Metabarcoding reveals significant differences in communities with and without invasive seaweeds

While the data corresponding to the 2015 collecting trips are being analysed, we would like to share the first results concerning the communities sampled with and without invasive algae. In the Cíes Island, we compared the photophilous community with Cystoseira nodicaulis (natural assemblage) with equivalent communities with the introduced Asparagopsis armata. In Cabrera, we sampled in the same walls photophilous natural assemblages as well as communities dominated by Lophocladia lallemandii, while at deeper waters we sampled the natural sciaphilous community and Caulerpa cylindracea-dominated patches.

We identified with the gene 18S 2937 MOTUs in these communities. Our statistical analyses showed clear qualitative and quantitative differences between assemblages with and without the invasive seaweeds. While this was expected for the bigger size fractions, even for the smallest fraction (i.e., organisms between 1 mm and 65 microns) the differences were significant. This rich component of the biodiversity cannot be efficiently assessed with conventional methods, while genetic techniques have allowed its quantification and analysis.

Thus, metabarcoding revealed community shifts affecting even the small-sized meio-organisms (animals, algae, and protists) at very reduced spatial scales (tens of meters). The presence of invasive algae has therefore profound effects in community structure at all levels. This is one of the several interesting outcomes we are finding with our data, more soon!

This spatial representation (Multidimensional Scaling) allows the visualization of the differences between the sampled communities linked to the presence of invasive seaweeds

The methods developed in METABARPARK explained in an international book chapter

Owen Wangensteen and Xavier Turon have been invited to write a chapter in the book "Marine Animal Forests. The Ecology of Benthic Biodiversity Hotspots", of the Springer International Publishing Company (ISBN: 978-3-319-17001-5), which is edited by Sergio Rossi, Lorenzo Bramanti, Andrea Gori and Covadonga Orejas.

In this chapter, entitled "Metabardoding techniques for assessing biodiversity of marine animal forests", Owen and Xavier explain the methods developed in METABARPARK to work with hard bottom communities using metabarcoding. We believe that it is crucial to setup standardized protocols, and that this book can be an excellent platform to share and disseminate our experience with the different steps of the metabarcoding process. 

This chapter has been sent out for editorial process, and we foresee that it will be published in the forthcoming months.

Techniques developed in METABARPARK, such as the size fractionation of the samples, can be adopted by other teams working on metabarcoding of marine benthos

METABARPARK at the workshop “Application of genomic tools for benthic monitoring”

The 4-5 April 2016, the Natural History Museum of Geneva (Switzerland) hosted the workshop “application of genomic tools for benthic monitoring of marine environment: from technology to legal and socio-economic aspects”, organised by Prof. Jan Pawlowski of the University of Geneva (http://goo.gl/forms/V9bLHtyJBk).

The workshop was intended as a forum for the exchange of ideas about the potential of environmental DNA (eDNA)-related techniques for assessing biodiversity and the impact of human activities on it. It was attended by environmental professionals, members of regulating bodies, and scientists.

The presentations and discussion were very lively, and the overarching idea is that DNA-derived indicators may be effectively used in the field of environmental monitoring (as they are in other applied sciences). However, more development and standardization is necessary before they can be integrated with- or substitute altogether- current techniques using morphology-based indicators, which are slow, time-consuming, and reliant on a worlwide dwindling taxonomic expertise.

Xavier Turon and Owen Wangensteen contributed to the workshop with the talk “Issues in metabarcoding of marine benthos”, where they pinpointed some conflicting issues, such as the use of DNA vs RNA, the choice between 18S rDNA or COI markers, or the use of a fixed vs a variable threshold for clustering sequences into MOTUs. The talk was illustrated with results obtained in the project METABARPARK.

Xavier Turon and Tom Wilding, of the Scottish Association for Marine Science, at the entrance of the Natural History Museum, with a lovely pet!