Herpetofauna are the most vulnerable vertebrate animal groups in the world. The vulnerability is mainly related to their affinity to specific environmental conditions, prone to only known interspecific interactions (competition, prey-predator relationship, host-parasite relationship, etc.), and special physiological features. Thus, even a very little change in ecological setups, such as climate change, the introduction of new species, or encountering any element that may hamper their physiological processes, can be detrimental. Being one of the global pet trade epicenters and having traces of microplastic (MP) pollution in nature, South Korea is likely to face two of the major herpetofaunal conservation challenges from the impacts of alien invasive species and MPs in near future. Many alien turtle species are being reported from the wild and many (e.g., Trachemys scripta; TS and Pseudemys concinna; PC) are being announced as ecosystem disturbance species. On the other hand, although the accumulation and impacts of MPs remained unstudied in South Korea, herpetofauna with MP accumulation are being reported across the world and are considered one of the major threats. Hence, we plan to study- (i) the growth rates of two widely distributed invasive turtles, TS and PC, with different food items to measure the potentiality to compete and suppress the threatened native species population, and (ii) to evaluate MP accumulation in Lithobates catesbeianus (LC). We found the highest growth rate of TS with meat, whereas, PC with mixed foods. It indicates TS has a higher potentiality to compete and suppress the threatened native freshwater turtles, Mauremys reevesii as they overlap the food habits. Furthermore, we have identified three potential reservoirs from each of the city, village, and remote areas, which harbor LC, and possibly are contaminated by MPs, to see MP accumulation. This study is very important to set management policies for TS and PC. It will also help in battling against microplastic pollution, the most potential herpetofaunal conservation threat in the coming days.