Defense strength as log effect ratio against microfouling by Bacillus sp., Cytophaga sp. and Vibrio sp. (averaged). Effect size > 0 indicates an attractive effect of surface-bond metabolites, effect size < 0 an inhibitory effect with the strongest defense at lowest values. Responses are detailed with regards to the four treatments: warm (+°C (delta+5)), acidified (-pH (delta +700µatm pCO2)), warm and acidified (+°C -pH), and ambient during four seasons: spring, summer, autumn, winter (n=3).The data set comprised 4 experimental runs: spring experiment (4.4.-10.6.2013), summer experiment 1 (4.7.-17.9.2013), autumn experiment (11.10-16.12.2013), winter experiment (16.1. - 28.3.2014).