New Zealand Journal of Marine and Freshwater Research abstracts

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Validation of qualitative habitat descriptors commonly used to classify subtidal reef assemblages in north-eastern New Zealand

N. T. Shears¹
R. C. Babcock^1,2
C. A. J. Duffy³
J. W. Walker¹

¹Leigh Marine Laboratory
University of Auckland
P.O. Box 349
Warkworth, New Zealand
email: n.shears@auckland.ac.nz

²CSIRO Marine Research
Private Bag No. 5
Wembley, WA 6913
Australia

³Department of Conservation
Science and Research Unit
P.O. Box 112
Hamilton, New Zealand

Abstract  On shallow temperate subtidal reefs, habitat types are usually defined subjectively by the dominance or presence of major macroalgal species. Many of these habitat types (e.g., urchin barrens, kelp forest) are frequently used in the literature but little attempt has been made to quantitatively define these habitats. A survey of shallow subtidal reefs in north-eastern New Zealand identified a number of commonly occurring “habitat types”. In this paper the abundances of habitat-forming species within each of these habitats are quantified and the validity of the subjective classification system is tested. In addition to previously-described reef habitats from north-eastern New Zealand a number of other habitat types were encountered and described in this study (e.g., “mixed algae”, “red foliose algae”, and “Caulerpa mats”). The algal communities within each habitat were biologically distinct and there was strong concordance between the grouping of samples from cluster analysis and the subjective habitat type assigned to each. The habitat classification system was reliable and canonical analysis of principal coordinates revealed an overall classification success of 81%. This provides strong evidence that the habitat classifications used in this study are biologically meaningful based on the abundances of habitat-forming algal groups. Furthermore, this demonstrates that these habitat types can be reliably categorised visually, which has important applications in classification and mapping of the marine environment.

Keywords  habitat classification; kelp forest; macroalgal assemblages; temperate reefs; urchin barrens

M03077; Received 12 November 2003; accepted 17 May 2004; Online publication date 5 August 2004
New Zealand Journal of Marine and Freshwater Research, 2004, Vol. 38: 743-752
0028-8330/04/3804-0743 © The Royal Society of New Zealand 2004

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