Taxa-specific before-after (BA) effects for (a) Guldborgsund and (b) Stege Bugt (with 95% credibility intervals). Positive or negative effects (on taxa counts per sample) that do not overlap zero are interpreted as showing a change in abundance following the arrival of round gobies. Mean densities per square meter (± s.d.) in samples before and after invasion are also shown for each taxon group. Taxa groupings are arranged by class/phylum groupings by: (from top to bottom) class Bivalvia, class Gastropoda, class Malacostraca, class Polychaeta, class Insecta, phylum Nemertea, class Clitellata, class Bryozoa. Note: Orbiniidae were not detected at Stege Bugt, so were not included in analysis for that site.