Contrasting seasonal and spatial distribution of native and invasive Codium seaweed revealed by targeting species‐specific eDNA

Abstract

Aim Codium fragile , an invasive seaweed, has spread widely during the last century, impacting on local seaweed communities through competition and disturbance. Early detection of C. fragile can help on its control and management. Environmental DNA (eDNA) has proved successful for early detection of aquatic invasive species but its potential use for seaweed remains understudied. We used a species‐specific eDNA qPCR approach to investigate the spatial distribution, abundance, and coexistence of the invasive C. fragile and three native Codium species ( Codium vermilara , Codium tomentosum , and Codium decorticatum ) in the Cantabrian Sea. Location Bay of Biscay, Northern Atlantic Coast of the Iberian Peninsula; two ports, a beach and a rocky cliff. Methods We designed species‐specific primers in barcoding regions targeting short fragments of the rbcL gene for the invasive Codium species, and the elongation factor Tu (tufA) gene for the native species, to assess their spatial and seasonal distributions using quantitative real‐time PCR in samples collected during summer, autumn, and winter. Results We found seasonal differences in the presence of the invasive Codium fragile and two of the native Codium species, but did not detect C. decorticatum at any point. Species distribution patterns produced with qPCR targeting species‐specific eDNA coincided with the known distribution based on previous conventional sampling, with a seasonal alternance of C. fragile and C. vermilara , and a marked dominance of invasive C. fragile in ports, which are known hotspots for invasive species. Main conclusions Our results demonstrate the utility of using eDNA for early detection and monitoring of invasive seaweed. Native and invasive Codium spp. displayed significant seasonal and spatial differentiation that needs to be taken into account in risk management. Regular monitoring of ports and adjacent areas using eDNA should help to assess the potential expansion of invasive Codium and the need for management interventions to avoid the displacement of native seaweed.

Domesticated Populations of Codium tomentosum Display Lipid Extracts with Lower Seasonal Shifts than Conspecifics from the Wild—Relevance for Biotechnological Applications of this Green Seaweed

“…In general, marine organisms exhibit a high plasticity to environmental changes in order to optimize their metabolism and compensate to seasonal variations in their home habitats [9,15,26]. In the present study, spring samples from wild populations presented a lower total amount of lipids than early-autumn samples, but these seasonal differences were not recorded in cultured macroalgae.…”

Life in a drop: Sampling environmental DNA for marine fishery management and ecosystem monitoring

“…Relative abundance of two parasite species on salmon farms [66] Monitoring deep water species Relative abundances of Subarctic, deep water fish species from the continental slope off Southwest Greenland [62] Invasive species abundance Temporal abundance of invasive Codium seaweed in the Bay of Biscay [67] Stock assessment Biomass estimation of Atlantic cod in oceanic waters around the Faroe Islands [29] Applications of using eDNA to assess abundance in the aquatic environment are at present most advanced in freshwater [62]. Abundance estimation using traditional methods such as gillnet data and trawling provides a relative index assumed to be directly proportional to density/absolute abundance [29,64,68].…”

Re-Establishment Techniques and Transplantations of Charophytes to Support Threatened Species

“…In a Canadian investigation, eDNA analyses identified more species belonging to the genera of Potamogeton and Zannichellia than “traditional” methods (Kuzmina et al, 2018 [ 183 ]). Muha et al (2018 [ 184 ]) detected invasive aquatic plants by means of eDNA analysis.…”