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abundance are highly seasonal, were adapted to large-scale disturbances such as those caused by a severe storm. This study has demonstrated that the P. elegans population on Drum Sands possesses the latter reproductive strategy. Levin (1984a) suggested that species adapted to large-scale disturbances were able to successfully colonise and dominate in areas where the timing of the disturbance coincided with periods of peak larval availability. The two peak periods of larval settlement at Drum Sands occurred during May and December coinciding with the most probable timings of macroalgal mat formation, and sediment movement by storms, respectively. If P. elegans larvae settle and metamorphose more successfully than other species in areas where these types of disturbances occur, then weed mat development and sediment movement are perhaps positive structuring forces in population maintenance. The effects of both artificially-implanted and natural weed mats on adult densities and larval recruitment, and colonisation of disturbed areas are discussed in Chapters 4, 5 and 6 respectively. With the absence of both asexual reproduction and the production of benthic larvae, maintenance of P. elegans's spatial heterogeneity described in Chapter 2 must have involved either increased larval recruitment or adult migration to established high- density patches, or increased juvenile survival within them. Larval recruitment to patch and non-patch azoic and ambient sediments are compared in Chapters 6 and 8 respectively. In Chapter 6, the extent to which adult migration may have been influential in patch maintenance is also discussed. This study has indicated that P. elegans on Drum Sands exclusively relied upon sexual reproduction for population maintenance. Schlotzer-Schrehardt (1987; 1991) suggested that P. elegans was the only reported spionid species in which direct spermatophore transfer is used during sexual reproduction. While other species indirectly transfer their free-floating spermatophores, a special pattern of reproductive behaviour including active seeking of the females tubes by the males is needed for spermatophore transfer. This has implications for both the population's reproductive potential and the micro-scale patterns of P. elegans. The latter will be addressed in Chapter 7. 81
This study has shown that, using relatively simple methods of sex determination, sexual activity and size measurements, a good understanding of the reproductive mode of development and population structure can be gained for a common intertidal polychaete. The results have shown that an understanding of both the mode and timing of reproduction can help elucidate which processes potentially structure a population and hence is an important prerequisite in an investigation into the factors affecting a species spatial (and perhaps temporal) distribution. 82
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%
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 72 and 73: exhibited by the tube-building poly
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 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
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
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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
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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
Page 294 and 295:
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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