Interspecific competition among anemonefishes: pink anemonefish engage in hostile takeovers of sea anemones occupied by clown anemonefish

Abstract Understanding drivers of species co-existence on coral reefs is important to predict community responses to environmental change. Here, we present, for the first time, observations of takeovers of anemones occupied by one species, Amphiprion percula, by another species, A. perideraion, and ask if habitat characteristics, fish characteristics, or environmental conditions predict these occurrences. Comparing survey data from multiple years, we find that takeovers occur at a frequency of 0.48–6.84 per 100 groups/year and that this does not depend on disturbances (anemone bleaching) in the population. Takeovers are not predicted by depth, anemone size, A. percula rank 1 size or the number of A. percula in the original group. Instead, we hypothesize that proximity of the A. percula group to the A. perideraion group is a key predictor. Our study demonstrates how long-term observations of tagged individuals and groups could reveal the drivers and consequences of interspecific conflicts on coral reefs.