D3345: Diversity of coleopterans and carabid beetles in cattle fields with different water management in the Bajo Delta of the Paraná River, Argentina

Bovine and bubaline livestock is an extensive practice in the Lower Delta of the Paraná River and requires the implementation of improvements for hydrological management. Hydrological management profoundly modifies the characteristics of these wetlands, impacting directly the flora and fauna. Our aim was to compare the abundance of Coleopterans and Carabids in fields with high (HM, polders and dikes) and low (LM, channels) hydrological management. In addition, the richness, diversity and dominance structures of the carabid assemblages were compared. Insect samples were collected in 6 fields (n=3); 10 pitfall traps separated 50 m were placed per field, and remained active for 15 days. Specimens were taken to the laboratory and taxonomically identified. Abundance of coleopterans and carabid did not reveal significant differences (H=0.21,p=0.0644 and H=0.61,p=0.43, respectively) between managements. Rarefaction curves shows that species richness (S) in HM fields (S=19) is higher than LM fields (S=17). Likewise, HM fields diversity (Shannon index, H=2.73) is significantly higher than LM fields (H=2.37; p<0.05). Finally, in LM fields there are three eudominant species (Chlaenius (Chlaenius) oblongus, Pachymorphus striatulus and Tetragonoderus aeneus), while in HM fields, two species were eudominant (P. striatulus and Dailodontus clandestinus). Although richness and diversity were higher in HM fields, the assemblage present is simplified with few dominant and habitat generalist species. All non-dominant species exhibit low abundance. Conversely, LM fields present a more equitable and stable assembly contributing to the ecosystem resilience. Hydrological management directly affects the carabid assemblage in cattle fields in this region.