02444naa a2200277 a 450000100080000000500110000800800410001910000230006024501070008326000090019052016530019965000190185265300220187165300190189365300220191265300190193465300240195365300220197765300170199965300210201670000180203770000210205570000190207670000220209577300490211717858422017-03-10 2006 bl --- 0-- u #d1 aOLIVEIRA, M. D. de aInvasion by Limnoperna fortunei (Dunker, 1857) (Bivalvia, Myltilidae) of the Pantanal wetland, Brazil. c2006 aLimnoperna fortunei (Bivalvia, Mitylidae) was introduced into South american 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 descrive how L. fortunei came to the Pantanal region, and provides details of its occrurrence, density, and impacts. From 1999 to 2002, observations and sampling on natural and artificial substrantes 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 indivuals m-² were found. The densities observed were quite low compared to those found in Southern Brazil, where values up to 100,000 indivuals m-² have been recorded in the last 3 years. In the Paraguay River, the population desity 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 naturall 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. aParaguay River aEspécie exótica aExotic species aFreshwater mussel aInvasion route aLimnoperna fortunei aMexilhão dourado aRio Paraguai aRota de invasão1 aTAKEDA, A. M.1 aBARROS, L. F. de1 aBARBOSA, D. S.1 aRESENDE, E. K. de tBiological Invasionsgv. 8, p. 97-104, 2006.