Aquatic macroinvertebrates associated with Salvinia molesta according to developmental stage in two tropical lagoons (Ono and Hébé, Côte d’Ivoire)

This study investigated macroinvertebrate communities associated with different growth stages of Salvinia molesta in Ono and Hébé lagoons by describing their structure and functional traits, and examining how environmental factors influence faunal composition. Monthly samples were collected using a dip net, and key abiotic parameters were recorded. Although environmental variables varied between lagoons, pH remained stable. A total of 144 taxa belonging to 49 families, 13 orders, and five classes were identified, including 77 in Ono and 101 in Hébé. The reduced diversity in Ono is strongly linked to local anthropogenic disturbances. In both lagoons, taxon richness increased from juvenile to adult fern stages, with Insects, especially Coleoptera, Odonata, Heteroptera, and Diptera, dominating the communities. The highest values of rarefied richness, Shannon-Weaver index, and density appeared at the adult stage, indicating greater structural complexity. Predators constituted the main trophic group, while harmful taxa were approximately twice as abundant in adult stands. Conductivity, pH, dissolved oxygen, temperature, transparency, nitrate, and phosphorus were the main drivers of macroinvertebrate distribution. Sensitive indicator taxa (Ephemeroptera and Trichoptera) were more abundant and consistently recorded in Hébé, unlike in Ono, further highlighting the negative impact of anthropogenic pressures on this lagoon.