Complex relations between freshwater macro- and meiobenthos: interactions between Chironomus riparius and Chydorus piger

• 1 The potential importance of interactions between macro- and meiobenthos in the littoral zone of takes was studied in a series of laboratory experiments with a chironomid and a chydorid.
• 2 In a situation of intraspecific density dependence, Chydorus piger Sars inhibited the growth of Chironomus riparius Meigen, while both second- and fourth-instar C, riparius stimulated the parthenogenetic reproduction of C. piger.
• 3 The meiofaunal chydorids may thus have a structuring effect on macrofaunal chironomid populations by interfering with the early-instar larvae.
• 4 With macro- and meiofaunal species both operating at the primary consumer-level of the food web, this kind of complex interaction will affect the magnitude of secondary production available to higher trophic levels.