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provide a rich food source for demersal fish. It is likely that all these apply to the P. elegans patches on Drum Sands. In addition, the results presented here suggest that tube-building species have a marked effect on the distributions of many invertebrate species. C. volutator was found to be present almost exclusively within P. elegans patches and, therefore, these tube-beds allow some species to occur on Drum Sands which would otherwise not survive. A change in the population fitness of P. elegans may result in the population fitness of other species. Consequently, elucidating the processes which affect the distributions of tube-building polychaetes (the second aim of this thesis) helps in the understanding of the processes spatially structuring the benthic communities in such areas. This is particularly important in areas where tube- beds occur on large scales, e.g., 150,000m 2 in Barnstable Harbour, Massachusetts (Sanders et al., 1962). For this to be achieved, explicit studies addressing the reasons why many species exhibit significantly higher densities in tube-beds should also be conducted. In conclusion, the approach adopted here of a combination of pattern documentation and manipulative experiments to test hypotheses about the underlying mechanisms is unusual in ecology. Only too often are post hoc explanations proposed to explain patterns without serious attempts to experimentally falsify such hypotheses. In this respect the present thesis makes, I believe, an important contribution to understanding the structure and dynamics of intertidal assemblages. 243
REFERENCES Addicott J.F., Aho J.M., Antolin M.F., Padilla D.K., Richardson J.S. and Soluk D.A., 1987. Ecological neighbourhoods : Scaling environmental patterns. Oikos 49:340-346. Allen T.F.H. and Hoekstra T.W., 1991. The role of heterogeneity in scaling of ecological systems under analysis. In : Ecological heterogeneity. Kolassa J. and Pickett S.T.A.(eds.). Springer-Verlag. New York. Ambrose W.G.Jr., 1984. Role of predatory infauna in structuring marine soft-bottom communities. Mar. Ecol. Prog. Ser. 17:109-115. Andre C. and Rosenberg R., 1991. Adult-larval interactions in the suspension-feeding bivalves Cerastoderma edule and Mya arenaria. Mar. Ecol. Prog. Ser. 71:227-234. Andrew N.L. and Mapstone B.D., 1987. Sampling design and the description of spatial pattern in marine ecology. Oceanogr. Mar. Biol. Ann. Rev. 25:39-90. Angel H.H. and Angel M.V., 1967. Distribution pattern in a marine benthic community. Helgolander wiss. Meeres. 15:445-454. Anger K., 1977. Benthic invertebrates as indicators of organic pollution in the Western Baltic Sea. Int. Revue Ges. Hydrobiol. 62:245-254. Anger K., Anger V. and Hagmeier E., 1986. Laboratory studies on the larval growth of Polydora ligni, Polydora ciliata and Pygospio elegans (Polychaeta, Spionidae). Helgolander Meeres. 40:377-395. Anger V., 1984. Reproduction in Pygospio elegans (Spionidae) in relation to its geographical origin and to environmental conditions: a preliminary report. Fortsch. Zool. 29:45-51. 244
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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
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studies may have been completely di
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METHODS Study site - The exact posi
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1 C N W 4----111" 1.5m 2 NW C Contr
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sediment sampling, together with re
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RESULTS Species abundances - The me
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; 15 35 — 30 — 25 — 10 — 5
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statistical difference from net plo
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Pygospio elegans size distribution
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used, approximately equivalent to t
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artefacts associated with the metho
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present in high numbers around sewa
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lack, hydrogen sulphide-smelling se
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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
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Micro-scale spatial patterns of mac
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METHODS Experimental design - A pre
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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
Page 210 and 211: 1.2 -0.4 "a 0.8 > (i) % Water conte
Page 212 and 213: examine the micro-scale spatial pat
Page 214 and 215: Invertebrate larvae, those of polyc
Page 216 and 217: laboratory observations are needed
Page 218 and 219: CHAPTER 8 THE FAUNAL COMMUNITIES OF
Page 220 and 221: Other theories have been postulated
Page 222 and 223: RESULTS Univariate analysis of spec
Page 224 and 225: -T. g 80 g 50 40 30 20 10 (i) Adult
Page 226 and 227: in significant differences in size
Page 228 and 229: 8.2). This was mainly because of th
Page 230 and 231: 120 100 80 60 - 40 20 0. cn1 c.n (i
Page 232 and 233: 3NP 6NP 4NP 1 NP 5NP 2NP : 3P 1P 6P
Page 234 and 235: 4P 3P 5P 5NP 6P 2P 1P Figure 8.8: T
Page 236 and 237: Figure 8.10 shows the dendrogram pr
Page 238 and 239: NP1 NP2 NP2 NP2 NP1 NP1 NP2 NP2 NP2
Page 240 and 241: Sediment water, organic and silt/cl
Page 242 and 243: 5 350 — 300 250 200 — ISO — 1
Page 244 and 245: abundances of P. ciliata had more d
Page 246 and 247: levels of silt/clay and organics. S
Page 248 and 249: 1973; Noji and Noji, 1991). Competi
Page 250 and 251: shown to consume up to 68% of a 0-g
Page 252 and 253: In Chapter 7 the micro-scale spatia
Page 254 and 255: and positions of patches. Consequen
Page 256 and 257: epresent those found establishing i
Page 258 and 259: distribution at the micro-scale. Ad
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
Page 292 and 293: - 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.,
Page 304 and 305: 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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