Density, Recruitment, and Shell Growth of Limnoperna fortunei (Mytilidae), an lnvasive Mussel in Tropical South America

ABSTRACT

Limnoperna fortunei (Dunker, 1857) is an invasive freshwater bivalve native to rivers and streams of China and Southeast Asia. In 2001, it was discovered in Itaipú Reservoir, and its population has grown considerably since then. The aim of this study was to estimate density, recruitment, and individual growth of L. fortunei in a subtropical region from a field experiment using an artificial substrate. Samples were collected between December 2004 and December 2005 at Bela Vista Reservoir in Foz do Iguaçu, Brazil. Mussels were counted and measured to generate size-frequency and distribution data. Maximum and minimum densities (± standard deviation) were 204 ± 17 ind.100 cm⁻² and 94 ± 22 ind.100 cm⁻¹, respectively. Shell length ranged between 1 and 36 mm, and shell length frequency indicated presence of young mussels with variable densities throughout the period surveyed. The von Bertalanffy model fitted successfuHy in all cases explaining more than 96% of the variation in shell length. Measured growth parameters (k = 2.35 year⁻¹, L_∞ = 38 mm) were different from those estimated for populations of L. fortunei in a temperate region.