Melting glaciers are releasing great amounts of fine particles, the so-called glacial flour (“Gletschermilch”) organic carbon and nutrients such as phosphorus and nitrogen that have an enormous impact on glacier-fed streams and lakes. Increasing nutrient and particle concentrations can stimulate the bacterial communities of recipient proglacial lakes. However, the particular effects of glacial meltwater and its different constituents on lake bacterial communities are not completely understood. Here, I aimed to assess the short- and long-term effects of different glacial meltwater components on the bacterial abundance of Austrian proglacial lakes and of a clear-water alpine lake. The effects of glacial meltwaters on the bacterial abundance of proglacial- and clear-water alpine lakes were tested by establishing in situ incubations with various meltwater components of the same meltwater (unfiltered-, filtered meltwater or glacial particles) and the respective lake waters or with various meltwaters and the alpine lake Gossenköllesee, not influencedby glacial meltwater. The cultures were incubated for 7 days at in situ temperature (12C) and changes in bacterial abundance were tracked by flow cytometry and nucleic staining. Bacterial abundance increased in all the treatments including the control for both incubation experiments over time. Hence, no differences among the meltwater components and the different meltwaters could be detected. Overall, our study revealed that under the chosen experimental conditions the studied glacial meltwaters did not affect the bacterial abundance of the recipient lakes. Short-term experiments to test the uptake by, or release of, phosphate from glacial particles showed equilibrium concentrations of 5 to 10 g soluble reactive phosphorus per liter.