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determine the micro-scale (millimetres to centimetres) spatial distributions of marine
macro-invertebrates, mostly using small, contiguous cores, have given important
insights into the proximal factors determining population regulation. Thrush (1991)
reviewed such studies and stated that biological processes were important in giving
rise to patterns at this scale. These processes could be categorised into two groups:
life history characteristics and biotic interactions (e.g., competition, predation and
feeding modes). An example whereby processes from the first category, life history
characteristics, can give rise to micro-scale patterning is the study by Eckman (1979).
Using experimental manipulations and direct observations he showed that the micro-
scale patchiness of several species of the Skagit Bay benthic community was created
and maintained by the hydrodynamic effects of animal tubes affecting the settlement
of new recruits. Lawrie (1996) found that the micro-scale patchiness of Corophium
volutator on the Ythan estuary, Scotland, was generated and maintained by a negative
adult-juvenile association. Competition has been found to result mostly in uniform
distributions in invertebrate species. Levin (1981) observed that the large spionid
Pseudopolydora cf. paucibranchiata had a regular distribution that was firstly
initiated by uniform recruitment patterns and then enhanced by subsequent aggressive
interactions (palp-fighting and biting) between individuals. Similarly, Connell (1963)
suggested that the regular distribution of the amphipod Ericthonius brasiliensis was
due to territorial avoidance by the new recruits and Reise (1979) proposed that the
regular distribution he observed in Hed;ste diversicolor in the intertidal benthos of the
Wadden Sea was also maintained by adult territoriality. However, Reise (1979) also
suggested that the micro-scale patches found in most of the other polychaete species
he studied could be related to their feeding modes. For example, patches of the
carnivorous Anaitides mucosa were correlated with carrion and adult Scoloplos
armiger and Capitella capitata distributions were presumed to result from a
heterogeneous food resource.
The sampling strategies employed to ascertain the spatial patterns of macrobenthic
invertebrate taxa at the small- to meso-scale (meters-10's of meters) have been more
varied. Furthermore, the processes responsible for the patterns observed have been
more difficult to determine but evidence suggests that environmental variables tend to
be predominantly responsible. For example, McArdle and Blackwell (1989) used a
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