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Abstract

The formation of small-scale barrens of sea urchins on the east coast of Tasmania allows for direct comparison of the growth rates and age structures of sea urchin populations in barrens and habitats dominated by native macroalgae. However, such barrens are atypical of any previously described in temperate regions worldwide mainly because of the establishment and seasonal colonization by the introduced macroalga Undaria pinnatifida. Growth models were fitted to sea urchin (Heliocidaris erythrogramma) data, based on tag-recapture information from two distinct community types, a native macroalgal bed and a sea urchin barren colonized by U. pinnatifida. Despite the distinct contrast in habitats, size-at-age relationships and age frequency distributions were not significantly different between the two populations. However, the relationship between jaw length and test diameters was significantly different between populations, sea urchins in barrens possessing larger jaws relative to conspecifics of similar test diameter in native macroalgal habitats. It is proposed that the growth of sea urchins on barrens is not adversely affected by the loss of native macroalgae in the presence of U. pinnatifida. However, sea urchins display a level of resource limitation in barrens because of differences in the relationships of sea urchin morphometrics.

Item Type:	Article
Authors/Creators:	Pederson, HG and Johnson, CR
Keywords:	age structure, barrens habitat, growth, Heliocidaris erythrogramma, size structure, Undaria pinnatifida
Journal or Publication Title:	ICES Journal of Marine Science
Publisher:	Oxford University Press
ISSN:	1054-3139
DOI / ID Number:	10.1093/icesjms/fsm168
Additional Information:	Copyright 2008 ICES/CIEM International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer.
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