February 1st to 5th 2016
Olhão, Portugal
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Developing molecular tools for early detections of invasive species: the case of the zebra mussel Dreissena polymorpha in the Baltic Sea.

Scientific Exhibition
Biological Invasions
Thursday, February 4, 2016 -
17:30 to 19:30

Ardura, A. 1 Zaiko, A. 2 Borrell, Y.J. 3 Samulioviene, A. 4 García-Vázquez, E. 5

1USR3278-CRIOBE-CNRS-EPHE. Laboratoire d'excellence "CORAIL". Université de Perpignan-CBETM. 58 Rue Paul Alduy. 66860-Perpignan CEDEX, France
2Coastal and Freshwater Group, Cawthron Institute, 98 Halifax Street East, 7010 Nelson, New Zealand
3University of Oviedo, Spain
4Marine Science and Technology Centre, Klaipeda University. H. Manto 84, LT 92294, Klaipeda, Lithuania
5University of Oviedo, Spain

The zebra mussel Dreissena polymorpha is one of the worst invasive species in the world. It is a benthic bivalve with dispersive planktonic larvae native to the drainage basins of the Black, Caspian and Aral Seas in Eastern Europe and Western Asia. Originating from the harsh environments of the Caspian Sea, the mussel has evolved to be robust against diverse conditions. In the 30 years since zebra mussels first appeared in North America, they have become one of the most widespread and abundant freshwater animals, and have fundamentally transformed freshwater food webs and biogeochemistry. A problem for early detection of Dreissena by conventional methodology is that, in general, larvae of benthic species are not identified in traditional zooplankton surveys due to their cryptic morphology and lack of sufficient specific taxonomical expertise. This implies potential biosecurity risks, since many invasive sessile organisms have a dispersive planktonic stage, like Dreissena, that might be overlooked in morphologically analyzed samples. It means that these and other non-indigenous species can spread unnoticeably in the region until their presence and impacts become apparent and irreversible. Since the traditional sampling tools seem to be insufficient to detect NIS in aquatic environments when organisms are not apparent, alternative approaches are being investigated in the last decade. Several studies demonstrate the efficacy of environmental DNA (eDNA) coupled with Next-Generation Sequencing of informative regions such as 16S rRNA and Cytochrome oxidase I gene (COI) as a tool for eukaryote species detection in aquatic environments. Species-specific molecular markers can be PCR-amplified from eDNA, allowing to detecting the presences of organisms of interest such as pests from early invasion fronts. The objective of the present study was to develop and test species-specific molecular markers for early detection of the dangerous zebra mussel D. polymorpha from environmental samples. We have designed new species-specific primers, evaluated their sensitivity in vitro and from field DNA samples, and compared gel and capillary electrophoresis for visualization of the PCR products. NGS Metabarcoding (PCR amplification and massive sequencing of a DNA Barcode) was used as an independent method for quantifying Dreissena DNA molecules in natural environmental samples. Such environmental samples were taken from two different environments within the Baltic Sea with different densities of Dreissena: the River Odra Estuary (Szczecin Lagoon) in Poland, highly invaded by this species, and the Klaipeda coast (Lithuania) where Dreissena is also present but the density is much lower in comparison with the Odra lagoon.

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