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examine the micro-scale spatial patterns of spionids in soft sediments. Different inter-
individual patterns have been observed which have been related to, and supposedly
generated by, intraspecific interactions. For example, Levin (1981) found individuals
of Pseudopolydora cf. paucibranchiata to be uniformly distributed on the intertidal
mudflats of Mission Bay, San Diego. She suggested, following observations on its
feeding behaviour, that this distribution in this large, aggressive spionid resulted from
defensive behaviour and guarding of food, space and tube-building materials. She
also found that Streblospio benedicti, a smaller spionid polychaete, was randomly
distributed suggesting a greater tolerance to intraspecific encounters. However, at
their highest densities, 16,500/m2, Levin (1981) found that S. benedicti was also
uniformly distributed indicating some density-dependent competition. Morgan (1997)
found, by superimposing a 10x10 grid of 2mm 2 squares onto the surface of a larger
core, that P. elegans was randomly distributed at high densities (47,500/m2-
82,500/m2). That P. elegans did not exhibit a uniform distribution at these densities
suggested that this species was very high-density tolerant, in contrast to P. cf.
branchiata and S. benedicti, the latter being similar in size and having a similar
feeding behaviour to P. elegans. This is supported by the observations of Brey (1991)
who reported no signs of aggressive behaviour between P. elegans individuals.
It is difficult to relate the present findings with those of the above studies because of
sampling-scale differences. Since P. elegans abundances were too low to sample at
the scale of an individual's influence (i.e., 2mm 2) in this study, the results cannot
unequivocally be compared with the results of Morgan (1997) or the plotless sampling
methods of Levin (1981). For example, plotless sampling, within the micro-scale P.
elegans patches observed in this study, might have revealed a localised uniform
distribution (and hence possibly negative intraspecific interactions) and similarly,
sampling with 3cm 2 cores in the studies by Levin (1981) and Morgan (1997) might
have revealed clumped distributions in much the same way as in the present study.
The relatively low overall P. elegans densities within small-scale patches on Drum
Sands indicated that in order to investigate the inter-individual spatial distribution and
hence provide evidence for intraspecific interactions, plotless sampling would have
been necessary. However, what this study has revealed is the presence of micro-scale
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