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exhibited by the tube-building polychaete has an effect upon the spatial pattern of other species. Species with similar structure functions (correlograms) do not necessarily occupy the same spatial locations (Hewitt et al., 1996). For example, while the correlograms of P. elegans, L. conchilega, B. sarsi and N. hombergii suggested that these species formed patches of increased densities approximately 1-1.5m2, their density plots revealed that their patches were not spatially correlated. For P. elegans, this was examined more formally using correlation analyses which supported the observations that P. elegans abundances were not correlated with the abundances of L. conchilega or M. balthica (B. sarsi and N. hombergii were not considered sufficiently abundant for correlation analyses). This suggests that the spatial patterns of P. elegans on Drum Sands did not have a large positive effect on those of the other common species. Pygospio elegans was only positively correlated with one species in this study, M. balthica (8m and 40m surveys). However, positive association does not necessarily imply a positive interaction, since negative interactions (e.g., predation) can take place between species coincident in space, or coincidence may occur due to some common ecological preference between two species. Controlled manipulative experiments, together with spatial autocorrelation analysis, are needed to test explicitly for the presence of an interaction between these two species. Tube-building polychaetes are capable of affecting species distributions via many direct and/or indirect interactions, e.g., hydrodynamic effects (Eckman et al., 1981; Eckman, 1983), provision of refuges (Woodin, 1978, 1981; Lukenbach, 1986) and increased food availability (Eckman, 1983; Noji, 1994) which suggest that the positive association between P. elegans and M. balthica in this study may have been non- coincidental. A change in spatial pattern of M. balthica or reduced survival, growth or recruitment may, therefore, be expected in the absence of P. elegans. The processes by which P. elegans affect other fauna are discussed further in Chapter 8 in which the faunal communities and sediment variables of P. elegans patches are compared with non-patch sediments using not a non-parametric correlation approach as in this study but a more suitable, parametric method of statistical analysis, i.e., t-tests. 57
The study described here has provided important information about the spatial patterns exhibited by the abundant invertebrate species on Drum Sands. The results have provided invaluable information from which hypotheses can be tested about the generation of spatial patterns on intertidal sandflats, in particular, the small-scale patches formed by P. elegans and the role they play in structuring the community. 58
Page 1 and 2:
AN INVESTIGATION INTO THE PROCESSES
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ABSTRACT The spionid polychaete Pyg
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ACKNOWLEDGEMENTS I am indebted to m
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Results. . 65 Size distribution of
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CHAPTER 9. GENERAL DISCUSSION . . 2
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Figure 5.4 Figure 5.5 Figure 6.1 Fi
Page 13 and 14:
LIST OF TABLES Table 2.1 Statistica
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BACKGROUND CHAPTER 1 INTRODUCTION A
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The scales of observation, or the s
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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
Page 54 and 55: (vii) G. duebeni (ix) % Organic con
Page 56 and 57: 8m survey - spatial patterns Figure
Page 58 and 59: (1) P. elegans (iii) L. conchilega
Page 60 and 61: a) Ts 1.4 0.6 u 0.2 -0.2 1.4 'E5 0.
Page 62 and 63: 200m 150m 100m 50m (ix) C. edule 56
Page 64 and 65: 73 ‘a• el 1.4 (ix) G. duebeni 1
Page 66 and 67: DISCUSSION The main aims of this st
Page 68 and 69: formed patches less than 1m2 and th
Page 70 and 71: stutchbutyi, at Wirroa island, New
Page 74 and 75: CHAPTER 3 THE POPULATION STRUCTURE
Page 76 and 77: Asexual reproduction by fragmentati
Page 78 and 79: METHODS Survey design - It has been
Page 80 and 81: RESULTS The species abundances in e
Page 82 and 83: corresponds to 44 setigers using Eq
Page 84 and 85: 1 0000000 00 rg 0 00 d- - Xauanbau
Page 86 and 87: Reproductive activity of Pygospio e
Page 88 and 89: P. elegans larvae at Drum Sands hav
Page 90 and 91: Pygospio elegans showed great seaso
Page 92 and 93: Previous studies have produced simi
Page 94 and 95: The sole reliance on a planktonic m
Page 96 and 97: abundance are highly seasonal, were
Page 98 and 99: CHAPTER 4 THE EFFECTS OF MACROALGAL
Page 100 and 101: studies may have been completely di
Page 102 and 103: METHODS Study site - The exact posi
Page 104 and 105: 1 C N W 4----111" 1.5m 2 NW C Contr
Page 106 and 107: sediment sampling, together with re
Page 108 and 109: RESULTS Species abundances - The me
Page 110 and 111: ; 15 35 — 30 — 25 — 10 — 5
Page 112 and 113: statistical difference from net plo
Page 114 and 115: Pygospio elegans size distribution
Page 116 and 117: used, approximately equivalent to t
Page 118 and 119: artefacts associated with the metho
Page 120 and 121: present in high numbers around sewa
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lack, hydrogen sulphide-smelling se
Page 124 and 125:
CHAPTER 5 THE EFFECTS OF MACROALGAL
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METHODS Survey design - During late
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The sediments could not be sampled
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RESULTS Species abundances - Table
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90 — 80 — "-e-' 70 — 60 — 4
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35 — *** 30 25 — 1.) = .-c‘l
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Pygospio elegans size distributions
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which is difficult to compare with
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eason why some invertebrates showed
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This study did not set out to expli
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This reliance upon the early establ
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CHAPTER 6 INITIAL COLONISATION OF D
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esulting community at any stage of
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ambient sediment had been removed.
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emoved since they were the only tax
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All statistics were performed using
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RESULTS Univariate analysis of spec
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3.5 3 5 2 11 5 1 0.5 0 40 35 Ca 30
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of non-patch areas (Figure 6.3(vi))
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the individuals colonising patch az
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Multivariate analysis of community
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Month Sample statistic (Global R) N
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2NP 3NP 4NP .•,, 6NP 5NP 6P 1NP i
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Figure 6.8: Two-dimensional MDS ord
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- - 5P ... 4P . 6P • .‘2NP 1NP
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I 50. 1 60. 70. 80. 90. 100. BRAY-C
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'P2-AZ P3-AZ N2-AZ .- - - " .„ ..
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o • o -o + 350 — 300 = 250 7 g
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The importance of the ambient commu
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In April, when P. elegans larval av
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not only for errant polychaetes, bu
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observed in this study. How crucial
Page 188 and 189:
Micro-scale spatial patterns of mac
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METHODS Experimental design - A pre
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study. These individuals would not
Page 194 and 195:
RESULTS Pilot survey - The pilot su
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Transect survey - Micro-scale patte
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Month v:m ratio pattern Id pattern
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(i) March 1997, replicate 1 -iAlmiA
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(xix) October 1997, replicate 1 (ra
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The new recruits were only sufficie
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The results of correlation analyses
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cf.) . crt N ,—, Cr) C,1 ,—, Cr
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1.2 -0.4 "a 0.8 > (i) % Water conte
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examine the micro-scale spatial pat
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Invertebrate larvae, those of polyc
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laboratory observations are needed
Page 218 and 219:
CHAPTER 8 THE FAUNAL COMMUNITIES OF
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Other theories have been postulated
Page 222 and 223:
RESULTS Univariate analysis of spec
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-T. g 80 g 50 40 30 20 10 (i) Adult
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in significant differences in size
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8.2). This was mainly because of th
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120 100 80 60 - 40 20 0. cn1 c.n (i
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3NP 6NP 4NP 1 NP 5NP 2NP : 3P 1P 6P
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4P 3P 5P 5NP 6P 2P 1P Figure 8.8: T
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Figure 8.10 shows the dendrogram pr
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NP1 NP2 NP2 NP2 NP1 NP1 NP2 NP2 NP2
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Sediment water, organic and silt/cl
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5 350 — 300 250 200 — ISO — 1
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abundances of P. ciliata had more d
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levels of silt/clay and organics. S
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1973; Noji and Noji, 1991). Competi
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shown to consume up to 68% of a 0-g
Page 252 and 253:
In Chapter 7 the micro-scale spatia
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and positions of patches. Consequen
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epresent those found establishing i
Page 258 and 259:
distribution at the micro-scale. Ad
Page 260 and 261:
provide a rich food source for deme
Page 262 and 263:
Armonies W., 1988. Active emergence
Page 264 and 265:
Cha M.W., in prep. Macroalgal mats
Page 266 and 267:
Dobbs F.C. and Vozarik J.M., 1983.
Page 268 and 269:
Flach E.C., 1996. The influence of
Page 270 and 271:
Hall SI, Raffaeni D.G., Basford DJ.
Page 272 and 273:
Keckler D., 1997. Surfer for Window
Page 274 and 275:
Levin L.A. and Creed E.L., 1986. Ef
Page 276 and 277:
Mileikovsky S.A., 1971. Types of la
Page 278 and 279:
Ong B. and Krishnan S., 1995. Chang
Page 280 and 281:
Raffaelli D.G., Hildrew A.G. and Gi
Page 282 and 283:
Scheltema R.S., 1974. Biological in
Page 284 and 285:
Soulsby P.G., Lowthion D., Houston
Page 286 and 287:
McArdle B.H., Morrisey D., Schneide
Page 288 and 289:
Wharfe J.R., 1977. An ecological su
Page 290 and 291:
Zajac R.N. and Whitlatch R.B., 1982
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- C'e) oc0000mooF,o•-ooNtn-coo-00
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APPENDIX 1.2: SPECIES ABUNDANCES FR
Page 296 and 297:
ON In co In ° ken n00000N---0g0N-.
Page 298 and 299:
o m000eno,-0-. 0 0000en ,-. 0.-00 o
Page 300 and 301:
APPENDIX 2: SPECIES ABUNDANCES FROM
Page 302 and 303:
0.- CV N - , .- CI E.104 ..r cv g.,
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cv en 0 a .- ,- .- .- g c', ,- ,- g
Page 306 and 307:
PI — — — Pi n — — - R., .
Page 308 and 309:
P . en .2 Co in ,.. ne .- cq . -- -
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