Invasion by Limnoperna fortunei (Dunker, 1857) (Bivalvia, Mytilidae) of the Pantanal Wetland, Brazil

Abstract

Limnoperna fortunei (Bivalvia, Mitylidae) was introduced into South America in 1991 in the La Plata River (Argentina). It arrived in the ballast water of ships coming from Asia, where this species is native. It was first observed in 1998 in the Paraguay River. Limnoperna was introduced into the Pantanal region as hull fouling of vessels using the Paraguay-Parana waterway. This study describes how L. fortunei came to the Pantanal region, and provides details of its occurrence, density, and impacts. From 1999 to 2002, observations and sampling on natural and artificial substrates in the Paraguay River were made. Some aspects of the spread and impacts, based on local community information, were also analyzed. On artificial substrate the density reached 523.8 individuals m )2 and on natural substrate (rocks), up to 10,000 individuals m )2 were found. The densities observed were quite low compared to those found in Southern Brazil, where values up to 100,000 individuals m )2 have been recorded in the last 3 years. In the Paraguay River, the population density of L. fortunei can be negatively impacted by periodic low levels of dissolved oxygen and decreases in pH to between 5 and 6. Such conditions are frequently present during the periodic flooding or inundation of this area. Under these conditions, a high mortality of L. fortunei was recorded in March of 2002, on both natural and artificial substrates. Despite low densities, L. fortunei can colonize water cooling systems of boats, obstructing water circulation and causing motor overheating. Accumulation in water supply equipment, such as pumps and pipes has also been observed.

More than two decades after the introduction of Limnoperna fortunei (Dunker 1857) in La Plata Basin

“…Interior routes of commercial navigation transporting six millions tons of cargo per year (Silveira, 2005;Oliveira et al, 2004;Oliveira et al, 2011) explain the fast dispersion of L. fortunei along the Paraguay River. The species was found in 1998, near the city of Corumbá (Brazil) (Oliveira et al, 2006), more than 2,000 km far from the introduction area (La Plata estuary).…”

Introdução de Espécies em Ecossistemas Aquáticos: Causas, Prevenção e Medidas de Controle

“…O uso de água de lastro em grandes navios para conferir estabilidade e capacidade de manobra tem sido um meio eficaz de introdução de organismos marinhos e de água doce (OLIVEIRA et al, 2006). Os navios atuais transportam entre 06 e 10 bilhões de toneladas de água de lastro por ano, introduzindo espécies entre os continentes, com um deslocamento diário estimado de 3.000 a 7.000 espécies (SANTOS; LAMONICA, 2008).…”

Structure and density population of the invasive mollusc Limnoperna fortunei associated with Eichhornia crassipes in lakes of the Middle Paraná floodplain

“…Since its introduction in South America in 1991, this mollusc has spread widely in the Río de la Plata Basin, also reaching several other minor watersheds (Mar Chiquita, Guaíba, Tramandaí, and Patos-Mirim (Oliveira et al, 2014). At present its distribution includes Argentina, Uruguay, Paraguay, Bolivia and Brazil (Boltovskoy et al, 2006;Oliveira et al, 2006;Darrigran et al, 2012).…”

“…Indeed, practically all these figures refer to abundances over very restricted areas, usually less than 1 m 2 in size, and the sites in question are not selected at random, either because they are densely covered by mussels, or are ad hoc deployed artificial substrata . Particularly, in the Paraná River, studies on the population densities of L. fortunei are restricted to the lower (Boltovskoy and Cataldo, 1999;Boltovskoy et al, 2006;Darrigran et al, 2007;Sylvester et al, 2007) Oliveira et al, 2006;Belz et al, 2010;Oliveira et al, 2010), with values above 250,000 ind. m -2 .…”