The introduced clam Ensis americanus in the Wadden Sea: field experiment on impact of bird predation and tidal level on survival and growth

Table 2 Analysis of covariance of growth rates of E. americanus: Effect of plot-type (HSS [+]/LSS [−]/LSS [+]) on growth rate [ln (length_t=60/length_t=0)] of clams with initial shell length [ln (length_t=0)] as covariate

Source of variation	df	MS	F-ratio	P value
Treatment: [HSS+/LSS−/LSS+]	2	0.003	11.447	0.000
Covariate:ln (initial length)	1	0.044	153.774	0.000
Error	97	0.000
Total	101

Prior to this analysis it was shown that there was no interaction (common slope) between regressions of growth rate on initial length of clams from the different plot-types. Furthermore all regression lines were significant and with r ²-values around 60%
df Degrees of freedom, MS mean square

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