rather than diuron, had a significant influence (p < 0.05) on PS yield and dry weight. This model, therefore, integrated the interaction between co-occurring physicochemical factors and pollutantto understand the dynamics of biofilm growth.

Keywords

• biofilm
• diuron
• temperature
• nutrients
• basis function
• regression model