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Jone~. N. V. The sheathbill. Chioni.l a/ha (Gmelin). at Signy bland.
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Noble. J.C., Gordon.
w:r.
& Kleinig. C.R. The influence of earth\\Orm~ on the de\elopment of mat~ of org:1nic ma11er under irrigated pasture in ~outhern Australia. Proc., XI /111. Gmssld.Conxr .. 465-..U.S, 1970.
Odum, E. P. Ftmdamenta/.1· of Emlo!fy. Philadelphia, Saundcrs. 1971.
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M. \:111 Zinderen Bakker Sr .. J.M. Winterbottom, & R.A. D)Cr, 16-31. Cape Town. A.A. Balkema. 1971.Smith, V.R. Standing crop and nutrient status of Marion Island ('>ub-Antarctic) vegetation. J. S. Afr. Bot., 42. 231-263, J 976a.
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Smith, V.R. The eflecl of burrowing species of l'roccllariidae on the nutrient status of inl'ind tus~oek grassland-. on Marion Island.
J. S. Afr. Bot .. 42. 265-272. 1976b.
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1970.
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z.
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Wicncr, J. & Glo\1aci~~J..i. Z. Energy flO\\ through a bird com- munit} in a dcciduou' forc~t in southern Poland. Condor. 77.
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Woo<l, T.G. The distribution of earthworm~ (Mcgascolccidac) in relalion to soils. vegetation and altitude on the slopes of Mt.
Ko-;ciusko, Australia. J. llnim. £col., 43, 87-106, 1974.
Cephalopod prey of the sooty albatro sses Phoebetria fu s ca
and P. palpebrata at Mari on Island
A. Berruti a nd T . H arcus P ercy rit zPat ri ck Institute of African Ornithology, U ni ve rsity of Cape T ow n, R ondcbosch 7700.
711l' sooty alhatross Phocbclria fusca alf(/ light-mal/lied sooty alha1ross P. palpebntta are large~P allopatric in rfteir hreeding and pelagic ranges. hul hreed symparrically at i\Jlarion Island. Re[!llfl!itated l'l'-lt\
ol
(ood remains (mainly cepftalopod hea/,s) were analysedw
(Hsc•ss differences in rite foods o( these two species at M01·ion /:,land. Lower beak!. of C<•plwlopods were identified ro species, a11d rite masses of •droll! animals 11·ere estimated. Tlrirfy-se••en ceplwlopod srNcies wen· identified /i'om J 295 heaks derh·ed jro1rr hotlr alha!ro.l·ses. Tire meane~rinrmed ceplwlopod prey mass (2/9 g ami 2<J5 g (or P.
fusca nnd P. palpebrata l'l''flc>Ctire/y) u·as high. a~ dige~tiun
tc:nds to eliminate .\1/mller, less resistant hea/,s. Kondakovia
longimana II'GS tiiC• mo.\·f important speciev h.l' mass. rt/1(1
rite• Onycfwletlllridae. Crancltiidae and Hisriofc•ru!tidae rlre
11111.11 important lamilic•1 in rite /ood of hotlt vpecies. Most ceplwlopod prey ~pede\ were bio/uminl'.\C£'1/f. hut non-bio- /uminesce/11 ceplwlopod1· con.Hituted a ltir.:fta proportion hy ma.1s. Remains o( (ts!r, hird1· and cmswcetms were prese/11 in small amounts. DUJ(•rellces in species composition and mass o(
replwlopod prey between 1fte two alhatrusse.\ H'ere small. and partitioning offoocl reMlurces hy spatial separation o/'.f(•edinl!
area.\ is apparent~l' more si.lfnificanf in tfte segregation of P. fusca and P. palpebrata at J\larion !.1land.
100 S Afr T Anti.lrkt Nov., Dcc1 8 Hl78
I able I
Ccphalopoda, Identified from beak:. found 111 rcgurgu:.ned ca-.h of Plwehl'lria ju1m at '\larion bland. Man.:h-Ma) 197~. Bcal.. mca-.urc- ment~ and rna,~ e,timauon fo11o" Clarke ( 1962). Importance of fam1l~ i, found h:- ~umrning the product.. uf the number' muluphcd
1:>) mean ma-... of all -,pcc1e' \\llhin each famil). and "prc~sed as a percentage of the total ~LII11.
Beal.. measurement (mm) F"inwted ma-.. (gl Import a nee
Order 1-amil~ Sf)ecb - - - of famil>
No. Mean Range 11 1\'lcan Range ('',.)
-
-
Octopoda
Alloposidae 2
Allopo:.m molli.1 :!
Tcutho1dca
Ommastrephidac -1
\ alotodartH 'P· •I 5,X .\1- (,,,,
""
3~·1:!..J() -110
( ln)chotcuthidac 11·1 70
\/ororewhi~ int:!en~ 1) 9.X ~.9-10.0 9 1603 1:!50 17~0
'\larorew/ti, /..niporill f1i l.\9 (>.(o 1.-1- !<.1 75 ..J!<X 160 'J4()
\/or01el/lhis ruhsuni 6 7.J C..J- X,l 6 707 -l..J() 940
Unde~cnb..:d genu~ uml 'I'I<:CIC'> •I
J..mulakm·ia hm[!immw 156 10.5 ·U-14.6 l)(, IX50 140 5-100
(rOIJatidac J')
Gtmtllu' tmlllrctiu" .17 5,5 4.6- 6.(1 29 97 71 120
Gonatu.1 phnehenim• 2
P,)chroteuthidae 11
p, rchrote/1/hi\ xlaciali.l ') 5.6 '.6- 7.0 15 l()() 17'
c. so
Pwdu·oreuthi1 ~p. B :! '.:! .1.2 I 6..1 (,\
rnoplotcuthidac :!
lnci1frocheir111 le~ueuri 1 7.1 6,0- H,2 2 65 11' 215
Oclopotculhidae 4
Oelopoteuthi., sp. ·1 9,5 8,2-11.2 4 278 195 400
lli~tioteuthidae X09 8
11 istioteuthis atlamica 5
lH
J.2- 5.~ 5 107 62 175Hi11iofeuthis dofleini I
Histioteutltis eluminae 715 2.X 1.9- 3.5 90 4~ 21 7J
J-lislitl/elllhi., macrohi,,w 9 4.4 J,}- 5.4 5 124 66 11\5
Hi.,tioteuthis me/eagrmeuthi' (I') 4.7 2.9- 6.9 :!5 14(• 'iO 2!JO
If i 11 iofel/l hi~ mirwula l)
1/i,tioreulfli, ~p. I 2.X :!.8 I ..J(l 4(1
(.'h•rolculh•dac 9'i 2
Chiroteuthi' IIIIII'I'IJ.I/11/111 21 6.2 5.4- 6.9 16 24.-1 165 1.\0
Clumtemhi' piueti 2.\ 4.2 2.0- 6.0 15 90 10 :!20
Chirolelllhi\ -;p, l 49
.u
J.8- 5.1 44 X9 62 14)Chiroremhi' rermni 2 4.5 4.5- 4.6 2 102 I()() IO'i
\la~ugotclllhldae
\ltl\li~:atemhi' 'P· ('
(}clotcuthidac 2
Crdmemhi.' .,enl!lui I 10.4 10.4 I -1.10
.no
Dr,c·mewhi., sp I 11.0 11.0 I 'i20 520
Cranchiidae 1401 \9
raonius be/one I 6,0 6,0 I 170 170
Taonius cymoct,lpll.l 21 8.1 6 .. '\- 9.3 21 .\51 190- 460
I aoniu.'i pa•·n '11 .\2 4,3- 5.8 30 12.5 ~0 160
I eut!1nH·enia megaloJ" i111pc 111111 I 1.7
.u
I 96 96/eurh;rwenia (111/llll'fha llli·l 1.2 .\5- 6,0 90 74 Stl 170
(,a/ireutfnl armma I ~.X 2.X I Jll 10
(lalit<'uthi.l !dacia/i.\ 1:>7 1.~ '1.7- 7.1 71 ')') 56 21)0
,I IC'flll,l'dwteulhil l111111ilr.111i 4 '),-1 x.o-1o,x 2 4li5 .\30 (,4()
/Jwlwtlrauma /yromma I 5.2 5.2 I 12J 123
Ncoteuth idae
Alluroremflis antarclims
Umdenlilied 4
s
Afr. J Antarct Res, Vol. 8 .. 1978 101Table 2
CephaiQroda, identified from beak!, found 111 regurgi1:11ed ca,ls of Plwehetria palpehrata a1 Manon lslan,l March-i'.ht) 1975. Beak measurements and mns~ cstim•ltion fllllo" Cl:trke ( 1962). lmponancc of family i~ found by ~umming th..: prQduch of the number~
multiplied b) mean mas, of all 'pede;. '' ithin each famil~. and e'pre:.~cd a;. a percentage of 1h..: tmal 'um.
Rea\.. me.'hur..:mcnt (mm) I qimated
m"''
(g) lmpurtan<:c Order I amil~ Sj)lx:ie,Nll. :>.-h::lll TctHhoilh:a
On)dWtcuthidac 7'11.
\Jorotewhi1 /..11ipmitc hi :!(• 5.X
Kmulak01 iu ltmgiuumu 52 I) ,-l
Gwwtitla<• X
GOII(I/1/\ 111//III'CliCII.\ )\ 'i.~
P~ychrotcuthidac IX
Psychrotellthi' glue iuli1 17 6.0 Psychrote11thi• '~"· B
OctOpotcu thid:1e
Tauim:iu danue I 4.0
11 istioteuthidae 10-l
Hi.l'lioleuthil elrauinoe 102 2.7
1 /i.1tiotewhi 1 melea.t:roteutfri, I _\.()
If i.llilllelllhi' 111irwu/u I +.X
< 'hirotcuthiuae I I
Chirott•lltfli, IIIU< ro1onu< 7 S.7
Chimii'JIIhi.l fliCieti (I 2.7
~l;htlg;lleuthidae
,\ laltit:oll'lllhll 'P· <.. I ~. 'i
( ranchiidnc ll-:7
Tao11i111 t')'llltWIIflll' 2 7,2
Tooll/11\ pal'o :! -1,9
Tetlillllll'l'llill un/arctiul 105 -1.2
(t~lfiu•uthi., gladuli, 711 5.1
,\-1 t',\ llll_l'du 1/l'll/ lli.1 humi I 11>111 :!
Ncmcuthidac
11/woteutlll\ 1111/arctl< 111 I J,O
r ntroduction
The -,ooty ulbatro-,,. Plweherria {u.w·a. and the light-mantled sooty albatross. P. pa/pehrma. are similar in si~:e (Ben·uti. i.n
pre.,~) and color,llion ((\lx. 1976). Plroeherria {ll>m ha:- a pclagic ntnge bet\\CCn 50 Sand JO Sin the Atlantic ami Indian Ocean~. and breeds on island' between 37 S and 47 S.
P/uw/)('Tria palpehmta ha-, a circumpnlar pelagic range be- tween 40 Sand 60 S. and breed~ on islands between 46 Sand 54 Sin the Atlantic and Indian Ocean'. and in the Au~tral
asian region (Wahon, 1975). I he tw(l 'pecic~ arc largely allopatric in di\lribution. but breed ~ympatrically at the Prince Edward and ('n)lct island-. <Wahon. 1975) and prob- ably al~o at Kerguelen Island (Pa~cal. 1978). The food of the t\\0 '>IJ<!CiC'o \\a~ in1estig:Hed a' part Vf a general 'oiUd) of their co-c'i,tenc.: at t\ 1 arion hland ( Rcrrut i. 1977 ).
Methods
The ir11e,tigation depended on the analysis
o r
regurgitated cast-. of food remain~. Fre,h regurgitated ca~h ''ere collected monthly at nest sites of P. /usca and P. f/11/pehmta on Mnrion Island (46 54'S. J7 45 1-) from October 1974 to \la) 1975.fhe casts Cl)nsi~ted largcly, or entirely, of the beaks and '>permtuophores or ccphalopod-;. Only the cephalopod re- main-, were anal) ~ed in detnil. and the re$ulh reported here are hased on ~amrle\ ol'lwined fr11111 March to May 1975.
fhe lo,,er hea\.., of cephalopod' ''ere ~ortcJ in tu t) pc,.
-..ub~cquemly identified hy Dr M . .1. lmher (Wildlife Ser\'ic.:e..,,
of farmh
Range 11 Mean R:111gc (.,41)
7J 4.~- 7 .. ' IX -110 :!IS 670
6.1-1.~.2 Jl 1490 J90 .IXOO
'\,(}.. 6,7 7 115 X-l 150
6
J,l\- 7.6 14 400 175 IilO
4.0 I '20 120
4
2.1- .>.5 95 -17 26 73
J.O I 5-l 54
-I,X I 1-15 145
'i,:i t'l.'i
'
201 175 :!721.2-·U 5 I-I 10 7-1
'-"
I 170 17016
6.X- 7,6 2 :!(!() 220 lJO
-l,!i- 5.0 2 110 105 115
1,1 5.0 );..j 7(, _l(, 115
I.X- 5. 7 6'i 11 (I (,() 1-10
J.O I t)() (,()
D~partm~nt of Internal AO'airs. New Zealand). The ro~tral length of the IO\\cr beak \Ht'o mea:.ured to an accurac) of O.J mm. using divider~ and n ~tcel rule. Thirty r•tndomly chosen beaks of cac:1 -;pecies were measured in each monthly :>ample containiolg more than JO beak~ of that specie~. Badl) broken beaks were not measured. Particular diOkulty wa~
e\J'lCrienced in de:1ling \\ ith beaks of Ao/1(/a/..ol'ia /ongimana.
in \~hid1 the ·shoulder· and ·wing· of <>mall beaks were ol'ten bro!<c.l above ihc jaw angle. 1-'or thi~ specie,, lo"er ro,tral lengths ''ere estimated from a rcpre\cntati\e 'ample of small.
bmken beaks.
( ephalopod ma"
''a'
c'timated from regre,<;ion, of lo\\Cr ro~tntl length ag:1in~t ma"'· a~ developed for ~eran1te cephalo- pnd familic~ by ('larl-.c ( 196:!). C\CCpt ft1r member-, of the P-;ychroteuthidae. C)clnteuthidae. l'-.cotcuthidae and \la,ti- gntcuthidae. whn~e mas' was C.'>timatcd fr0m the regrc:-.~ion of h)\\er rthtral length again~t mas' fur all ocgop-.id familic, (( larke. 1962) .... ince ~cparatc regres-.ion~ \\ere not available for thc~c familic'Results
Total' of :! 78l) and -Ill lo\\cr hc:th 1)f ccphalop(1;b, of .17 specie~. wen:: identified in the ca~ts nf f. /11.\l'o and P. pa/pt'- hraw re,pccthel) (Table., I and:!).Thirt)·Se\enand IX~pecic'
were identified for P./it.\('0 anti P. pa/j)t'hmla rc~pec1ivcly. All -.p-:d.:~ C\Cept one ( 11/up.l'itll nwlli1 Octopoda) hcl,mg 111 the O..:gon-,ida, the p.::lagic ~qui1h. Only ten -.pccic' Cl)lltri-
102
buted to more than I o o of the beaks obtained from either P. jitsca or P. pa{pehrata (Table 3). Kondako1•ia fongimfma contributed 48 ~. and 64 "" of the cephalopod prey mass taken by P. jitsca and P. pafpelmtta respectively. This was calculated by multiplying the estimated mean mass of each cephalopod species by the total number of beaks or that species and dividing by the estimated total mass of cephalo·
pods eaten, and then expressed a~ a percentage. The most important families by mas!.. and in decreasing order of im·
ponance for both sooty albatrosse~. \\ere the Onychoteuthidae and Cranchiidae. The mean mass per individual cephalopod prey was estimated at 219 g and 295 g for P. fusca and P.
palpehraw. respectively. The largest cephalopods taken by both kinds of birds were K. longimana of 5 400 g and J 800 g.
The mean masses of P . ./itsca and P. palpehrara respecti.vcly arc 2 512 g and 2 823 g (Berruti, in press). Sooty albatrosses presumably ingest only portions of very large cephalopods which are probably taken when moribund or dead, as sug- gcl>ted for other seabird~ which fed on squid (Ashmole &
Ashmole. 1967; lmbcr. 1973).
At least 80 "o and 71 • o of the ccphalopods taken respec- tively by P. jitsca and P. pafpehrara are bioluminescent (Filippo\a. 1972: Imber, 1976; Roelcveld. pers. comm.).
However. nonbioluminesccnt cephalopods contributed at least 61:! "o and 79 o o of the total cephalopod mass taken by P. {11:;cct and P. palpebra/a respectively, as the rcl<ttivcly large-bodied K. longima11a and Momreutltis knipOI'itclti arc non-bio luminescent.
Both sooty albatrosses at Marion Island also fed on fish, birds and crustaceans in small amounL~.
D iscu ssion
The process
ofdigestion in the
stomachs ofseabirds tends to
eliminate relatively less resistant small and immature cephalo- pod beaks. For instance, lmber ( 1973) found that Spimla spirula (estimated mean mass 10 g) constituted 25 "o of the 'lomach conLents of great-winged petrels Pterodro111a tl/acrop·
/era. but only 0,3 • o of the beaks found in regurgitated casts. lmbcr suggested that cast formation begins when ~~
!>ingle large p<tir of beaks. too large to pass through the bird's
Table 3
Abundance and e~timated mean ma~~ of cephalopod sp..-cic">, contributing at lea~t one per cent uf all ccphalopod beak, in the regurgitated casts. uf Plu~t•hetria /11\1'11 or P. palpehraw at Marion
hland. March-Ma) 1975.
/'. )IISCII P. po/pchmlll Specie' No. ol' M:hs No. of Mn ... .,
heal..~ beak.,
( ".,) (g) ( 0 ol (g)
\/m·orewltiJ /..uipm·iu·hi 9 488 (l 410 Kmula/..oria lougimana 6 I 850 IJ I 490
Gouaflts mlfarcricll.\ I 97 2 115
P.l)'< hrore11rhi.\ g/acia/i.1 I
JOO
4 4001/i.llioreurhis elwniuae :!6 48 25 47
/lislioreur!ti.l me/eagrotemhis 2 146 I 54
Cltirore11tftis 1/WcroJoma I 244 2 201
Clliroleutltis picleti I 90 I J4
C!tiroteurhis IfJ. £ 2 89 0
Taoniu.1 pm·o I 125 I 110
J'ellfht"fl'tlia amarctica 42 74 26 76
Calileuthis )!iaciafis 6 99 18 116
S. Afr. T. Antarkt. Nav .. Deel 8. 1978
ginard. is ingested. Both factors should result in an over·
estimation of the importance of the larger cephalopods in the diets of scabirds. Further, Clarke ( 1962) warned that the mass versus rostral length regressions for each cephalopod family may be markedly din·crcnt for diflerent species within each family. The estimates of mean mass per individual cephalopod prey (.219 g for P. (usca and 295 g for P. palpehraw) arc probabl)' on the high side. If either P. jusca or P. palpehrara takes proportionately more small squid. diftcrcntial digestion would mask this difference. The greater number of species appHrently taken by P. /itrca might be explained entirely by the relatively large sample of beaks available for this species.
Evidence for scavenging is provided by the occurrence of feathers of rockhopper penguins £1/(lypres chrysocome in the food remains of P. {ttsca and P. palpebra/a, and feathers of macaroni penguins £. chrysoloph11s in the food remains of P. /itsca (Ben·uti, 1977). it is unlikely that sooty albatrosses kill live. healthy penguins.
Cephalopods were the most frequently found items in the
~tomach contents of P. /mea and P. pafpehrara at the Crozet islands (Mougin. 1970) and constitute the most important food of four other species of albatross: Diomedea chryso.l·roma (Tickell, 1964). D. melanopltri.1 (Tickell. 1964). D. irromra (Harris, 1973) and D. exulans (lmber & Russ. 1975). lt appears that there is a considerable overlap in the species composition and size or the ccphalopod diets of P . . {ttsca and P. pa/pebrara at Marion Island. Methods or prey capture and detection are not known. Both P. fusca and P. palpehra/a probably obtain most of their food at night, when cephalopods migrate vertically to the surface of the sea (lmbcr. 1973).
Al>hmolc ( 1968) suggested that surface-feeding sea birds will catch any suitably-siLed prey on the sea surface. and arc essentially non-selective '' ith respect to the taxonomic aflinities of their prey. Thus. the diA'erences in species com·
position and size of cephalopods taken by the two sooty albatrosses may merely reflect relative availability of cephalo·
pods in difl'erent feeding %Ones.
1'/toeherria jitsca and P. pafpebraltt breed at approximately the same time of year (13erruti. in press). Competition be- tween these two species for nest sites at Marion Island does not appear to be significant, and breeding adults of the two populations have spatially separated feeding areas with /~.
/it~ca feeding primarily to the north of the Antarctic Con·
'ergence. and P. palpchraw to the :.outh ( Berruti, in pre!>S).
Thi~ ecological diAerence doe~ not necessarily indicate that there was. or is. competitive exclusion between the two species. but it may now be of importance in allowing the two populations to co-exi~t at Marion Island.
AckiiO\I'Icdg('ments
We thank Dr M.J. lmbcr for identifying the specimens on which this paper is based and Martina Roeleveld for helpful advice. Biological \\Ofk on Marion Island is supported linancially and logistically by the Antarctic Division of the South African Department of Transport. A.B. acknowledge~
financial support of the Council for Scientific and Industrial
Re~earch. The work formed part of a programme of research sponsored by the South African Scientific Committee for Antarctic Research.
Rcfcrcncrs
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~cabirds of a tropical oee:tnic bland. Bull. Peahod,1· M11s. 11111.
1/isr .. U. 1-131. 1967.
A'>hmole, N.P. Bod) ~ize, prC) ~i/e. and ecological ~egregation in
S. Afr.
J.
Antarct. Res., Vol. 8., 1978fh·e ~ympatric tropical terns (A\CS: Laridac). Sys. Zoo/., 17, 292-304, 1968.
Berruti. A. Co-existencr in tltl' P/ll)('hetria a/batro.IS!'., at Alurion Island. Unpublished MS<.:thcsb. Uni,ersit~ ofCapcT0\\11. 1977.
Berruti. A. The breeding biologic~ of the Soot) Albatms-.e, Plwr- berria ju.1·ca and P. palpebratu. f.-mu (in preo;s).
C1arkc, M.R. The identification of cepha1opod beaks and the relation<:hip bel\1ccn beak si<:e and total weight. Bull. Brit. i\/111".
nat. lli.11. (Zoo/.). 8. 419-480. 1962.
Co:-., J.B. A re' ie" of the Procellariiformes occurring in South Australian waters. S. Au.wr. Om., 27, 28-82, 1976.
Filippov<J, J.A. New data on the ~quids (Cephalopoda: Oegop .• icla) from the Scotia Sea (Antarctic). /1./u/aco/ogia, 11, 391-406. 1972.
Harri~. M.l'. The biology of the wa,ed Albatross !Diomelleu irromra) of Hood h .. Galapago~. //li1·. IJS. 483-576. 1973.
lmber. M .J. The food of grey-faced rctrels (Ptrrodroma macropfem gouldi (Hutton)), with special reference to diurnal migration of
103
their prey. J. Anim. £col.. -'2. 645-662, 1973.
lmber. M.J. Comparison of the prey of black Pmcrl/aria petrels of New Zealand. N.Z. J. Mar. Fre.lith'ltt. Res .. IU. 119-130. 1976.
lmber. M.J. & RU\\, R. Some food-; of the Wandering Albatro .• ~.
\owmi>, 22, 27-36. 1975.
Mougin, J.L. Le, Albatross Fuligneaux Pluwlll'tria palpehmm et P. }itsca de l'ilc de la Posse,,inn (Archpcl. Crot.et). CNFRA, EcologiC> des Oi,cau' Anlarctiquc~. 1970.
Pascal, M. Note !.ur Plwebnria /tt.H·a. Diomedea dtloror!tyndws, et Dionwdea cltr.t'Jo.\lll/1/a aux ilc\ Kerguelen (49 S, 69 F). Oi~emt,
48.69-71. 1978.
Ti<.:kcll, W.L.N. h:eding preferences of the albatrosses Diomedea melmwpltris and D. cftryso:Jtoma m Bird Island. South Georgia.
In IJio/ogie AnltlrflicJIII!. edited b) R. Carrick. M.W. Holdgatc &
J. Prc,ost. 383-387. Paris. Hermann. 1964.
'vVatM)Il, G.E. Bird!. of the Amarctic and wh-Anwrctic. Washington, D.C.. American Geophysical Union, 1975.
Standing crop and production es timates of selected M arion Island plant communities
V.R. Smith Institute for Envi ronmen tal Sci ences, Univers ity of th e Orange Free State, Bloemfontein 930 1.
Standing crop and a/uJI'e-growul standing hiomass increa.'it!S durin}J the• ;:rowtli season are provided for titre'(' plant com- munities on Mm·ion Island (sub-Antarctic). Tlte l'a!ues support prerious ohsermtion1 tltat low-altitude sub-Anwrctic l'egetatiom accumulate• /argr quantities o( ahon•ground plant matter am/
that tltey are JJ/Ore productive titan mosr norrltem ltrmisplwre tundra t'l!lf<'f(ltions.
Introdu ction
Despite recent efforts inspired by the International Biological Programme, little is known regarding the primary production and standing crops of sub-Antarctic 'egetation. Available data to date are confined to Macquarie Island (Jenkin. 1975) and South Georgia l~land (Smith & Walton, 1975). Huntlcy ( 1972) and Smith ( 1976, 1977) provide standing crop value!>
of several lowland plant communities on Marion Island.
Additional information for three of thc:.e communities Cfernbrakc. Amena mage/lanica drainage-line and lu~~ock grassland) on the island's eastern c.:oastal plain is presented in this account. and. preliminary c~timatcs or their annual production are prO\ ided. Comprehensive de:.criptions of the communi tic~ arc pro' ided in Smith ( 1976).
!Vlethods
The slanding crop values shown in Table I are those at the appro,imatc time of maximum abO\C-ground biomass in the growing season and were derived rrom the harvested quadr<ll method described in Smith ( 1976). Primary production w:1s estimated in two ways: (a) as the ditl'erence between peak biomass (living material) and that at the start of the growing season, and (b) the difl'erence between the corresponding standing crop (living and dead material) values.
Results and discu ssion
Biomass and standing crOJlS
Standing crop and produ<.:tion estimates for the three communities arc presented in Table I: so;ne values for l.imilar communities on other sub-Antarctic islands arc also provided.
Only general conclusions can be drawn from compariso11s between the islands since difl'ercnt methods have be::n used and the~e give values ''hich are known to vary. even within the same site (Walton. Grccne & Callaghan. 1975). In addi- tion. biomass varies seasonally. As Holdgatc ( 1977) points oul. there arc two statistical problems in comp:uing available standing crop and productivity c~tim:lles from sub-Antarctic region~. namely the reliability and inter-comp:tr,tbility of the method:.. and the relationship of the sample sites to the localities in which they occur. None of these localities has been studied sutlicicntly well 10 provide data on 1:1e v,tri 1- bility in biomass ami production within them. and m.my of the e~timates are dcri,ed from 'nnll atypical are:1s of ~hcl
tered or highly produ<.:tive veget 11ion.
Mo~t or the available data. however. indicate that large above-ground biomass value:, occur in sub-Antarctic 'egeta- tion. in contra~t to tundra areas of the no:·thern hemisphere with their bitterly cold. continental winters. Large amounts or dead material. predominanlly in the form of standing dead.
accumulate in sub-Antarctic 1egetation and this is renected in the high standing crop figure~ in Table I.
Abo,c-ground biomass and ~landing crop estimates for 1972 and 1974 from the same communities on Marion Island are very similar but the below-ground value:. dirrer b;!twecn the '''o dates. Thi~ is probably in error. since the 1972 below-ground estimates wer.: ba~cd on only 4 samples each.
The 1969 value for the above-ground biomass of fernbrake
