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ambient sediment had been removed. The locations of the defaunated sediments were chosen randomly. This approach allowed the exact position of the treated sediments to be relocated when later sampled and overcame the need for marking them with sticks which would have had hydrodynamic effects. This method was previously tested and the positions of the cores were located exactly (n=12). The outermost sections within the quadrat were ignored to minimise edge effects. I m I m CONTROL CORE (AMBIENT SEDIMENT) AZOIC SEDIMENT CORE FROM AZOIC SEDIMENT AREA OF HIGH PYGOSPIO NUMBERS I m Non-patch plot s8cm Figure 6.1: Experimental layout of patch and non-patch plots. One patch plot and one non-patch plot are shown in detail while 6 replicates of each were used in each experiment. The 'control cores' (ambient sediment) shown were taken as part of a separate study (Chapter 8) but the results provide useful information as to the background densities of species for this study. 135
The size of the defaunated sediment core was chosen to approximately represent the area disturbed by small-scale disturbances such as the pits created by feeding flatfish. The scale of disturbance has been shown to result in different successional dynamics only when the disturbed area varies in size by many orders of magnitude (Wilson, 1992; Ragnarsson, 1996). Therefore, although the size of the disturbed areas in this experiment was slightly larger than those created by flatfish, similar successional dynamics would be expected. The sediment cores were implanted without the corers so as not to restrict immigration of infauna from below the sediment surface which would be possible after a natural disturbance. The treatment and implanting of the sediments were identical for both patch and non-patch plots. The treated sediments were left for 3 weeks before sampling. This time interval was chosen from the results of preliminary studies carried out in March 1997, together with the information obtained on colonisation rates following disturbances at this scale provided by literature review (e.g., Zajac and Whitlatch, 1982a; 1982b; Levin, 1984a; Savidge and Taghon, 1988; Frid, 1989; Hall et al., 1991; Wilson, 1992; 1994; Ragnarrson, 1996). Preliminary studies involved implanting defaunated sediments for 1, 2, and 3 weeks - only after 3 weeks was there a large increase in colonists (C. capitata and P. elegans) in both P. elegans patches and non-patches (n=6). Furthermore, since one of the aims of this experiment was to determine mode of colonisation, it was important to allow colonisation to proceed for as short a time as feasibly possible. The implanted sediments were sampled after 3 weeks by an 8cm internal diameter corer to a depth of 12cm. Each sample was then sectioned into 2 parts. The top 3cm were removed and preserved in neutralised 10% saline formaldehyde solution with 0.01% Rose Bengal. These samples were later washed through a 500pm and 212pm mesh sieve stack in the laboratory. An elutriation method was used to help remove the fauna from the sediment retained by the 2121.1,m mesh sieve before sorting. This 4- decantation elutriation method separated all the fauna from the sediment (n=25) apart from a small number of nematodes which were not analysed. The elutriant was again sieved on a 2121.1m mesh sieve and juvenile P. elegans and C. capitata removed under a dissecting microscope (x10 magnification). These were the only two species 136
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
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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
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aised sediment within an otherwise
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Fauchald and Jumars (1979) describe
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Dalmeny House and sewage discharged
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E 7— E 6-ac. MHWS MHWN t co 4 —
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variance (TTLQV) techniques (see Lu
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analysis using Moran's and Geary's
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Holme and McIntyre (1984). Percenta
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Pattern Analysis - Grid Surveys Sur
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57 64 1=1 0 0 0 0 0 0 0 O 0 0 0 0 0
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Maps produced by kriging and other
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200 180 1160 140 100 1-3 80 g 60 c.
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2.5 1.5 0.5 0 3 T (i) % Silt/clay%
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v : m pattern Id pattern Ip pattern
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" v : m pattern Id pattern Ip patte
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The results show that at the smalle
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Nephtys hombergii's spatial distrib
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(vii) G. duebeni (ix) % Organic con
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8m survey - spatial patterns Figure
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(1) P. elegans (iii) L. conchilega
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a) Ts 1.4 0.6 u 0.2 -0.2 1.4 'E5 0.
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200m 150m 100m 50m (ix) C. edule 56
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73 ‘a• el 1.4 (ix) G. duebeni 1
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DISCUSSION The main aims of this st
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formed patches less than 1m2 and th
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stutchbutyi, at Wirroa island, New
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exhibited by the tube-building poly
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CHAPTER 3 THE POPULATION STRUCTURE
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Asexual reproduction by fragmentati
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METHODS Survey design - It has been
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RESULTS The species abundances in e
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corresponds to 44 setigers using Eq
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1 0000000 00 rg 0 00 d- - Xauanbau
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Reproductive activity of Pygospio e
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P. elegans larvae at Drum Sands hav
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Pygospio elegans showed great seaso
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Previous studies have produced simi
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The sole reliance on a planktonic m
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abundance are highly seasonal, were
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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
Page 122 and 123: lack, hydrogen sulphide-smelling se
Page 124 and 125: CHAPTER 5 THE EFFECTS OF MACROALGAL
Page 126 and 127: METHODS Survey design - During late
Page 128 and 129: The sediments could not be sampled
Page 130 and 131: RESULTS Species abundances - Table
Page 132 and 133: 90 — 80 — "-e-' 70 — 60 — 4
Page 134 and 135: 35 — *** 30 25 — 1.) = .-c‘l
Page 136 and 137: Pygospio elegans size distributions
Page 138 and 139: which is difficult to compare with
Page 140 and 141: eason why some invertebrates showed
Page 142 and 143: This study did not set out to expli
Page 144 and 145: This reliance upon the early establ
Page 146 and 147: CHAPTER 6 INITIAL COLONISATION OF D
Page 148 and 149: esulting community at any stage of
Page 152 and 153: emoved since they were the only tax
Page 154 and 155: All statistics were performed using
Page 156 and 157: RESULTS Univariate analysis of spec
Page 158 and 159: 3.5 3 5 2 11 5 1 0.5 0 40 35 Ca 30
Page 160 and 161: of non-patch areas (Figure 6.3(vi))
Page 162 and 163: the individuals colonising patch az
Page 164 and 165: Multivariate analysis of community
Page 166 and 167: Month Sample statistic (Global R) N
Page 168 and 169: 2NP 3NP 4NP .•,, 6NP 5NP 6P 1NP i
Page 170 and 171: Figure 6.8: Two-dimensional MDS ord
Page 172 and 173: - - 5P ... 4P . 6P • .‘2NP 1NP
Page 174 and 175: I 50. 1 60. 70. 80. 90. 100. BRAY-C
Page 176 and 177: 'P2-AZ P3-AZ N2-AZ .- - - " .„ ..
Page 178 and 179: o • o -o + 350 — 300 = 250 7 g
Page 180 and 181: The importance of the ambient commu
Page 182 and 183: In April, when P. elegans larval av
Page 184 and 185: not only for errant polychaetes, bu
Page 186 and 187: observed in this study. How crucial
Page 188 and 189: Micro-scale spatial patterns of mac
Page 190 and 191: METHODS Experimental design - A pre
Page 192 and 193: study. These individuals would not
Page 194 and 195: RESULTS Pilot survey - The pilot su
Page 196 and 197: Transect survey - Micro-scale patte
Page 198 and 199: 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
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CHAPTER 8 THE FAUNAL COMMUNITIES OF
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Other theories have been postulated
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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
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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
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distribution at the micro-scale. Ad
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provide a rich food source for deme
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Armonies W., 1988. Active emergence
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Cha M.W., in prep. Macroalgal mats
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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
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Levin L.A. and Creed E.L., 1986. Ef
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Mileikovsky S.A., 1971. Types of la
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Ong B. and Krishnan S., 1995. Chang
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Raffaelli D.G., Hildrew A.G. and Gi
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Scheltema R.S., 1974. Biological in
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Soulsby P.G., Lowthion D., Houston
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McArdle B.H., Morrisey D., Schneide
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Wharfe J.R., 1977. An ecological su
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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
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ON In co In ° ken n00000N---0g0N-.
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o m000eno,-0-. 0 0000en ,-. 0.-00 o
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APPENDIX 2: SPECIES ABUNDANCES FROM
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0.- CV N - , .- CI E.104 ..r cv g.,
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cv en 0 a .- ,- .- .- g c', ,- ,- g
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PI — — — Pi n — — - R., .
Page 308 and 309:
P . en .2 Co in ,.. ne .- cq . -- -
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