Metabarcoding approach for the ballast water surveillance – an advantageous solution or an awkward challenge?

by A. Zaiko et al.

 

R/V “Polarstern"

In this recent collaborative paper, we showcase the performance of metabarcoding approach in comparison to the conventional observations, assessed during the en route experimental ballast water survey onboard R/V “Polarstern”. Ballast waters are considered to be one of the major vectors for human-mediated transport of non-indigenous species (NIS), and therefore contribute to the NIS-related pressures in aquatic ecosystems worldwide. Effective management of ships’ ballast waters is addressed in the Ballast Water Management Convention adopted in 2004 by the International Maritime Organization and implies among other scientific and technical research to be conducted by the Parties. In our study we addressed the applicability of metabarcoding methodology for the biosecurity surveillance, and particularly detection of NIS when still on the pathway (i.e. ships’ ballast waters).

 

Visual analysis of the ballast water samples onboard The combination of traditional visual observations and novel molecular approaches allowed us to follow the dynamics of planktonic communities within ballast tank and provided evidences that despite rather harsh environmental conditions (darkness, low oxygen, temperature fluctuations), there are taxa that manage to survive and even flourish in ballast waters. Such organisms are likely to remain viable upon discharge, thus posing a high risk of incursion to a recipient ecosystem. In our experiment, the metazoan organisms have demonstrated higher persistence than phytoplankton taxa, with most evident drop at the most adverse conditions within the tank (anoxic, high temperature). Protozoans, however, were able to withstand these harsh conditions and even increased in abundance by the end of the 3-week observations. These small organisms are generally underestimated in NIS surveys and inventories, since are easy to overlook and confound in the conventional taxonomic assessment.

Hence, metabarcoding technologies are advantageous being able to detect and identify species from a single cell present in the sample.

The results of this study allowed us to come up with comparative cost-effectiveness analysis of both approaches and suggest some actions for improving the efficacy of ballast water surveillance and management employing next generation molecular technologies.

 Zaiko, A., Martinez, J. L., Schmidt-Petersen, J., Ribicic, D., Samuiloviene, A., & Garcia-Vazquez, E. (2015). Metabarcoding approach for the ballast water surveillance–An advantageous solution or an awkward challenge? Marine pollution bulletin. 

The paper is available in zenodo