Impact of Flooding on Terrestrial Invertebrate Communities in Flood-Prone Areas of Anambra State, South East Nigeria

Annual flooding events in Anambra State cause significant disruption to terrestrial ecosystems, affecting soil-dwelling and surface-active invertebrate communities. This study investigated the impact of flooding on terrestrial invertebrate diversity and community structure in flood-prone and non-flooded areas within three local government areas of Anambra State. Invertebrate sampling was conducted using pitfall traps, soil corers, and hand collection at paired flooded and non-flooded plots before, during, and after the peak flood period. Collected organisms were identified to the order level and total abundance, taxa richness, and community composition indices were calculated. Results showed a marked reduction in invertebrate abundance and diversity in flooded plots during and immediately following inundation. Anecic earthworm populations collapsed during flooding due to waterlogged soil conditions, recovering only partially within one month of flood recession. Ground-active beetles, ants, and millipedes showed greater resilience and faster recolonisation rates compared to subsurface taxa. Non-flooded control plots maintained stable invertebrate communities throughout the study period. Functional diversity analysis indicated that flooding disproportionately affected detritivore and predator guilds, potentially disrupting nutrient cycling and pest regulation services. The study recommends continued ecological monitoring of flood-prone farmlands and integration of invertebrate conservation considerations into post-flood land rehabilitation programmes in Anambra State. Keywords: terrestrial invertebrates, flooding, community structure, Anambra State, ecosystem services.