03776nab a2200361 a 4500 AR-ReUNN 20260702003054.0 260630s2006 ag |||||||||||||||||eng eng Penchaszadeh, Pablo e. 75000 Darrigran, Gustavo Alberto 147407 Congresso Brasileiro de Limnología. Perspectivas da Limnología para o Século 21 147384 Invasive freshwater mytilid Limnoperna fortunei in the Plata Basin - South America - / P. E. Penchaszadeh, G. Darrigran 2006 1 páginas Disponible en estante de INICNE The invasion of the Southeast Asian mussel Limnoperna fortunei was first reported in the Americas at Río de la Plata, Argentina, in 1991. In 1993 this bivalve, developed population densities of more than 100.000 individuals per sq.m, and entered the Paraná River. Since 1991, it has colonized 1,100 km through the Plata basin. Among the problems associated with the presence of this fouling animal, it has been demonstrated that the community is rapidly changing, i.e. the number of invertebrate species (mainly Olygochaeta and Hirudinea) is favored by the presence and abundance of the mussel while indigenous mollusks are generally constrained and displaced. Limnoperna fortunei is a dioecious species. Hystological analysis for Río de la Plata populations, proved that sexes differentiate at 5 to 10 mm in shell length and that mature oocytes measure 70-100 microns in diameter. During a two year study, three main spawning processes were recorded, in May-July 1993, April-May 1994 and October 1994. Nevertheless other minor spawning were recorded from October 1993 to February 1994 and from June to October 1994. Oocyte proliferation was continuous and immature oocytes were recorded throughout the year. Temperature must be regarded as the main factor responsible for the variations in the spawning intensity, which is related to the minimum and to the maximum temperatures recorded. Several fish were identified as predating on Limnoperna in the coast of Buenos Aires City. Among them, the Anostomidae Leporinus obtusidens, one of the most abundant in the sportive fishing yields, proved to be the most important predator on the mussel. 60% of Leporinus 20-30 mm in total length contained Limnoperna in their digestive tract; Limnoperna shells constituted the 33.4 % of the totaldry content. ; larger fish shows a 100% of presence of Limnoperna in their digestive tract. As much as 120 beacks containing the umbo region (60 mussels) were couned for an individual fish. Small mussels (1.5-5.7mm in shell length) are frequently found unbroken and appear as not bieng digested. The presence on Limnperna forturnei in the Paraná-Río de la Plata basin, with its extraordinary secondary production, occupying an empty ecological niche in this environment, has introduced a new item in the diet of some fish and constitute the principal food for Leporinus obtusidens. As this fish lives in all the basin, in current waters as in pounds, and it is a species wth high marketable value, that adapts extraordinarily to captivity conditions, it could be used as a control for the mussel Limnoperna fortunei in affected enclosed systems. Peces de Agua Dulce 6471 Leporinus Obtusidens 119208 Boga 119194 Alimentos 545 Moluscos 8454 Limnoperna Fortunei 136672 Rio de la Plata 7617 Rio Parana 10033 Argentina 4258 Freshwater Fish 117439 Inland Waters 117440 Feeding 121704 ART (INICN)33600 234584 234584 234584 AR-ReUNN spa AR-ReUNN aacr2