Automated classification in turtles genus Malayemys using ensemble multiview image based on improved YOLOv8 with CNN.

In Thailand, two snail-eating turtle species in the genus Malayemes (M. subtrijuga and M. macrocephala) are protected animals in which smuggling and trading are illegal. Recently, a new species M. khoratensis has been reported and it has not yet been considered as protected animal species. To enforce the law, species identification of Malayemes is crucial. However, it is quite challenging and requires expertise. Therefore, a simple tool, such as image analysis, to differentiate these three snail-eating species would be highly useful. This study proposes a novel ensemble multiview image processing approach for the automated classification of three turtle species in the genus Malayemys. The original YOLOv8 architecture was improved by utilizing a convolutional neural network (CNN) to overcome the limitations of traditional identification methods. This model captures unique morphological features by analyzing Malayemys species images from various angles, addressing challenges such as occlusion and appearance variations. The ensemble multiview strategy significantly increases the YOLOv8 classification accuracy using a comprehensive dataset, achieving an average mean average precision (mAP) of 98% for the genus Malayemys compared with the nonensemble multiview and single-view strategies. The species identification accuracy of the proposed models was validated by comparing genetic methods using mitochondrial DNA with morphological characteristics. Even though the morphological characteristics of these three species are ambiguous, the mitochondrial DNA sequences are quite distinct. Therefore, this alternative tool should be used to increase confidence in field identification. In summary, the contribution of this study not only marks a significant advancement in computational biology but also supports wildlife and turtle conservation efforts by enabling rapid, accurate species identification.

Effects of blood mercury accumulation on DNA methylation levels in the Khorat snail-eating turtle (Malayemys khoratensis).

Mercury (Hg) has adverse effects on humans and wildlife. Hg exposure can cause significant alterations in DNA methylation, an epigenetic modification that causes various illnesses. Hg accumulation in the blood of the Khorat snail-eating turtle (Malayemys khoratensis) from northeastern Thailand was previously reported. Thus, this study aimed to assess total mercury (THg) levels in M. khoratensis blood and to examine the impact of these concentrations on DNA methylation (5-methylcytosine, 5-mC) levels. We divided turtles based on morphological characteristics into two groups, normal and deformed, and then the levels of each variable in both groups were assessed. The deformed group presented higher mean THg concentration and DNA methylation levels compared to the normal group; however, the differences were not significant. Additionally, we found no correlation between DNA methylation levels and THg concentrations in both groups. This study is the first attempt to investigate the relationship between mercury accumulation and DNA methylation in the blood of deformed freshwater turtles.

Parasitism of Placobdelloides siamensis (Oka, 1917) (Glossiphoniidae: Hirudinea) in Snail-eating Turtles, Malayemys spp., and the effects of host and aquatic environmental factors.

The Siam Shield Leech, Placobdelloides siamensis, is a common leech found on Malayemys turtles in Thailand. Sixty Snail-eating Turtles (29 Malayemys macrocephala and 31 M. subtrijuga) were caught over twelve months (February 2017 - January 2018) to determine host characteristics (body size, weight and sex), parasitism (prevalence, intensity and density) and seasonal aquatic environmental factors (conductivity, nitrate nitrogen, dissolved oxygen, pH, salinity and total dissolved solids). There was no significant difference of infection rate between species and sex in both turtle species. Leech prevalence indicated that all turtle individuals were infected throughout year, while the infection rate was significantly higher in larger and heavier turtles mainly on the carapace with an average number of leech approximately 474.80 ± 331.38 individuals for individual host infection and 76.53 ± 20.27 individuals for infection per 100 g body weight. The high level of leech parasitism also caused a rot wound and shell hole which caused the host to die. Aquatic environmental factors did not influence the infection of leeches in both turtle species. Therefore, the factors that influenced the infection rate of P. siamensis were based on only host body size and weight without effect from season. In addition, this study also showed two new hosts, including Cyclemys oldhamii and Heosemys grandis and the widespread distribution from northern, north-eastern, western, central and southern Thailand were reported.