Habitat-dependent growth in a Caribbean sea urchin Tripneustes ventricosus: the importance of food type

Table 1 Test diameters of Tripneustes ventricosus urchins in two habitats, reef and seagrass

Sampling date	Mean (± SE) test diameter (mm)		Median test diameter (mm)		U	P
Sampling date	Reef	Seagrass	Reef	Seagrass	U	P
November 2000	90.1 ± 2.0	75.4 ± 1.5	97.8	80.4	7614	<0.001
February 2002	81.3 ± 2.0	83.7 ± 1.2	84.2	84.7	2514	0.789
July 2002	74.5 ± 2.1	84.1 ± 0.7	81.8	83.6	5577.5	0.316
July >75 mm reef versus all seagrass	92.2 ± 0.9	84.1 ± 0.7	92.1	84.2	4407.5	<0.001
July >75 mm reef versus >75 mm seagrass	92.2 ± 0.9	85.3 ± 0.6	92.1	84.2	3967.5	<0.001

In July 2002 subsamples of urchins with test diameters >75 mm were used in some analyses (see text and Fig. 3) Mann–Whitney U tests compared test diameters between habitats within a sampling period. Probabilities were corrected with the sequential Bonferroni method (Rice 1989)
Statistically significant differences are indicated in boldface

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