To determine behavioural stress, polyp activity states of Primnoella chilensis colonies and the frequency of these states were observed under turbid seawater in an experimental setup for 15 days (Treatment 1: equals sedimentation rate of 225 mm/y; Treatment 2: equals sedimentation rate of 450 mm/y; control group: ambient seawater). A visual overview analysis of colonies of Primnoella chilensis was conducted with the image-viewing program IrfanView. In a defined sector the overall colony activity was assessed and categorized: category 0 = > 50 % of polyps closed; category 1 = > 50 % of polyps semi-open; 2 = > 50 % of polyps open ; x = no data.

This dataset was generated in the frame of the co-operation between the Huinay Scientific Field Station (http://www.huinay.cl) and the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (http://www.awi.de).