Étude Bioécologique des Oligochètes dans la région saharienne (El Menia)

Abstract

The biodiversity of soil fauna in Saharan oasis ecosystems remains poorly documented. This study focuses on the bio-ecology of Oligochaetes (earthworms) across four agroecological stations in Jenane El Guelta near the old Ksar of El Menia : Palm Grove, Pomegranate, Pepper, and Stream. Sampling was conducted over two seasons Autumn and Winter (2024-2025) to assess seasonal variations. A total of eight species belonging to three families and six genera were identified. Oligochaete density showed marked seasonal fluctuations, with higher abundance in Autumn due to moderate temperatures and favorable moisture levels. Each had distinct physic-chemical Characteristics that influenced species distribution: Palm Grove station: alkaline soil with clay-sandy texture, stable density with a slight decrease in Winter. Pomegranate station: neutral soil, stable density, dominated by Eiseniella tetaedra. Pepper station: alkaline and calcareous soil, decline in Winter linked to reduced organic matter. Stream station: acidic sandy soil with high conductivity, generally low density with a peak in January. Soil properties such as pH, conductivity, organic matter, total limestone, and granulometry strongly influenced the structure of earthworm communities. Autumn was the most active period, while Winter showed an overall decline in abundance.