Abstract:[Objectives] Bats are crucial for the maintenance of ecosystems, but they also rely on good environmental water sources for their survival. However, there is a lack of research on whether anthropogenically disturbed water environments, particularly urban aquatic ecology and environmental factors, influence bat water utilization. This study aims to provide basic data for the conservation of urban bats by investigating the correlation between aquatic ecology and environmental factors and bat activity in Changchun, China. [Methods] From June to August 2023, bat echolocation calls were recorded at 25 lakes and 6 rivers in the urban area of Changchun (Fig. 1). The study simultaneously recorded 17 ecological and environmental factors of aquatic ecosystems, including those common to both lakes and rivers, such as total number of insects around the water, number of Lepidoptera, Coleoptera, and Diptera in the vicinity, average atmospheric temperature, humidity, and wind speed around the water, chemical oxygen demand, ammonia nitrogen content, pH, dissolved oxygen content, average noise level around the water, and average luminance of the sampling sites. Additionally, lake-specific factors were recorded, including lake area, shape, vegetation coverage around the lake, and the functional zone of the lake. Experiments were conducted for 10 d each in June and July, and for 11 d in August, with each experiment starting at sunset and lasting 3 h. The experiments included acoustic sampling and monitoring of aquatic ecological and environmental factors. One sampling site was selected for each water body, and only one experiment was conducted at each site. In Avisoft-SASlab Lite software, the dominant frequency of bat echolocation calls was used to distinguish bat species. The number of echolocation pulse sequences of bats was used as a proxy for bat activity, and generalized linear models (GLM) and generalized additive models (GAM) were employed to examine the effects of aquatic ecological and environmental factors on bat activity. [Results] In Changchun, four bat species were found in the aquatic environment:Pipistrellus abramus, Hypsugo alaschanicus, Vespertilio sinensis, and Myotis ikonnikovi. M. ikonnikovi was excluded from subsequent analysis due to the relatively low number of echolocation pulse sequences. The average atmospheric temperature around the water was significantly positively correlated with the total number of echolocation pulse sequences for the three bat species (P < 0.001) and H. alaschanicus (P < 0.001). The average atmospheric humidity around the water was significantly positively correlated with the total number of echolocation pulse sequences of the three bat species (P < 0.05) and V. sinensis (P < 0.001). The pH value of the water was significantly negatively correlated with the total number of echolocation pulse sequences of the three bat species (P < 0.001) and H. alaschanicus (P < 0.05). The ammonia nitrogen content in the water was significantly negatively correlated with the echolocation pulse sequences of V. sinensis (P < 0.05). The average luminance of the sampling sites was significantly positively correlated with the echolocation pulse sequences of V. sinensis (P < 0.05, Fig. 2). Lake area was significantly negatively correlated with the total number of echolocation pulse sequences of the three bat species (P < 0.01), H. alaschanicus (P < 0.05), and V. sinensis (P < 0.01). The shape of the Lake was significantly negatively correlated with the echolocation pulse sequences of V. sinensis (P < 0.001, Fig. 3). In lakes in leisure areas, there were significant differences in the total number of echolocation pulse sequences of the three bat species (P < 0.05), H. alaschanicus (P < 0.01), and P. abramus (P < 0.05) compared to residential areas. There was also a significant difference in the echolocation pulse sequences of P. abramus (P < 0.05) in lakes in educational areas compared to residential areas (Table 1). The average total number of echolocation pulse sequences of the three bat species in lakes in residential areas was 2.6 times that in lakes in leisure areas. The average number of echolocation pulse sequences of H. alaschanicus in lakes in residential area was 3.1 times that in lakes in leisure areas. The average number of echolocation pulse sequences of P. abramus in residential area lakes was 3.2 times that in leisure areas lakes and 4.6 times that in educational area lakes (Table 2). [Conclusion] The study results indicate that urban aquatic ecology and environmental factors can influence bat activity. It is recommended to focus on urban water environments to better protect bat diversity in cities.