Environmental quality assessment

 

Biological communities are frequently used as indicators of environmental quality in aquatic ecosystems. Governed by international regulatory frameworks like the EU Water Framework Directive (WFD), a wide range of metrics and indices are used to infer environmental status based on the occurrence and abundance of particular taxa. 

Aquatic invertebrates are a key component of this quality assessment, leading to high demand for taxonomic skills, which are in short supply and unlikely to become more widespread. As a result, much of the identification work is carried out by non-expert taxonomists, and error rates are high. A 2010 audit of WFD sample processing found that on average 29% of specimens were overlooked (usually those with smallest body size) and >30% were identified differently by the primary analyst and the auditor. For 16% of samples, this led to differences in final ecological assessment, with the potential to influence the allocation of millions of euros of funding.

Metabarcoding can solve many of these problems, removing reliance on the taxonomic skill level of individuals, ending the bias towards species with large body size, and providing a much greater level of consistency in sample processing. It can also give huge time savings since hundreds of samples can be processed in a matter of days, at a per-sample cost no higher than conventional methods.

In summary, metabarcoding can already provide reliable information on relative environmental quality quickly and cheaply. 

For use in many regulatory contexts such as WFD monitoring, additional work is still needed to either adapt the methodology to provide abundance data (perhaps using a metagenomics approach) or to develop new indices based specifically on the use of metabarcode data. The more interest and early-adoption by end-users, the more quickly these developments will occur. We are always on the look-out for industry partners keen to trial these methods and become part of the exciting movement towards DNA-based environmental quality assessment.