Meeting Abstract

6.6  Sunday, Jan. 4  Spatial aggregation promotes species coexistence among corals: Evidence from experiments and modeling IDJADI, Joshua*; KARLSON, Ronald; New England Aquarium; University of Delaware jidjadi@neaq.org

Scleractinian coral species with varying competitive abilities often occur in communities where shared resources are limited. Despite this, these communities can be very diverse, without dominance by the best competitors. We experimentally tested the role of spatial heterogeneity, specifically the spatial arrangement of competitors, in promoting species coexistence among corals. Using a strong competitor (Porites rus) and a weaker one (P. lobata) we addressed the hypothesis that when corals are intraspecifically aggregated, coexistence is increased. When these corals were placed into artificial competitive neighborhoods, weaker competitors grew at almost twice the rate when they were grown in aggregated versus non-aggregated patterns. Further experimental work suggested that aggregation is most important when there is no refuge from competition for weaker competitors. The results of these experiments were extrapolated to larger spatial and temporal scales by a cellular automata model. The persistence of weaker competitors was increased substantially when the beneficial effect of aggregation was applied to this model system. This research adds to evidence from other work in plant systems that spatial arrangement can promote species coexistence in competitive, resource limited communities.