Relationships between the spatial distribution of oligochaetes (Annelida, Clitellata) and environmental variables in a temperate ESTUARY SYSTEM OF SOUTH AMERICA (RÍO DE LA PLATA, ARGENTINA)

ARMENDÁRIZ, L.C; RODRIGUES CAPÍTULO, A.; AMBROSIO, E. S.

NEW ZEALAND JOURNAL OF MARINE AND FRESHWATER RESEARCH

RSNZ PUBLISHING

Lugar: otago.ac.nzealand; Año: 2011 vol. 45 p. 263 - 279

0028-8330

The oligochaete assemblage on the Argentine coast ofthe Rı´o de la Plata estuary was sampledseasonally within environments having different types of disturbances. Three habitats weresampled: sediments free of vegetation, sediments within bullrush stands and substrates withLimnoperna fortunei. The species richness, evenness and ShannonWiener diversity values weredifferent among those habitats. The only dominant species (according to the Kownacki index)was Nais variabilis. Mean density values varied between 400 and 199,500 ind./m2. Organicmatter, ammonium and phosphates correlated positively with the mean oligochaete abundance,but not with the granulometry. Physicochemical variables and nutrient levels were measured andtheir relation to the sampling sites assessed through a principal component analysis (41.8%cumulative variance). The canonical correspondence analysis (41.2% cumulative variance)indicated that the oligochaetes distributed along both a eutrophicationpollution gradient and aturbidityconductivity gradient. These results would be useful for assessing the ecological statusofestuaries for a subsequent implementation ofappropriate sustainability-management policies.Keywords: aquatic oligochaete assemblage; large rivers; abiotic affinities; diversity index;dominance; ecological assessment; sustainability