Drought effects on the colonization of benthic macroinvertebrate communities in the early successional phases in experimental mesocosm wetlands

We investigated the drought effects on the colonization rate and pattern of benthic macroinvertebrate communities in newly created mesocosm wetlands in the central Korean Peninsula, from June 2011 to June 2013. The comparison was made between the initial colonization after mesocosm construction (pre-drought) and the recolonization after a drought event (post-drought) with a drought period of 50 days between them. In addition, we categorized communities according to their biological traits in relation to drought. Our results showed that aquatic vegetation abundance and covering degree were higher in post-drought than in pre-drought, thereby influencing rapid colonization. Drought-resistant benthic macroinvertebrates colonized rapidly in post-drought; consequently, the colonization speed was 2.5-fold higher in post-drought than in pre-drought. We classified the benthic macroinvertebrate taxa into three groups: (1) a resistant group which generally emerged after the initial colonization period (e.g., Mollusca, Turbellaria, and Oligochaeta); (2) a sensitive group with diverse life history strategies and biological traits such as active migration or population decline after drought disturbance (e.g., Diptera: Chironominae, Odonata: Orthetrum, Coleoptera: Agabus and Rhantus); and (3) a seasonal group, which emerged only during certain periods and were not markedly influenced by drought (e.g., Ephemeroptera: Cloeon, Diptera: Culicidae, Odonata: Zygoptera and Pantala). Our findings elucidated the effects of drought on benthic macroinvertebrate communities in wetlands by using a mesocosm experiment.