Several green algae are notoriously difficult to distinguish because of their great morphological variability and/or similarity, which is especially true for the genus Ulva.
DNA barcoding approaches are currently indispensable for their reliable identification. However, such approaches often fail if rare or inapparent species are to be detected in large mixed populations of Ulva species, for example early after species introductions into new habitats.
We therefore developed a detection method based on next generation DNA sequencing, suitable for analysis of DNA traces in conserved water samples or particles enriched by filtration from such samples.
Thus, this method is based on the enrichment of so called environmental DNA (eDNA) which accumulates in the surroundings of the algae and originates from e.g. thallus fragments, spores or cell debris.
Such samples can be analyzed by applying high-throughput sequencing methods – for example metabarcoding – which allow for a rapid monitoring and measurement of biodiversity.
Within our project, we developed a new primer pair that allows for amplification of a 475 bp long section within the plastidic tufA marker gene. We are able to show that the newly developed primers are relative group specific and that the relatively short target amplicon still allows for good differentiation of Ulvales and Ulothrichales at the species level.
Our study and the development of an eDNA approach for green algae biodiversity measurements offers a new method for the early detection of alien- and invasive species and allows for the detection of rare and possibly threatened species. Additionally, this method is especially suitable for comparing the biodiversity of different sites (e.g. strongly frequented harbors with nature reserve areas) or on different time scales (e.g. seasonality).
Do you want to be part of our plan to measure and disentangle the global biodiversity of Ulva sensu lato by providing a water sample? Then contact me.