Table 2. Differences in pre- and post-mortality benthic assemblages.
The four taxa that contributed disproportionately to dissimilarity in benthic community composition on rocky reefs before and after the 2013 sea star mass mortality, as well as the focal sea star, Pycnopodia helianthoides. Mean densities (# per 30 m2 ± 1 SD), consistency ratios, and individual and cumulative contributions (in %) to differences between years are shown. The consistency ratio is calculated as a species’ average dissimilarity contribution divided by the standard deviation of dissimilarity values. A consistency ratio > 1 indicates an even contribution to community dissimilarity across sites. The analysis was conducted on square-root-transformed data (see Methods) but untransformed densities are presented here.
| Taxon | Mean density (SD) | Consistency ratio | Individual contribution | Cumulative contribution | |
|---|---|---|---|---|---|
| Before | After | (%) | (%) | ||
| Strongylocentrotus droebachiensis | 18.3 (41.0) | 77.2 (157.5) | 1.09 | 18.91 | 18.91 |
| Cup corals | 6.7 (15.8) | 22.2 (19.1) | 1.41 | 13.04 | 31.95 |
| Misc. shrimps | 37.0 (38.7) | 15.9 (11.2) | 1.3 | 11.29 | 43.23 |
| Misc. crabs | 21.7 (35.0) | 16.3 (23.5) | 1.05 | 11.15 | 54.38 |
| Pycnopodia helianthoides | 6.4 (11.4) | 0.9 (3.3) | 1.18 | 7.15 | 69.05 |