Quantitative Evaluation of the Larval Density of Sea Potato Acaudina spp. with Mitochondrial Molecular Marker

The sea potato Acaudina spp. is a species of sea cucumber, belonging to the class Holothuroidea under Phylum Echinodermata. It becomes blooming recently in the East Sea of China, causing serious ecological problems. However, until now there are no molecular data for its larval identification and population genetic analysis. In this study, we firstly screened a mtDNA fragment and demonstrated that it was the species-specific molecular marker for the identification of Acaudina spp. We then developed a quantitative polymerase chain reaction (PCR) method to evaluate the larval density of Acaudina spp. based on this molecular probe. Utilizing this method, we examined 116 plankton samples collected in four seasons from 13 stations along the coastal region in Fujian province, China. The results showed that the high larval density was presented at stations 1, 2, and 3, which were near a quay in the coast. The larval density increased from April and reached the highest value in June and July, suggesting temperature might be the main environmental factor on the effects of its population distribution and density. Our work provides an important molecular tool for species identification and risk evaluation of a potentially invasive species.