IGB runs a long-term monitoring programme to measure environmental conditions and the presence and abundance of selected organisms in four focus and several additional freshwater bodies in Northeast Germany. These data, some of which are available for more than 40 years and with a high temporal resolution, provide a unique basis for research on the response of freshwater bodies to changing conditions such as nutrient loading, climate warming or invasions of non-native species. Each parameter has a responsible scientist at the Institute who can be contacted for potential collaborations. The CTP Long-term Monitoring provides a platform to discuss data, monitoring parameters, sampling procedures and methods, and to stimulate research and collaboration.