abstract
Wrack beds of the intertidal kelp Durvillea antarctica (Cham.) Har. on Marion Island (46�' S, 37�'E) sustain large kelp fly populations. Paractora dreuxi mirabilis (Seguy) is a primary decomposer of stranded Durvillea with larvae reaching a biomass of 2 g per kg of decomposing kelp (wet mass). At 10癈 Paractora completes its life cycle in 80-120 days. Egg, larval and pupal stages last 4, 60 and 40 days respectively. Larvae eat 0,5 times their own dry mass in kelp per day. They attain an individual live mass of up to 100 mg. The feeding and burrowing activity of larvae probably enhance microbial decay of beached kelp. Paractora larvae are preyed on by vertebrate insectivores and probably form an important link in nutrient and energy chains in the littoral zone on Marion Island.
