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Table 2 Distribution of Crepidula fornicata in the intertidal zone of the Milford Haven Waterway in South Wales, UK

From: The distribution of the invasive non-native gastropod Crepidula fornicata in the Milford Haven Waterway, its northernmost population along the west coast of Britain

  SS SS/MStotal df p
Site 17,540.0 33.8 3 <0.001
Tidal height 24,980.6 48.2 2 <0.001
Site × tidal height 5525.9 10.7 6 0.100
   BR CO HA
Mann–Whitney, factor site PE <0.001 0.002 0.162
HA <0.001 0.110  
CO 0.005   
   1.8 m 1.2 m
Mann–Whitney, factor tidal height 0.6 m <0.001 0.001
1.2 m <0.001  
  1. Results of nonparametric two-way crossed Scheirer–Ray–Hare test and Mann–Whitney pairwise comparisons to test for differences in C. fornicata densities between three tidal heights (0.6 m—0.5–0.7 m above Chart Datum; 1.2 m—1.0–1.3 m a. C.D. and 1.8 m—1.5–1.8 m a. C.D.) at four study sites (BR Beggars Reach, CO Cosheston, HA Hazelbeach, PE Pennar). Nonparametric tests were chosen due to heterogeneity in variances that could not be removed with data transformations. Significant differences are shown in bold