Density and body size of the larval stages of the invasive golden mussel (Limnoperna fortunei) in two neotropical rivers Densidade e tamanho dos est芍gios larvais do molusco invasor mexilh o dourado (Limnoperna fortunei) em dois rios neotropicais

作者：Vivianne Eilers; Marcia Divina de Oliveira; Kennedy Francis Roche

来源：Acta Limnologica Brasiliensia, 2011.

• larvas planct nicas
• mexilh o dourado
• Limnoperna fortunei
• Pantanal
• especie exotica
• planktonic larvae
• golden mussel
• Limnoperna fortunei
• Pantanal
• exotic species

AIM: The present study involved an analysis of the monthly variations in the population densities and body sizes of the different stages of planktonic larvae of the invasive golden mussel (Limnoperna fortunei), in the rivers Paraguay and Miranda; METHODS: The study was carried out between February 2004 and January 2005. Monthly collection of the plankton samples was accompanied by physical, chemical and biological analyses of the water; RESULTS: The Miranda River presented higher values of calcium, pH, alkalinity, conductivity and total phosphorous. Larval density varied from 0-24 individuals.L-1 in the Paraguay River, with a peak in March of 2004, while in the Miranda River, densities varied between 0-9 individuals.L-1 with a peak in February of 2004. No larvae were encountered during the coldest months, May and June. No significant correlations were found between environmental variables and larval density in either river. Only the valved larval stages were recorded. The %26quot;D%26quot; and veliger forms were most abundant; umbonate larvae were rare in the Miranda River samples. Mean body sizes of %26quot;D%26quot;, veliger and umbonate larval stages were, respectively, 111, 135 and 152 米m, in the Paraguay River, and 112, 134 and 154 米m in the Miranda River. Principal Components Analysis indicated positive relationships between %26quot;D%26quot; larval stage size and the ratio between inorganic and organic suspended solids, while negative relationships were found between larval size and calcium and chlorophyll-; CONCLUSIONS: The larvae were recorded in the plankton during most of the year, with the exception of the two colder months. Neither densities nor larval stage body sizes were significantly different between the two rivers. Possible positive effects of food and calcium concentrations on body size were not recorded. This species may be adapted to grow in environments with elevated sediment concentrations. OBJETIVO: O presente estudo analisou as varia es mensais em densidades populacionais e tamanho dos diferentes est芍gios das larvas planct nicas do molusco invasor mexilh o dourado (Limnoperna fortunei), nos rios Paraguai e Miranda; M谷TODOS: O estudo foi realizado entre fevereiro de 2004 e janeiro de 2005. Amostras mensais de plancton foram acompanhadas pela an芍lise de caracter赤sticas f赤sicas, qu赤micas e biol車gicas da 芍gua; RESULTADOS: O rio Miranda apresentou maiores valores de c芍lcio, pH, alcalinidade, condutividade e f車sforo total. A densidade das larvas variou entre 0-24 indiv赤duos.L-1 no rio Paraguay, com o m芍ximo em mar o de 2004, enquanto no rio Miranda, a densidade variou entre