A biological study of Durvillaea antarctica (Chamisso) Hariot and D ...

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231 Harvesters will not cut all small pla.nts" Probably only the largest specirnel1s \\li11 be selected, and their removal wU.l have the effect of increasing the gro\'Jth rate of small plants previously shaded in the l.\nderstorey (Pig. 8. fib} . They will not .grow as fast as recolonising plants and for reasons outlined in Chr~pter 9 only a small percentage will survive. No cO'fo.)1\ercia1. harvester is likely to chip away holdfasts exposing the patches of. bare rock beneath. Yet holdfasts cover up to 20% of the toto.l .I':ock surface, and :t:ecolonisation is heaviest on old holdfast sites. If, when harvesting during the fruiting season, holdfasts are left, then a large area of the rock cannot be recolonised. It takes 4-6 months for holdfasts to rot away, so the bare patches of rock are not exposed until summer or autumn, whereupon they are pr~nptly colonised by such opportunistic species such as UZva Zactuea. If harvesting is carried out in summer~ then it is best to leave holdfasts" When they finally rot away the Durvi Uaea would be fruitiing and could recoloni se the bare patches of rock. It is pointless leaving stipes when harvesting. Neither species regenerate new blades from severed stipes, Sometimes D, wiZlana stipes heal over a.nd the la taral blades continue to grow, but in most cases both stipe and holdfast rot away_ Leaving stipes only prolongs the rate of decay of holdfasts, and without their stipes, harvested plants are very difficult to hal1dle. All of the experimentally cleared areas in this study were bounded by virgin stands of kelp. Gametes and zygotes only had to drift a fe\'l metres to recolonise the c'leared sites. The distance that gametes will drift is not known. Presumably sperms drift a long \oJay, but the sacs of ova when discharged from conceptaeles sink quite quickly (3-6 em per minute) and are unlikely to drifC very far. If all fertile plants are harvested from several kilometres of shore then there is no guarantee that ova are dispersed Nidely enough £01: all of the harvested ax:ea to be recolonised. In parts of Chile w·he.'Ce almos 12 0.11 large D, antarctica are ha.rvested for food (Appendix. 5) recolonisation by the kelp is very slow {Pa.ine, pers. comm _} " Ova may onJy drift far enough to recolonise the margins of the harvested area with the resultant recolonisation of the rest of the area taking sevel:al years" Nei ther : time nor resources peL'mi t ted me to harvest several
232 kilometres of shore, or alternatively to harvest an isolated bed of Durvillaea bounded on either side by a long sandy beac~ to record the rate of recolonisation. An eJtpcr im.en t -along these lines should be carried out before any large-scale harvesting begins. In the event that. h
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A BIOLOGICAL STODY OF AN'JlARCTICA
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j i "The seas: CCl1l1(2: running in
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v CHAPlEt( 7 8 9 10 t\ PPE ND ICES
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vii Fot' theil' effol"ts to obi;ain
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CHAPTER INTRODUCTION I acid and its
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1 CHAPTER TWO MATERIALS AND METHODS
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(c) Standing crop Nas measured as w
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7 the primary blade broke off. Furt
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9 four sites: Areas 5b and 6b at 'f
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1 t the rock surface. Area E (1 x 2
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13 ____ ~ __ 2_._2 Scale of concept
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15 added to the top of the tube. Th
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In addition, dai records of sea sta
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19 The series of low ridges absorbs
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Figure 2.1. LOCATION OF PRINCIPAL S
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Figur.e 2.3. TAU'l'UKU STODY AREA.
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T fine cracks D
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'to J ~" FMAMJ ASONDJ ASONDJ FMAMJ
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27 CH/\P A TAXONOMIC AND NOMENCI ..
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29 (i) Hol,dfast The external morph
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31 {c} The basic cellular arrangeme
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3.1 J03 TYPIFICATION (1) DUX'viUaea
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35 commanded on a scie:ntlfic voyag
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37 recently as 1921 (Cockayne 1921)
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stipe (less than 5 em long) and a h
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41 A TeD spccimclI annotated on the
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43 cortex (Figs 3.3a and 3.4e). Oth
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45 and states, "SaY'cophYCU8 simple
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47 holdfast,
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49 Table 3.1 Differences between Du
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51 General distribution: The Chatha
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53 7 ~) (a) Stipitate lateral lamin
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(a) Laminaria po~oidea in the Lamou
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of D. Hook.fil. 1845. TCD .3 in (c)
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LAMINA SECTIONS OF HERBARIUM SPECIM
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=.at.:;;;.;;;:.,;;;;....:....;,., .
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(b) (c) (d) SECTIONS THROUGH THE ME
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II I J c d
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f end of lamina or differentiated m
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66 that DurvilZaea extends several
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613 numerous narrow channels. On th
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70 from IVJLWS to a level between t
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72 within 0,3-0.5 m of the band. Th
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74 Some growing on crevices on the
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76 level of stl/ards of D. ar/"l;ar
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78
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80 algae except for those in crevic
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82 (d) Australia: D. potatoY'UflJ i
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84 d~stribution at species, winter
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86 several thousand miles. It is li
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80 (cl D. antarctica extends no nor
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90 The most southern tip of South A
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92 islands. On Kerguelen and Crozet
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Figure 4.2. D. ANTARCTICA AT HEARD
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d e
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~I 50
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WORLD DISTRIBUTION OF DlIRVILLAl!:A
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Figure 4.6. DISTRIBUTION OF D. ANTA
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50 45 /" b WATER LOSS /0 EXPESSED A
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102 In almost all the composite hol
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104 confined to the merist.oderm, t
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106 longe:r.: than D. anta:.r'ctica
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108 This is not the only way that l
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110 (iii) Cape form (Figs.3.9a,b: 5
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of antarctica across a 9 Sa 8 7 10
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114 'rable 5,3 Measurements of D. a
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116 Subsequent reg~neration of shor
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118 at the entran.ce to l-'Iilford
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120 with increasing latitude. The i
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1mm
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t lOO,AU".
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30-60mins 2
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J I em IDem J ] 10 em ] IOcm 3-4 we
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f
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CJ) -0 I\) Q.. 60 50 Q 3 40 ~ ....
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Figure 5.9. CLIFF FACES AT TADTUKU.
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UNUSUAL STIPE FEATURES OF D. A GROW
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DEGREE OF LAMINA DIVIStON AND HONEY
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Figure 5.14. COMPARISONS OF SAMPLES
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135 CHAPTER SlX REPRODUCTION AND PH
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137 Hyphae invade the neck region o
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'I'he reproductive period of D. wil
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141 A large number of ova at 20°C
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143 released in each of the three s
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Figure 6.1. DEVELOPMENT OF CONCEPTA
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Figure 6.2. REPRODUCTIVE PERIODICIT
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147 CHAPTER SEVEN GROWTH AND MORTAL
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149 (i) Holes punched longitudinall
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4 lSI growth in the length for the
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153 Table 7.5 Frequency of D. antaY
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155 Holdfast diameter increB,sed at
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157 7.5 MORTJ.l.LITY (a) Mortality
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159 seasonal pattern simila~ to tha
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161 A similar of small plants there
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! 6.0~ 5.8 Total 5.6 Ie ngth 5.4 (
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120 100 E E ~ 8 c ~6 ~ +- (I) ..n I
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202 t 1 2 J1cm 3 11 1c
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A Perce:n increase in diameter x lO
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60 Percentage increase 40 in length
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70 60 Percentage increase 40 in len
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il10rease 20 ill rot!)1 length. r '
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mortality 3 .' ' A , ••••
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5 4 Percent mottality:1 per month h
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60 50 2 :3 Plant length (metras) 5
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175 total length closely resembled
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177 sampling error l , and to elimi
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179 of the shoreline; a procedure r
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Figure 8.1. SIZE DISTRIBUTION OF A
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Figure 8.2. size at different seaso
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F i2..ur e 8. 3 • SEASONAL VARIAT
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(a) STORM DAMAGE TO A D. WILLANA BE
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186 clumps of Pachyme~ia ZU8oria, G
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HIB (continued) Species sp. 5P, Zin
Page 247 and 248: 190 On areas cleared during spring
Page 249 and 250: 192 mlportant cause was probably pr
Page 251 and 252: 194 recoLonis of D.anta .. cticc't
Page 253 and 254: 196 (d) Numex~cal density: While st
Page 255 and 256: 198 Although the standing crop of D
Page 257 and 258: 200 however 1 the articulated coral
Page 259 and 260: SUCCESSION ON AREAS CLEARED IN SPRI
Page 261 and 262: Figure 9.2. GROWTH IN LENGTH OF REC
Page 263 and 264: ANTARCTICA: confidence limits. GRCW
Page 265 and 266: Figure 9.5. KAIKOURA. STIPE GROWTH
Page 267 and 268: Figure 9.7. STIPE GROWTH OF RECOLON
Page 269 and 270: Figure 9.9. change in the stipe pro
Page 271 and 272: Figure 9.12. CHAOOE IN S1 ZE DISTRI
Page 273 and 274: Figure 9.13. Growth of ~ua1l « 0.5
Page 275: Figure 9.14. EXPERIMENTAL REMOVAL O
Page 280 and 281: 213 pathway of Du~vittaea sp. ALLOP
Page 282 and 283: 215 'co d:tying conditions than D.
Page 284 and 285: 217 appears to be gl:eatly influenc
Page 286 and 287: 219 tide. From Bayle's Law 1 the bl
Page 288 and 289: 221 buoyancy. A highly honeycombed
Page 290 and 291: 223 of D. antaratiaa across 25° of
Page 292 and 293: 22S Hasegawa (1962) and Kat ... ash
Page 294 and 295: 5 ..· 7 years old. Some were still
Page 296 and 297: 229 . or combinations of species, p
Page 300 and 301: 233 10.10 THE RESOURCE RELATIVE TO
Page 302 and 303: 235 10.11 SUMMARY (1) Four DurviZZa
Page 304 and 305: 237 (17) The mean standing crop of
Page 306: RELATIONSHIP BETWEEN TIME OF HARVES
Page 309 and 310: 241 Batham, E.J, (1965). Rocky shor
Page 311 and 312: 243 DaNson, E. Y. (1966). Marine bo
Page 313 and 314: Hooker, J.D. and Harvey, W.H. (1843
Page 315 and 316: 247 Kuehnemann, O. (1970). Algunas
Page 317 and 318: 249 Moore, L.B. and Cribb, A.S, (19
Page 319 and 320: 251 Skottsberg, c. (1941). Communit
Page 321 and 322: 253 Will. H. (1890). internationaZe
Page 323 and 324: 255 APPENDIX ONE (CONTINUED) (b) DA
Page 325 and 326: 257 APPENDIX TWO DIS'I'RteUTION REC
Page 327 and 328: 259 APPENDI)( THREE DISTRIBUTIONAL
Page 329 and 330: 261 APPFNDIX FOUR DRIFT RECORDS OF
Page 332: 264 (i) Boil the dried kelp in a sa
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A biological study of Durvillaea antarctica (Chamisso) Hariot and D ...

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