Inés Ezcurra de Drago

Tolerance to desiccation of an invasive mussel, Limnoperna fortunei (Dunker, 1857) (Bivalvia, Mytilidae), under experimental conditions

Limnoperna fortunei (Dunker, 1857) (Bivalvia, Mytilidae) was first reported from Río de La Plata in 1991; soon thereafter, it spread widely throughout the basin, causing great damage to all sorts of water supply systems. The desiccation period that young and adults can tolerate was analyzed in laboratory and outdoor experiments. L. fortunei is tolerant to desiccation. The tolerance increases with size. About 72 h was required to kill small mussels (up to 6 mm), 192 h to kill medium-sized adults (>6–15 mm) and 276 h to kill maximum-sized mussels adults (>15–27 mm) in laboratory exposures, and 72 h, 96 h and 108 to kill small, medium-sized and maximum sized mussels in outdoor exposures. The results have implications for using desiccation to combat the spread of L. fortunei.

Invasion process of Limnoperna fortunei (Bivalvia: Mytilidae): the case of Uruguay River and emissaries of the Esteros del Iberá Wetland, Argentina

Limnoperna fortunei (Dunker, 1857), during its invasion process in South America, has caused severe impacts both on natural environments altering native biodiversity, ecosystem structure and function-, and on man-made structures causing economic looses. Twenty-one samples were taken from the right bank of the Uruguay River, from tributaries of the Uruguay and Parana Rivers, the drainage of the Esteros del Ibera Wetland. Based on this fieldwork, the presence of larvae and adults of L. fortunei was determined. Also, through the comparison of environmental characteristic with the known tolerance limits for the species, the possibility of its establishment in environments not yet invaded was determined. Most of the sampling stations have features that allow the development of stable populations L. fortunei, including the rivers that drain the Esteros del Ibera, allowing access of this invasive species to this important wetland.

Sandy rivers: a review on general ecohydrological patterns of benthic invertebrate assemblages across continents

ABSTRACT The middle and lower sections of most large rivers have fine-grained bed sediments, which may have a strong influence on the functional and taxonomical structure of benthic invertebrates. Based on results from several studies by the authors on the faunal assemblages and habitat structures of the Paraguay–Paraná River system (Brazil, Paraguay, Argentina), from European (Rhine, Loire) River systems, and data from the literature, this review identifies general patterns which appear to have a global character. On one hand, the invertebrate assemblages largely differed between the main channel (MC) and the corresponding floodplain habitats in different sections, and also the floodplain habitats along the river channel revealed great differences in their biodiversity. On the other hand, there was a remarkable homogeneity among the main-channel sections within and even between river systems. We consider physical habitat features as the crucial variables responsible for these patterns. In cross-sections from the MC towards the floodplain habitats, grain size, organic matter content and oxygen supply change dramatically, and different floodplain habitats along the same river system may have different successional stages even at small geographical distances. The sandy structure of potamal habitats (including underwater dunes), however, provides a set of habitat features characterized by continuously changing sediment structures with well-defined grain sizes, low organic matter contents and good oxygenation, which force a set of adaptations by the invertebrates that limits but stabilizes the diversity of invertebrates in these large river sections. A better understanding of the ecohydrological interactions between habitat dynamics and benthic invertebrates is needed to improve sustainable river ecosystem management. We discuss the non-recovery of large benthic invertebrate species in the lower section of large rivers after improvement of the water quality in the context of these ecohydrological features. Conclusions are drawn for river restoration.