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Meeting Abstract

SICB+   -   Social distancing before it was cool: Fine-scale spatial distribution of the sea anemone Anthopleura sola Ramamurthy, SV*; Kuris, AM; University of California, Santa Barbara; University of California, Santa Barbara

Aggressive interactions can influence the spatial distribution pattern of a population; for example, intraspecific aggression can lead to uniform species distributions. However, the ecological role of intraspecific aggression has been poorly studied in sea anemones. Anthopleura sola is a solitary, sexually reproducing sea anemone that inhabits rocky intertidal ecosystems from northern Baja California to Bodega Head, California. This species displays intraspecific agonistic behavior upon tentacular contact with other individuals. Here, we document the spatial distributions of A. sola in the rocky intertidal ecosystem and hypothesize that populations will be uniformly distributed at fine scales due to intraspecific aggression. The position of each individual sea anemone was recorded within aggregations of A. sola across different microhabitats, including two-dimensional areas and linear rock fissures. To test for deviations from spatial randomness, we employed both point-pattern as well as finite-size object analysis. Preliminary data indicate that the distributions of A. sola tend towards uniformity at fine scales and that treating individuals as discs can yield different spatial patterns than treating them as points. Additionally, we observe that some individuals settle in close proximity to others, contrary to what would be expected considering their intraspecific aggressive behavior. Our findings suggest that in addition to intraspecific aggression, physiological habituation and habitat heterogeneity may also play important roles in influencing sea anemone distribution patterns in the rocky intertidal ecosystem. Ongoing work involves characterizing the spatial distributions of A. sola at different sites.