Asymmetric interspecific territorial competition over food resources amongst Lake Malawi cichlid fishes

Abstract

The rock-dwelling cichlids in Lake Malawi comprise the most diverse freshwater fish community in the world. Individuals frequently interact with heterospecifics through feeding territoriality. Underwater observations and experiments were conducted to examine interspecific variation in the frequencies of territorial behaviour and its influence on the feeding habits of heterospecifics. Frequencies of chasing and fleeing associated with interspecific territoriality were remarkably different amongst 10 cichlid species. In addition, individual fish that attacked heterospecifics more frequently were attacked less often by them, suggesting that interspecific interactions amongst cichlid species are asymmetric. The experimental removal of territory owners belonging to the most aggressive species resulted in almost fivefold increase in feeding within territories, suggesting that territorial aggression preserves food resources for the territory holder and influences the feeding habits of other species, including those with some dietary dissimilarities. Additional information regarding asymmetric interspecific interactionswould improve understanding about how diverse cichlids within trophic groups manage to coexist.

African Zoology 45(1): 24–31 (April 2010)