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The large increase in interest concerning the study of spatial patterns of species and
communities has undoubtedly partly resulted from the expansion of techniques
available for quantitatively and qualitatively assessing patterns. Most of these
techniques, for example, quadrat-variance (Greig-Smith, 1952; Upton and Fingleton,
1985), spatial autocorrelation analysis (Cliff and Ord, 1973), mapping (Burrough,
1987), spatially-constrained clustering (Legendre and Fortin, 1989) and ordination
(Wartenberg, 1985; Ter Braak, 1986) and semi-variogram analysis (see review by
Legendre and Fortin, 1989) were developed by plant ecologists and have been adapted
for use in other areas of ecology. Many of these techniques have been employed in
the study of spatial patterns in the marine benthic environment.
Pattern and observational scale are intrinsically linked (Addicott et al., 1987; Levin,
1992; Platt and Sathyendranath, 1992; Hall et al., 1993; Lawrie, 1996). Patterns
evident at one scale can either disappear or appear as noise when viewed at other
scales (Eckman, 1979; Valiela, 1984; McArdle et al., 1990; Dutilleul and Legendre,
1993; Thrush et al., 1997a). This is because the processes which give rise to patterns
in nature are scale-dependent (Legendre et al., 1997; Thrush et al., 1997b). For
example, non-overlapping distributions of two species at one scale may reflect
interspecific competition while at larger scales, a positive association between the two
species may result from habitat selection (Wiens, 1989). Consequently, studying the
relationship between the pattern observed and the process creating that pattern is
problematical (McArdle et al., 1997; Thrush et al., 1997a, 1997b). Levin (1992) and
Thrush et al. (1997c) suggested that recognition that different processes are relevant at
different scales precludes the reductionist approach of sampling at the 'right' scale
(e.g., Wiens, 1989; Kotliar and Wiens, 1990). Consequently, they proposed that
ecologists should ask the question of how we can draw conclusions from one scale to
another. Often, however, the scale at which one samples depends upon the questions
one is attempting to answer within a particular study or upon logistical constraints.
McArdle and Blackwell (1989) and Legendre et al. (1997) suggested that a good
starting point before planning an experiment is the identification of the patterns that
can be detected at one or several spatial scales.
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