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aised sediment within an otherwise wave-rippled sandflat. This study has 3 main
aims, these are:
• 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 aims were addressed by carrying out surveys and experimental manipulations
on Drum Sands, these are discussed in more detail below.
In Chapter 2, the small- to meso-scale (metres-10's metres) spatial patterns of P.
elegans within a relatively homogeneous area of Drum Sands were investigated to
explicitly determine the sizes of the P. elegans patches, their position, and worm
density within them. The spatial patterns of other common taxa were also determined,
together with sediment variables, in order to assess whether interspecific interactions
and/or abiotic factors were likely to be important processes affecting the spatial
distribution of P. elegans.
The population dynamics and reproductive biology of P. elegans on Drum Sands were
considered in Chapter 3 together with their possible role in patch formation and
maintenance. An understanding of the population dynamics and reproductive biology
of this population was necessary in view of the reproductive variability found within
this species.
The ecological effects of macroalgal mat formation on intertidal sandflats were
investigated in Chapters 4 and 5. In these chapters, the potential role of macroalgal
mat establishment in the formation and maintenance of P. elegans patches is
discussed. This was achieved by both a controlled weed-implantation experiment
(Chapter 4) and a descriptive survey (Chapter 5).
In Chapter 6, the role of sediment disturbance on intertidal sandflats is addressed.
Using small-scale patches of P. elegans, the effects of dense assemblages of biogenic
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