Sediment development and its influence on the distribution and tube structure of Chironomus plumosus L. (Chironomidae, Diptera) in a new impoundment

Field and laboratory evidence is presented to demonstrate that colonization of a new impoundment by the early invader, Chronomus plumosus L., is strongly influenced by sediment, the depth of which affects both larval abundance and tube shape. Larvae avoid areas with little sediment, such as eroded or newly inundated shores. In laboratory experiments, larvae constructed horizontal tubes in sediments between 3 and 10 mm depth, but in deeper sediments (11–30 mm) most of the larval tubes were vertically orientated. Of these about 70% were U-shaped and the remainder J-shaped. Larval abundance was positively correlated with sediment depth in the range 0–10 mm.