Dataset: Eunicea flexuosa interactions

Methodology from Gambrel, B. and Lasker, H.R., 2016

Since physical effects of octocoral−octocoral proximity were common, we examined the physical effects on different species by comparing their interspecific interactions with 75 colonies of E. flexuosa. The choice of E. flexuosa was based on its abundance and on the reliability of identifying E. flexuosa colonies in the field. We sampled at East Cabritte, as the high octocoral density there led to a high incidence of interactions. We searched for E. flexuosa within the same 500 m2 area as the belt transects and selected colonies based on the presence of interspecific interactions. Tissue damage due to proximity between octocorals was categorized into first and second-degree damage. First-degree damage was defined as slight signs of abrasion including fewer polyps or retracted polyps in contact areas and lightly eroded calyces, whereas second-degree damage involved the erosion of the soft tissue past the surface layer, sometimes down to the proteinaceous skeleton. If an octocoral had branches exhibiting both first and second-degree damage, it was scored as having the more severe, second-degree damage. Colonies in close proximity were identified to species and were assessed for damage and asymmetry. Fisher’s exact tests of independence were used in R to test for the effect of the species pairing on damage type and the presence or absence of colony asymmetry.