The Influence of Diplodon chilensis as an Ecosystem Engineer on Benthic Macroinvertebrate Diversity

Diplodon chilensis is one of the most abundant freshwater bivalves in lakes in south-central Chile. Its high filtration capacity and ability to transport organic matter from the water column to the sediment make it an ecologically important species in lakes prone to eutrophication. In situ mesocosm experiments were conducted during seven seasonal campaigns over two years to determine the influence of D. chilensis on benthic macroinvertebrate assemblages. The influence of D. chilensis on benthic macroinvertebrates varied across seasons and sediment quality—Oligochaeta were significantly more abundant in the presence of living mussels during four campaigns. Macroinvertebrate abundance was significantly higher in the treatment with living mussels during the autumn and winter campaigns, and was also positively related to sediment organic matter and total nitrogen. No significant relationships were detected during the spring and summer campaigns. Shannon diversity also showed seasonal variation in its response to mussel presence, whereas Pielou’s evenness remained unchanged. These results highlight the ecological importance of D. chilensis in lentic ecosystems and support its role as an ecosystem engineer whose effects on benthic communities vary seasonally.