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Abstract

Relationships between different metrics of reef structure and the density of macroinvertebrates
were examined at 3 nested spatial scales inside and outside a long-established, ‘no-take’
marine protected area (MPA) at Maria Island, Tasmania, Australia. Generalized linear models were
developed that best explained the contributions of rugosity, substratum composition (different-sized
boulders, bedrock, sand) and refuge metrics to the spatial variability in invertebrate species richness,
total abundance, and the abundances of major taxonomic classes and focal species. To distinguish
responses associated with protection from fishing from those relating to natural geographic variation,
relationships between reef structure and invertebrate density were also assessed using survey data
from before the MPA came into effect. Models combining reef structure and MPA protection
explained between 44 to 67% of spatial variability of total invertebrate abundance across all survey
scales examined (1 × 5, 1 × 50 and 1 × 200 m). The number of refuge size categories provided the best
predictor of invertebrate species richness at the 5 m scale; however, no reef structure metric investigated
was significant at the largest (200 m) spatial scale for species richness. Amongst the explanatory
variables examined, MPA protection and density of small refuges generated significant
responses for the majority of taxa. One commonly applied metric of reef structure, rugosity, was
found to be a relatively poor predictor of invertebrate abundance and richness, generating few significant
relationships. Comparisons with pre-MPA data indicated that protection from fishing greatly
influenced most major components of the invertebrate community, while reef structure appears to
have little interactive influence on these MPA effects at the scales tested here.

Item Type:	Article
Authors/Creators:	Alexander, TJ and Barrett, NS and Edgar, GJ and Haddon, M
Keywords:	Rugosity · Spatial refuges · Marine protected area · Sea urchins · Crinoids ·Generalized linear model · Species richness · Tasmania
Journal or Publication Title:	Marine Ecology Progress Series
ISSN:	0171-8630
DOI / ID Number:	10.3354/meps08210
Additional Information:	Copyright © 2009 Inter-Research
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