New Zealand Journal of Marine and Freshwater Research abstracts
Assemblage structure, spatial patterns, recruitment, and post-settlement
mortality of subtidal bivalve molluscs in a large harbour in north-eastern
New Zealand
R. G. COLE*
P. J. HULL
T. R. HEALY
Marine Geosciences Group
Department of Earth Sciences
University of Waikato
Private Bag 3105
Hamilton, New Zealand
email: r.cole@niwa.cri.nz
*Present address: National Institute of Water &
Atmospheric Research Ltd, P. O. Box 893, Nelson, New Zealand.
Abstract Infaunal bivalve molluscs on the flood tidal delta
of Tauranga Harbour, north-eastern New Zealand, were surveyed twice over a
6-month period, with the aim of assessing shellfish resources, assessing the
magnitudes of temporal and spatial variability in abundances, and identifying
potentially important processes. The surveys identified a total of 31 bivalve
taxa from 27 sites. Species richness per site ranged between 0 and 9, and
varied greatly in space and time, as did two other measures of diversity.
Extremely high densities of bivalves (>20 000 m-2) were
encountered at several sites. Densities of several abundant species varied
greatly in time, as a result of recruitment pulses. The abundances of the three
species that dominated the fauna (Paphies australis, Tawera
spissa, and Ruditapes largillierti) had characteristic spatial
scales on the order of 200 m. Comparisons of size frequency distributions
for individual sites suggested that mortality or emigration in the first year
of benthic life was high. Substantial populations of bivalves occur on Centre
Bank, and the most abundant of these are greatly influenced by events early in
their lives.
Keywords clams; infauna; population dynamics; spatial
autocorrelation analysis
M99018
Received 1 April 1999, accepted 27 October 1999
PDF file of entire paper: medium quality (846K); (scanned from paper original: notes about this process)
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