Insights into the fauna associated with Egeria densa at the upper section of the international Minho River estuary (NW Iberian Peninsula) 3 decades after its establishment

Abstract

The macrophyte Egeria densa Planchon, 1849 is a freshwater plant native to the subtropical regions of South America. Fast vegetative reproduction and efficient dispersal allow this species to form extensive beds that produce high levels of oxygen in freshwater ecosystems, generating microhabitats that act as refuge and nursery for an array of organisms, increasing sedimentation and light availability. Despite its undisputable ecological role, it is considered invasive and is present on all continents except Antarctica with the first records in Europe occurring at the 20th century. At the international Minho River (NW Iberian Peninsula), the observation of its presence was noted in the 1990s and is now an established population in this ecosystem. This study is the first descriptive-taxonomical assessment of the associated fauna with the exotic macrophyte E. densa, using both morphological and molecular approaches, three decades after its establishment in the international Minho River. Results indicate the presence of a faunal assemblage, composed a total of 20 identified species, including platyhelminths, hydrozoans, bryozoans, molluscs (Gastropoda), annelids (Oligochaeta and Hirudinea), crustaceans (Ostracoda, Copepoda, Branchiopoda and Amphipoda), aquatic mites and insects. Paludicella aff. articulata (Ehrenberg, 1831), Girardia sinensis Chen & Wang, 2015, Lebertia insignis Neuman, 1880 and Ceriodaphnia rigaudi Richard 1894 are recorded for the first time in Portugal.