Nutrient Loading, Temperature and Heat Wave Effects on Nutrients, Oxygen and Metabolism in Shallow Lake Mesocosms Pre-Adapted for 11 Years

Global changes (e.g., warming and population growth) affect nutrient loadings temperatures, but global also results in more frequent extreme events, such as heat waves. Using data from the world’s longest-running shallow lake experimental mesocosm facility, we studied effects of different levels combined with varying which included a simulated 1-month summer wave (HW), on oxygen concentrations, gross ecosystem primary production (GPP), respiration (ER), net (NEP) bacterioplankton (BACPR). The mesocosms had two (high (HN) low (LN)) three temperatures according to IPCC 2007 scenarios (unheated, A2 + 50%) that were applied for 11 years prior present experiment. HW consisted 5 °C extra temperature increases only 50% treatments 1 July August 2014. Linear mixed effect modeling revealed strong treatment concentration chlorophyll (Chl-a), various forms phosphorus nitrogen well percentage (24 h means). Applying full dataset, found significant positive loading GPP, ER, NEP BACPR, ER BACPR. GPP ER. When dividing into LN HN, Chl-a orthophosphate HN. models differential nutrients, macrophyte abundance (PVI) metabolism variables, PVI being particularly important mesocosms. All variables responded strongly cooling-low irradiance event middle HW, resulting severe drop not least HN heated Our demonstrate nutrients an overall rapid response BACPR temperature, including HWs, making them sensitive indicators climate warming.