Mapping a super-invader in a biodiversity hotspot, an eDNA-based success story. (July 2021)

• Record Type: Journal Article
• Authors: Baudry, Thomas; Mauvisseau, Quentin; Goût, Jean-Pierre; Arqué, Alexandre; Delaunay, Carine; Smith-Ravin, Juliette; Sweet, Michael; Grandjean, Frédéric
• Is Part Of: Ecological indicators. Volume 126(2021)
• Publication Date: 2021-07
• Subjects: Biodiversity hotspot -- Cherax quadricarinatus -- Environmental DNA -- Freshwater -- Invasive species -- qPCR; Environmental monitoring -- Periodicals; Environmental management -- Periodicals; Environmental impact analysis -- Periodicals; Environmental risk assessment -- Periodicals; Sustainable development -- Periodicals; 333.71405
• DOI: 10.1016/j.ecolind.2021.107637
• Languages: English
• ISSNs: 1470-160X

Abstract

Graphical abstract: Highlights: Development and validation of an eDNA protocol to detect C. quadricarinatus. Evaluation of eDNA persistence in tropical freshwater. Effects of crayfish biomass on eDNA detection probability and efficiency. Identification of key environmental variables affecting detection probability. Updates of C. quadricarinatus presence Martinique freshwater systems. Abstract: The lesser Antilles archipelago in the Caribbean is known as a biodiversity hotspot, hosting many endemic species. However, recent introduction of a highly invasive species, the Australian redclaw crayfish ( Cherax quadricarinatus ), has led to significant threats to this fragile ecosystem. Here we developed, validated, and optimized a species-specific eDNA-based detection protocol targeting the 16S region of the mitochondrial gene of C. quadricarinatus . Our aim was to assess the crayfish distribution across Martinique Island. Our developed assay was species-specific and showed high sensitivity in laboratory, mesocosm and field conditions. A significant and positive correlation was found between species biomass, detection probability and efficiency through mesocosm experiments. Moreover, we found eDNA persisted up to 23 days in tropical freshwaters. We investigated a total of 83 locations, spread over 53 rivers and two closed water basins using our novel eDNA assay and traditional trapping, the latter, undertaken to confirm the reliability of the molecular-based detection method. Overall, we detected C. quadricarinatus at 47 locations using eDNA and 28 using traditional trapping, all positive trapping sites were positive for eDNA. We found that eDNA-based monitoring was less time-consuming and less influenced by the crayfishes often patchy distributions, proving a more reliable tool for future large-scale surveys. The clear threat and worrying distribution of this invasive species is particularly alarming as the archipelago belongs to one of the 25 identified biodiversity hotspots on Earth.