Aquatic Coleoptera and Heteroptera inhabiting waterbodies from Berisso (Buenos Aires province, Argentina).

FERNANDEZ L.A. & M. LOPEZ RUF

REVISTA DE BIOLOGíA TROPICAL

Editorial de la Universidad de Costa Rica

Lugar: San José de Costa Rica; Año: 2006 vol. 54 p. 139 - 148

0034-7744

Abstract Coleoptera and Heteroptera associated with aquatic environments were studied from Berisso, near Río de La Plata estuary (Buenos Aires Province, Argentina). Four waterbodies were characterized and compared: artificial pond, shallow pool, stream and artificial channel. During a period of 12 months, from April 1999 to April 2000, samplings were carried out twice a month, with a round sieve. Samples were quantified using a definite unit of time (one hour/worker), when the floating vegetation was present; also four 25 cm diameter samples were extracted and placed in Berlese-Tullgren funnel for 48 hours.Three abiotic parameters were mesured to characterize the habitat: temperature, pH and conductivity. Specimens were preserved in 70° ethanol, and posteriorly identified. For each sampling station presence frequency (F %) and dominance or relative abundance (D %) was calculated for each species, as well as its richness (S), and diversity (H´). Similarities in taxonomic composition among sampling stations were quantified using Jaccard´s index based on a presence/absence matrix for the insect fauna of each sampling station. A total of 68 species belonging to 8 families of Coleoptera and 11 families of Heteroptera were collected. Both taxocoenosis were characterized and their main ecological features compared (frequency, abundance, species richness and diversity). The highest number of species (41) was registered in the shallow pool, whereas in the stream 34 species were found, 29 in the artificial pond and 25 in the artificial channel. With respect to specific diversity, the highest values were observed during spring in all the sampling stations. The highest frequency of Coleoptera was shown by Helochares talarum and Suphisellus nigrinus ?. While in the Heteroptera it was shown by Lipostemmata humeralis, Lipogomphus lacuniferus and Ranatra segrega. The most abundant species registered were not necessarily the most frequent ones. Taking into account the frequency and relative abundance values, the different populations which comprise the studied communities according to five categories have been classified. Coleoptera constitutes the most important group in species richness. Each environment studied showed a taxocoenosis of Coleoptera and Heteroptera with inherent characteristics.