Assessment of environmental DNA for invasive freshwater turtle at Yeonhwaji pond in Jeju Island, South Korea.

다국어 초록 (Multilingual Abstract)

Environmental DNA (eDNA) could be a promising method for ecological surveys in the future, especially with endangered and rare species. eDNA method is a powerful tool for studying ecology, as it does not require direct taxonomic observation, thus allowing information about every organism present in the sample to be obtained, even at a cryptic level. Environmental DNA (eDNA) method has become an important tool for monitoring the latent emergence of species that can be difficult to find, such as invasive species in the early stages of their arrival and expansion, or after control or eradication efforts. Until recently, there have not been many studies employing the eDNA method for the detection of invasive alien species. I hereby conducted an assessment in Jeju Island, South Korea, for detection of invasive alien turtles using the eDNA method. The study was conducted at Yeonhwaji pond in the year 2021. An experiment to check the persistence of freshwater eDNA was examined in a lab setting. The field study was conducted under different weather conditions at a basking site and a non-basking site at different times of day. The result showed that the persistence of eDNA extracted from Pseudemys peninsularis was up to 21 days after removing the genetic source from the collected water sample. A total of 16, 4, and 0 samples were detected positively for Trachemys scripta elegans, Mauremys sinensis and Pseudemys peninsularis species respectively. Samples collected after rain and from non-basking sites showed a negative detection of eDNA. The results from this study demonstrated that eDNA can be applicable for species detection and surveying on Jeju Island, especially with freshwater or endangered species. However, due to the low positive detection rate, the eDNA method cannot replace the traditional methods, as expected. With its unique advantages, eDNA can, however, be combined with traditional methods for faster and more accurate surveys. Besides, this method may be employed to build distribution maps of species and detect endangered or rare species in the wild.

목차 (Table of Contents)

• I. INTRODUCTION 1
• 1. General introduction 1
• 1.1 Invasive species 1
• 1.2 Reptile invasion 2
• 1.3 Freshwater turtles 3
• 2. Ecology and introduction of target species in Jeju Island 5
• 2.1 Trachemys scipta elegans 5
• 2.2 Pseudemys peninsularis 6
• 2.3 Mauremys sinensis 7
• 3. Environmental DNA (eDNA) 8
• 4. Study purposes 10
• II. MATERIALS AND METHOD 12
• 1. Sample collection 12
• 1.1 Preliminary survey for housed laboratory individuals of Pseudemys peninsularis 12
• 1.2 Study site 13
• 1.3 Visual observation 15
• 1.4 Pond sampling 15
• 1.5 Abiotic factors measurement 16
• 2. Filtration 17
• 3. DNA extraction 18
• 4. Polymerase Chain Reaction (PCR) detection 20
• 5. Statistical analysis 21
• III. RESULTS 22
• 1. Preliminary survey for housed laboratory individuals of Pseudemys peninsularis 22
• 2. Biotic factors 23
• 3. Abiotic factors 25
• 4. Environmental DNA detection 27
• 4.1 Detection of Trachemys scripta elegans 32
• 4.2 Detection of Mauremys sinensis 35
• 4.3 eDNA and visual encounter survey 38
• IV. DISCUSSION 39
• 1. Preliminary survey for housed laboratory individuals of Pseudemys peninsularis 39
• 2. Environmental DNA detection 41
• 2.1 Detection of Trachemys scipta elegans 41
• 2.2 Detection of Mauremys sinensis 43
• 2.3 eDNA and visual encounter survey 43
• 3. Recommendations for further studies 44
• V. CONCLUSION 46
• REFERENCES 48