The distribution and ecology of littoral Oligochaeta and Aphanoneura (Annelida) of the Natural and Historical Reserve of Isla Martin Garcia, Rio de la Plata River, Argentina

The objective of this paper is to provide data on the distribution and ecology of oligochaetes and aphanoneurans occurring in the Rio de la Plata, Argentina., including details regarding, their densities, faunal characteristics, species richness. diversity and equitability. Between 1995 and 1997. a total of five stations on the Rio de la Plata were sampled on eight different occasions, The taxocenosis of Oligochaeta and Aphanoneura included 30 species belonging in six families: Naididae, Tubificidae, Narapidae, Enchytraeidae. Lumbricidae and Aeolosomatidae. The 2 density varied between 44495 ind m(-2) and 57 ind m(-2). Species richness varied between I and 17, the diversity ranged from 0.07 to 2.55, and equitability varied between 0.08 and 0.64. According to dominance and frequency, the dominant. constant and widely distributed species were: Nais variabilis, Stephensoiana trivandrana, Amphichaeta leydigi, Chaetogaster diastrophus, Limnodrilus hoffmeisteri, Aulodrilus pigueti, Narapa bonettoi and the species of Enchytraeidae and Aeolosomatidae.