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This reliance upon the early establishment of macroalgae and sediment accumulation has been proposed for L. conchilega mound development at Tentsmuir Beach, St. Andrews, by Carey (1987). Carey (1987) suggested that the formation of high-density patches of L. conchilega, together with accumulated sediments, were facilitated by Enteromorpha spp. development and that their survival during winter storms were dependent upon the presence of the weed to enhance spring recruitment of L. conchilega. Similarly, Fager (1964) recognised that increased larval recruitment, allowing worm numbers to build up before periods of high water movement, was a prerequisite for 0. fusiformis patch formation in Mission Bay. The present study on Drum Sands did not give any insight as to the possible reasons why V. subsimplex establishment was spatially heterogeneous. One would have expected that algal mats would most likely establish on P. elegans patches since the hydrodynamic effects of the worm tubes and stabilised sediments (see Chapter 8) encountered there may have facilitated algal spore settlement. However, this was clearly not the case: although macroalgal mats did establish on P. elegans patches many of the patches remained weed-free and weed covered many non-patch sediments. This suggests that algal V. sumbimplex mat development, at least during the year of study, reflected a cause of the observed faunal changes rather than an effect of the ambient faunal assemblages. It could be concluded that V. subsimplex mat formation was determined by other, non-investigated factors. In conclusion, this study has indicated that V. subsimplex, a green filamentous alga with a very different morphology from algal species previously investigated by surveys (Perkins and Abbott, 1972; Nicholls et al., 1981; Wiltse et al., 1981; Reise, 1983a), had an enriching effect on the faunal communities of the intertidal sandflat Drum Sands. It is likely that this effect, which contrasts with those observed in other descriptive surveys (and the controlled algal-implantation experiment in Chapter 4), was due to a relatively low weed biomass although the effect of weed morphology may have also been an important factor. Increased numbers of the most abundant species, P. elegans, was due to increased larval recruitment either via increased settlement and/or increased larval survivorship. This study also indicated that a link 129
etween V. subsimplex mat establishment and the formation of high-density patches of P. elegans in previous years may have been possible. Since weed species, biomass, timing of establishment and patch size are all factors which are likely to change from year to year, extending the results obtained here to a conclusion concerning the long- term role of macroalgal mats on the spatial patterns of the invertebrate fauna on Drum Sands is inherently subjective. Long-term studies are needed to investigate this less equivocally. 130
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
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
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 146 and 147: CHAPTER 6 INITIAL COLONISATION OF D
Page 148 and 149: esulting community at any stage of
Page 150 and 151: ambient sediment had been removed.
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
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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
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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
Page 262 and 263:
Armonies W., 1988. Active emergence
Page 264 and 265:
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
Page 274 and 275:
Levin L.A. and Creed E.L., 1986. Ef
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Mileikovsky S.A., 1971. Types of la
Page 278 and 279:
Ong B. and Krishnan S., 1995. Chang
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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
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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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