Periphyton response to nutrient addition in 3 lakes of different benthic productivity

AbstractNutrient-diffusing substrata were used to determine if periphyton communities in lakes of different benthic productivity respond similarly to nutrient inputs, and if their responses corresponded with inference models developed from a calibration set of 32 Irish lakes. In addition, the attributes of the periphyton community most effective for detecting changes in periphyton associated with nutrient addition were examined. P-addition treatments had significantly higher algal biovolume than N-addition or control treatments. Canonical correspondence analysis using nominal variables to define treatments indicated that both nutrient addition and lake (= benthic productivity) significantly affected taxonomic composition and the proportion of algal growth forms. The more productive lakes had a greater relative abundance of filamentous chlorophytes, cyanobacteria, and mobile and stalked diatoms. Within lakes, nutrient addition was associated with an increase in filamentous chlorophytes and decreases in non...