Rio de la Plata Basin: a home for non-native freshwater polychaetes

Abstract

Introductions of non-native species threaten global biodiversity, particularly in freshwater ecosystems. Ballast water from ships is a significant pathway for them, impacting regions like the La Plata River basin. This study documents the newly reported presence of the invasive brackish/freshwater sabellid polychaetes Laonome xeprovala in the Paraná River. The Paraná River, South America’s second-largest river, features a primary channel and numerous secondary channels, with about 40% of its floodplain comprising lakes. This study examines benthic invertebrates through sediment sampling across 17 sites in the Middle Paraná River. Morphological and DNA analyses were used to identify sabellids. This study confirms the presence of Laonome xeprovala in the Middle Paraná River, with density ranging from 44 to 578 ind/m2 across six sampling sites. Environmental conditions, including temperature, pH, and conductivity, varied, highlighting the specie’s adaptability to different habitats. Laonome xeprovala, a polychaete species associated with brackish and freshwater environments, has been identified as invasive in Europe and documented in various aquatic systems, likely facilitated by shipping activities. Recent genetic and morphological analysis indicates its presence in the Paraná River, raising questions about its native status and potential impacts on local ecosystems. Although it still represents a relatively small proportion of the community, its adaptability indicates that it could inhabit a broader range of environments, which could threaten native biodiversity. Laonome xeprovala has the potential to disrupt native communities, leading to a decline in benthic diversity and the ecological benefits provided by the Paraná River, which calls for additional research and strict measures to prevent further introductions.