Pessotto M A, Nogueira M G
Departamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista - UNESP, Rua Prof. Dr. Antonio Celso Wagner Zanin, s/n, CEP 18618-689, Botucatu, SP, Brazil.
Braz J Biol. 2018 Nov;78(4):773-784. doi: 10.1590/1519-6984.180789. Epub 2018 Jan 15.
The golden mussel, Limnoperna fortunei, is an Asian freshwater bivalve introduced in South America in the beginning of the 1990's, probably through ballast water releases in La Plata River estuary. It dispersed north through Paraná, Uruguay and Paraguay Rivers. The study evaluated the macroscale (18° to 34° S; 45° to 60° W) distribution of L. fortunei (larval stages) in the main rivers and reservoirs of La Plata Basin. Samplings were performed through 68 µm vertical plankton net hauls. Limnological variables were simultaneously determined. Larvae abundance correlated significantly with oxygen (positively) in summer, with temperature (positively) in winter and with total phosphorus and total nitrogen (both negatively) in winter. We expected densities to decrease towards north (latitudinal gradient) and increase in lentic conditions (reservoirs). Despite maximum density was found near the introduction point (La Plata River) similar value was also observed 2,000 km north (Paraguay River). The first hypothesis was refuted. The second hypothesis was partially accepted. Abundances were consistently higher in summer. Higher trophic conditions and fast flow seem to inhibit population growth. Food resources (chlorophyll a) locally influenced temporal variation. Limnoperna fortunei is widely distributed in La Plata basin, reaching high larval densities superior to 10,000 ind. m-3, in all major sub-basins. The species exhibits a high intrinsic dispersal ability (free planktonic larvae), wide tolerance to environmental factors and dispersion is potentialized by natural dispersion processes (e.g. fauna displacement) and human facilitation (e.g. commercial navigation).
金贻贝（Limnoperna fortunei）是一种亚洲淡水双壳贝类，于20世纪90年代初被引入南美洲，可能是通过拉普拉塔河河口的压舱水排放。它通过巴拉那河、乌拉圭河和巴拉圭河向北扩散。该研究评估了拉普拉塔河流域主要河流和水库中金贻贝（幼体阶段）在宏观尺度（南纬18°至34°；西经45°至60°）的分布情况。通过68微米垂直浮游生物网拖网进行采样。同时测定了湖泊学变量。夏季幼体丰度与氧气（呈正相关）、冬季与温度（呈正相关）以及冬季与总磷和总氮（均呈负相关）显著相关。我们预计密度会向北（纬度梯度）降低，在静水条件（水库）下增加。尽管在引入点（拉普拉塔河）附近发现了最大密度，但在向北2000公里处（巴拉圭河）也观察到了类似的值。第一个假设被推翻。第二个假设部分被接受。夏季的丰度一直较高。较高的营养条件和快速水流似乎会抑制种群增长。食物资源（叶绿素a）局部影响时间变化。金贻贝在拉普拉塔河流域广泛分布，在所有主要子流域中，幼体密度高达10000个/立方米以上。该物种具有很高的内在扩散能力（自由浮游幼体），对环境因素具有广泛的耐受性，并且自然扩散过程（如动物迁移）和人类促进因素（如商业航行）会增强其扩散能力。
