Seasonal dynamics of three invasive gastropods in urban streams of the Babura River in Medan City, Indonesia

The exponential growth of urban land use in recent decades has led to a significant increase in nutrient loading in urban streams, thereby causing considerable changes in the biological composition of these streams, including the benthic macroinvertebrate community. In the initial stage of our investigation in urban streams of Babura River, Medan City, we discovered the presence of invasive gastropods, namely Melanoides tuberculata, Mieniplotia scabra, and Tarebia granifera, all of which belong to the Thiaridae family. This study focused on evaluating the seasonal assemblages of these three invasive gastropods during the period of March 2017 to January 2018, including both dry and rainy seasons. The abundance of each gastropod varied significantly across sampling periods and seasons, with M. scabra being the most abundant species. The results of the two-way ANOVA indicated that seasonality was a more important factor in influencing the abundance of gastropods compared to differences in species population. Pearson's correlation test showed that the presence of each gastropod was correlated with different environmental parameters, with strong and positive correlations found between M. tuberculata and dissolved oxygen (DO) levels, pH, total dissolved solids (TDS), and velocity during the dry season. Temperature was negatively associated with the abundance of M. scabra and T. granifera during the dry season, and TDS was negatively associated with the abundance of M. tuberculata during the rainy season. Overall, this study provides insights into the ecology of invasive gastropods and their relationship with environmental parameters in Babura River.