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This study had 3 main aims, these were:
CHAPTER 9
GENERAL DISCUSSION
• To determine the spatial distribution of P. elegans on Drum Sands;
• To investigate the processes affecting P. elegans densities and the possible role of
these processes in the formation and maintenance of small-scale patches;
• To assess the ecological importance of the spatial distribution of P. elegans on
Drum Sands.
These 3 main aims have been successfully fulfilled by the surveys and controlled
experiments performed on Drum Sands and are now discussed separately.
The spatial distribution of P. elegans on Drum Sands, Firth of Forth, Scotland.
Irrespective of the field of study, all marine ecologists are faced with the problem of
establishing and quantifying patterns in nature since they are the building blocks of the
models from which hypotheses are generated (Andrew and Mapstone, 1987). In the
first part of the present study, the small-scale (metres) and meso-scale (tens of metres)
spatial patterns of P. elegans were determined, followed by an investigation of the
micro-scale (centimetres) spatial patterns. The small- and meso-scale patterns were
considered in Chapter 2 and the micro-scale patterns in Chapter 7.
In Chapter 2 the presence of areas of smooth, raised sediments observed on Drum
Sands were confirmed by spatial surveys to be areas of significantly higher densities
of P. elegans. These 'patches' were found to be approximately 1-1.5m 2 and were
randomly distributed. The detection of these patches was crucial to all later studies
described within this thesis since these studies depended upon the presence of
significantly increased numbers of P. elegans within patches compared with non-
patch sediments.
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