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medium grain size. The sediment below these macroalgal mats also became significantly more reduced. While the communities under E. prolifera mats became dominated by C. capitata, those under V. subsimplex mats were dominated by P. elegans. The effect of sediment disturbance on the faunal communities of Drum Sands was investigated by studying the initial colonisation of defaunated sediments. P. elegans numerically dominated the early stages of succession only during periods of high larval availability, C. capitata dominated at other times. Furthermore, P. elegans larval recruitment and adult immigration to defaunated sediments within P. elegans patches were higher compared with non-patch defaunated sediments. The micro-scale spatial distribution of P. elegans within small-scale patches was examined. P. elegans was found to be non-randomly distributed throughout the year, patches formed were commonly less than 3cm2. Correlation analyses implied that these micro-scale patches may have been generated and maintained by adult-juvenile interactions and/or sediment heterogeneity. Small-scale P. elegans patches were found to be distinct ecological areas when compared with surrounding sediments. Sediment properties and invertebrate community structure of P. elegans patches were significantly different to those of non- patch areas. These findings emphasise the ecological importance of patches of tube- building spionid polychaetes in allowing certain species to occur in habitats where they would otherwise be unable to survive. iv
ACKNOWLEDGEMENTS I am indebted to my supervisors Dr. Teresa Fernandes, Professor Paul Read and Dr. Dave Raffaelli for their guidance, encouragement and constructive criticism throughout the course of this study. I am also very grateful to a number of other people for their help in various aspects of my study. These are namely Mike Richards for his help in the field, Jill Sales for her help with statistical analyses, Peter Gibson for helping with faunal identification, Dr. Richard Ladle for reading through and commenting on the thesis, Marina Marcogni for her invaluable help with computing and Dagmar Rothaug and Karen Miller for helping me with fieldwork and sample sorting. I must also thank a number of other people who I have contacted for specialist advice. These are Dr. Simon Thrush for his help during the early stages of my research, Dr. Helgi Gudmundsson and Dr. Torin Morgan for information about Pygospio elegans, Dr. Pierre Legendre for advice about numerical analyses, Dr. Martin Wilkinson for identifying my weed samples and Dr. Steve Hull for his advice about macroalgal mat implantation. I would like to acknowledge my colleagues in the laboratory, my thanks go to them for keeping me 'entertained' over the years. My last thanks, but by no means least, go to Thi for her enduring patience and understanding over the past couple of years.
- Page 1 and 2: AN INVESTIGATION INTO THE PROCESSES
- Page 3: ABSTRACT The spionid polychaete Pyg
- Page 7 and 8: Results. . 65 Size distribution of
- Page 9 and 10: CHAPTER 9. GENERAL DISCUSSION . . 2
- Page 11 and 12: Figure 5.4 Figure 5.5 Figure 6.1 Fi
- Page 13 and 14: LIST OF TABLES Table 2.1 Statistica
- Page 15 and 16: BACKGROUND CHAPTER 1 INTRODUCTION A
- Page 17 and 18: The scales of observation, or the s
- Page 19 and 20: systematic sampling design to inves
- Page 21 and 22: aised sediment within an otherwise
- Page 23 and 24: Fauchald and Jumars (1979) describe
- Page 25: Dalmeny House and sewage discharged
- Page 28 and 29: E 7— E 6-ac. MHWS MHWN t co 4 —
- Page 30 and 31: variance (TTLQV) techniques (see Lu
- Page 32 and 33: analysis using Moran's and Geary's
- Page 34 and 35: Holme and McIntyre (1984). Percenta
- Page 36 and 37: Pattern Analysis - Grid Surveys Sur
- Page 38 and 39: 57 64 1=1 0 0 0 0 0 0 0 O 0 0 0 0 0
- Page 40 and 41: Maps produced by kriging and other
- Page 42 and 43: 200 180 1160 140 100 1-3 80 g 60 c.
- Page 44 and 45: 2.5 1.5 0.5 0 3 T (i) % Silt/clay%
- Page 46 and 47: v : m pattern Id pattern Ip pattern
- Page 48 and 49: " v : m pattern Id pattern Ip patte
- Page 50 and 51: The results show that at the smalle
- Page 52 and 53: Nephtys hombergii's spatial distrib
medium grain size. The sediment below these macroalgal mats also became<br />
significantly more reduced. While the communities under E. prolifera mats became<br />
dominated by C. capitata, those under V. subsimplex mats were dominated by P.<br />
elegans.<br />
The effect of sediment disturbance on the faunal communities of Drum Sands was<br />
investigated by studying the initial colonisation of defaunated sediments. P. elegans<br />
numerically dominated the early stages of succession only during periods of high larval<br />
availability, C. capitata dominated at other times. Furthermore, P. elegans larval<br />
recruitment and adult immigration to defaunated sediments within P. elegans patches<br />
were higher compared with non-patch defaunated sediments.<br />
The micro-scale spatial distribution of P. elegans within small-scale patches was<br />
examined. P. elegans was found to be non-randomly distributed throughout the year,<br />
patches formed were commonly less than 3cm2. Correlation analyses implied that<br />
these micro-scale patches may have been generated and maintained by adult-juvenile<br />
interactions and/or sediment heterogeneity.<br />
Small-scale P. elegans patches were found to be distinct ecological areas when<br />
compared with surrounding sediments. Sediment properties and invertebrate<br />
community structure of P. elegans patches were significantly different to those of non-<br />
patch areas. These findings emphasise the ecological importance of patches of tube-<br />
building spionid polychaetes in allowing certain species to occur in habitats where they<br />
would otherwise be unable to survive.<br />
iv
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