Molecular Detection of Baltic Prawn (Palaemon adspersus) during Larval Release
Abstract
Marine decapods are one of the largest groups of invasive species in marine and coastalenvironments. They have a significant ecological and economic impact in the nativeenvironments. Due to their body structure (hard exoskeleton), they release less DNA in theenvironment, which makes it difficult to detect. In light of this, a study was conducted using theeDNA method to identify a hard-shelled marine decapod that is common in Norway. Theprimary aim was to develop a species-specific and highly sensitive assay to detect Palaemonadspersus on the coast of Agder, Norway. Using a newly designed Taqman probe andspecies-specific primers, the eDNA was run through qPCR. Higher sensitivity was demonstratedby gDNA serial dilution, and the method's specificity was demonstrated by an in silico test thatcompared the designed primers and probe with closely related marine decapod species. To findout the effectiveness of the eDNA method, the findings were compared with a traditionalapproach, visual inspection. Only 3 of the 16 zooplankton samples contained Baltic prawnlarvae, whereas 13 of the 20 samples had positive eDNA detection for the Baltic prawn. In manyways, the results of the eDNA method were superior to the visual inspection.
The lunar phase, tides, day-night cycles, currents, and other variables all affect the synchronizedlarval release pattern in marine decapods. The aim of the study also includes finding out thelarval release pattern of Palaemon adspersus and possible improvement of detection in theeDNA method. The zooplankton sampling and microscopic analysis did not find any clearpattern of larval release. It is difficult to distinguish between life stages, determine the larvalperiods, and determine the abundance of species using the eDNA method; in these ways, visualinspection can be an efficient method. But the eDNA method successfully detects Palaemonadspersus not only in the possible larval release season but also in November. The successfuldetection of this species indicates that the method is effective enough to detect local marinedecapods for conservation purposes and other marine invasive decpods for early eradication andmanagement, despite the fact that factors such as hard-shelled body structures hinder the releaseand concentration of DNA in marine environments.