Chironomids (Diptera: Chironomidae) from three temporary ponds of different wet phase duration in Central Italy

A one year-study on three temporary ponds in Central Italy examined relationships between the composition and structure of chironomid communities and some environmental variables. The three ponds showed differences in wet phase duration, dissolved oxygen content, and sediment organic matter. In the pond with longer aquatic phase and lower oxygen content a dominance of Chironominae (mainly Chironomus thummi gr. and C. plumosus gr.) and Tanypodinae (mainly Psectrotanypus varius) was recorded, whereas in the pool with shorter habitat duration and higher oxygen content, Orthocladiinae [mainly Psectrocladius (Allopsectrocladius) spp. and Cricotopus sylvestris] were dominant. The pond with an intermediate wet phase length showed some characteristics common to the other two ponds. The preferences of chironomids for ponds of different habitat duration can probably be ascribed to their larval size and strategies to survive in ephemeral waters. A more detailed analysis of chironomids of the pond with longer wet phase showed the existence of three major phases of pond life (filling, intermediate and drying phases), according to the seasonal variations and the physicochemical conditions.