Resumen de Advances in the use of molecular tools in ecological and biodiversity assessment of aquatic ecosystems

Maria João Feio, Ana Filipa Filipe, Aina Garcia Raventós, Alba Ardura Gutiérrez, Ana Raquel Calapez, Ana María Pujante Mora, Andreia Mortágua, Cesc Múrria Farnós, Daniel Díaz de Quijano, Filipa MS Martins, Sofia Duarte, Marta Sainz Bariáin, Rita Cordeiro, Sinziana F. Rivera, Leif O.S. Väisänen, Amélia Fonseca, Vítor Gonçalves, Eva García Vázquez, David Vieites Rodríguez, Elena A. Ivanova, Filipe Oliveira Costa, José Barquín Ortiz, Verónica Rojo, Joaquín Vierna, Maria Fais, Marcos Suarez, Marko Nieminen, Monica Hammers-Wirtz, Olesia V. Kolmakova, Maria Y. Trusova, Pedro Beja, Raquel González, Serge Planes, Salomé F.P. Almeida

• Conservation and sustainable management of aquatic ecosystems is a priority in environmental programs worldwide. However these aims are highly dependent on the efficiency, accuracy and cost of existent methods for the detection of keystone species and monitoring of biological communities. Rapid advances in eDNA, barcoding and metabarcoding promoted by high-throughput sequencing technologies are generating millions of sequences in a fast way, with a promising cost reduction and overcoming sorne difficulties of the traditional taxonomic approaches. This paper provides an updated broad perspective of the current developments in this dynamic field presented in the special session (SS) "The use of molecular tools in ecological and biodiversity assessment of aquatic ecosystems" of the XIX Congress of the lberian Association of Limnology (AIL20l8), held in Coimbra, Portugal. ' Developments presented are mainly focused on the lberian Península (Portugal and Spain, including Atlantic Macaronesian islands) but include studies in France, Germany, Finland, Russia (Siberia) and South America. The networks within which these researchers are involved are yet even broader, profiting from existing molecular facilities, and traditional taxonomic expertise, which can be viewed as a characteristic ofthis new research area. lt was evident in the SS that the use ofmolecular too Is is widespread, being used to study a diversity of aquatic systems, from rivers' headwaters to estuaries and coastal Iagoons, and volcanic, mountain and frozen lakes to hot springs. The organisms targeted are likewise varied and include fish, macroinvertebrates, meiofauna, microalgae such as diatoms and dinoflagellates, other protists, fungí, and bacteria ( cyanobacteria and other). Sorne studies address the whole biodiversity (i.e., ali species present independently of the taxonomic group) from environmental samples ofwater, biofilms and preservative solution from field samples (e.g., ethanol from macroinvertebrate samples). Great advances were acknowledged in the special session, namely in the use ofmetabarcoding for detecting hidden biodiversity,juvenile stages, low-abundance species, non-indigenous species and toxicity potential, and ultimately for ecological monitoring of diatoms and invertebrates. Yet, severa! drawbacks were highlighted and need further work, which include:

  taxonomic gaps in the reference databases (including gaps at species leve! and on intraspecific variability) or absence of public databases (e.g. for meiofauna), still high sequencing costs, the need of a substantial bioinformatics effort, difficulties in establishing the amount of enviromnental sample necessary for a good DNA extraction and the need for testing different genetic markers to obtain accurate results.