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PROCEEDINGS

OF THE

LINNEAN SOCIETY

NEW SOUTH WALES

VOLUME 107 (Nos 469-472, for 1983-84)

Sydney The Linnean Society of New South Wales 1984

Bg 4 ated Ps) SP a Palen wn 1 - 7%. iv Sori ‘

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Contents of Proceedings Volume 107

NUMBER 1 (No. 469) (Issued 21st December, 1983)

SELKIRK, D. R., SELKIRK, P. M. and GRIFFIN, K. Palynological evidence for Holocene environmental change and uplift on Wireless Hill, Macquarie

ROBINSON, K. I. M., GIBBS, P. J., BARCLAY, J. B., and MAY, J. L. Estuarine flora and fauna of Smith’s Lake, New South Wales.................. BACKHOUSE, J. M., and MCKENZIE, K. G. The re-establishment of the ostracod fauna of Llangothlin Lagoon after adrought................ RIMMER, M. A., and MERRICK, J. R. A review of reproduction and development in thefork-tailed cathishes (Anidae)i. 5s... 54..5252-2-5- GRAY, M. R. The male of Progradungula carraiensis Forster and Gray (Araneae: Gradungulidae) with observations on the web and prey capture.........

NUMBER 2 (No. 470) (Issued 21st December, 1983)

WEBBY, B. D. Lower Ordovician arthropod trace fossils from western New SOuUmblaVViale Syes serrata cent cnet ee a tation Rutile ait kc ageless occas ni ae cee ue ou FLANNERY, T., MOUNTAIN, M.-J., and APLIN, K. Quaternary kangaroos (Macropodidae: Marsupialia) from Nombe Rock Shelter, Papua New Guinea, with comments on the nature of megafaunal extinction in the New Ginimeaylnelalam cs es eee see eel aire a. teen ti ei ceo Ce a aa DAWSON, L. The taxonomic status of small fossil wombats (Vombatidae: Marsupialia) from Quaternary deposits, and of related modern wombats. . SOUTHCOTT, R. V. A new Australian species of Charletonia (Acarina: arythiraerGac) enon a sein wi aresito a) tars sueeetel Unter tha ates a rsretha a aha ac.) aaa OSBORNE, R. A. L. Cainozoic stratigraphy at Wellington Caves, New South \NVRIES 75s 5 (sara Beige af ea Reta reer ree relat ee nae arn Gamiarecn csi agnae mace ailale Annexure to Numbers 1 and 2. The Linnean Society of New South Wales. Record of the Annual General Meeting 1982. Reports and balance sheets . Record of the Annual General Meeting 1983. Reports and balance sheets .

41

51

59

NUMBER 3 (No. 471) (Issued 11th December, 1984)

Papers read at the Symposium on the Evolution and Biogeography of Early Vertebrates,

Sydney and Canberra, February 1983

CAMPBELL, K. S. W., and BARWICK, R. E. The choana, maxillae, premaxillae and anterior palatal bones ofearlyidipnoansin sae ee ee ee CHANG MEE-MANN and YU XIAOBO. Structure and phylogenetic significance of Diabolichthys speratus gen. et sp. nov., a new dipnoan-like form from the ower, Devonian ofeasterm: Yunnan: C:liiniaaees eee DINELEY, D> LE, Devonian\vertebrates im biostrationap hiya ener ELLIOTT, D. K. Siluro-Devonian fish biostratigraphy of the Canadian arctic Islands.) | CN als sates ly et Cat amey hy ate a eee e nhs in ete A GOUJET, D. F. Placoderm interrelationships: a new interpretation, with a short review Oljplacoderm classiticatiomsi yg nee ee KEMP, A. A comparison of the developing dentition of Neoceratodus forsteri and GCallorhynchus militeg) 2 ern aie eres eels eet pee ee LONG, J. A. New phyllolepids from Victoria and the relationships of the group. . PAN JIANG. The phylogenetic position of the Eugaleaspida in China.......... RITCHIE, A. A new placoderm, Placolepis gen. nov. (Phyllolepidae), from the ate Devoniantot New South iWalesi sty ese ingen eee a a SCHULTZE, H.-P. The head shield of Yiaraspis subtilis (Gross) |Pisces, Ar- throcima | eed dg Sh dade eyeing ee carey ates aie eee orton a ie SMITH, M. M. Petrodentine in extant and fossil dipnoan dentitions: MICrOstLUctUre, HISto Genesis and Srow thie: eset a eee eee VOROB’EVA, E. I. Some procedural problems in the study of tetrapod origins. . . WANG NIANZHONG. Thelodont, acanthodian, and chondrichthyan fossils from the Lower Deyonianiofsouthwest' Clainaal rs ele ei eee eee YOUNG, G. C. Comments on the phylogeny and biogeography of antiarchs (Devonian placoderm fishes), and the use of fossils in biogeography......

NUMBER 4 (No. 72) (Issued 11th December, 1984)

Moore, K. M. Two new species of Glycaspis (Homoptera: Psylloidea) from tropical @ucensland- waithinotes on thee en usin eee RAJPUT, M. T. M., and CAROLIN, R. C. Phyllotaxis and stem vascularization ot Dampicra Br: (Goodeniaceae) me. ea en ee MORAN, P. J. Variability in the opercular structures of the serpulid polychaete HA ydrovdes elegans (Tlaswell\icrta. coy es oe ee ee LESTER, L. N. Two new chiggers from Australian marsupials (Acari: Trom- Iptculidae): sso. 525° eens ay a Cette eet cs et LAMBERT, D. M., and PATERSON, H. E. H. On ‘bridging the gap between race and species’: the isolation concept and an alternative................. KOTT, P. Related species of Trididemnum in symbiosis with Cyanophyta....... MARTIN, H. A. On the philosophy and methods used to reconstruct Tertiary VESECAON oo oe sass 6 o olag hd. eeetten eee eter Vel

INDEX to Proceedings vol.'1077 3) 205 ee ees ke ds

147

443

PROCEEDINGS ofthe |

LINNEAN SOCIETY

NEW SOUTH WALES.

VOLUME 107 NUMBER 1,MAY/JULY NUMBER 2, AUGUST/NOVEMBER

NATURAL HISTORY IN ALL ITS BRANCHES

THE LINNEAN SOCIETY OF NEW SOUTH WALES

Founded 1874. Incorporated 1884.

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OFFICERS AND COUNCIL 1982-83

President: A. J. T. WRIGHT

Vice-Presidents: HELENE A. MARTIN, A. RITCHIE, F. W. E. ROWE, J: @: WATERHOUSE

Honorary Treasurer: A. RITCHIE

Secretary: BARBARA STODDARD

Council: D. A. ADAMSON, A. E. J. ANDREWS, M. ARCHER, R. A. FACER, L. W. C. FILEWOOD, L. A. S. JOHNSON, HELENE A. MARTIN, P. M. MARTIN, P. MYERSCOUGH, G. R. PHIPPS, A. RITCHIE, F. W. E. ROWE, C. N. SMITHERS, T. G. VALLANCE, J. T. WATERHOUSE, B. D. WEBBY, A. J. T. WRIGHT

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© Linnean Society of New South Wales

Cover motif: | Stigmodera imitator (Coleoptera: Buprestidae), New South Wales and Queensland. Adapted by Len Hay from Proc. Linn. Soc. N.S.W. 55, 1930, plate IV(6).

eae

PROCEEDINGS of the

LINNEAN SOCIETY

NEW SOUTH WALES rey Peay LIBRARY FEB 4 1987 Woods Hole, Mass. _ VOLUME 107

NUMBER 1 May/July

Palynological Evidence for Holocene Environmental Change and Uplift on Wireless

Hill, Macquarie Island

D. R. SELKIRK, P. M. SELKIRK and K. GRIFFIN

SELKIRK, D. R., SELKIRK, P. M., & GRIFFIN, K. Palynological evidence for Holocene environmental change and uplift on Wireless Hill, Macquarie Island. Proc. Linn. Soc. N.S.W. 107 (1), (1982) 1983: 1-17.

Wireless Hill, at the northern end of subantarctic Macquarie Island, has a raised beach on its western edge at an altitude of about 100 m. The beach is overlain by a deposit of organic-rich sands grading upward into peat, the sequence having a basal date of approximately 5500 years BP. Palynological and other microfossil studies have revealed changes in the vegetation on the site, interpreted as indicating changes in the environment of the site rather than reflecting climatic change in the region.

D. R. Selkirk, School of Biological Sciences, University of Sydney, Sydney, Australia 2006, P. M. Selkirk, School of Biological Sciences and Quaternary Research Unit, Macquarie University, North Ryde, Australia, 2113, and K. Griffin, Institutt for Geologi, Universitetet 1 Oslo, P.B. 1047, Blindern, Oslo 3, Norway; manuscript received 14 September 1982, accepted for publication 17 November 1982.

INTRODUCTION

The location of subantarctic Macquarie Island (158°57'E, 54°30'S) makes it.a potentially sensitive recorder of Quaternary climatic and tectonic events. The island, a fault-bounded and cross-faulted block of ocean floor material (Varne and Rubenach, 1972) is a high point on the Macquarie Ridge, the junction of Indian-Australian and Pacific tectonic plates (Summerhayes, 1974). The area is seismically active. The Antarctic Convergence at present lies just south of the island but was north of it 18000 years BP (Hays, 1983). The climate today is hyperoceanic, cool, moist and windy.

The island was glaciated during the last glacial maximum, but the severity of glaciation is debated. The rather limited glaciations postulated by Colhoun and Goede (1974) and Loffler and Sullivan (1980) appear more likely than glaciation by an over- riding ice sheet coming from the west (where there is now no land) as postulated in Mawson (1943). Taylor (1955) accepted the theory of ice-sheet glaciation and considered the island’s present flora as due to long-distance recolonization in post- glacial times. Bunt (1956) claimed to recognize fossil pollen remnants of a pre-glacial flora, differing from the present one, but suggested that some elements of this flora may have survived the glaciation in refugia on a then-larger Macquarie Island. The evidence for Bunt’s conclusions is unclear. More limited glaciations described by recent authors would not have involved elimination of the biota, since substantial refugia would have occurred within the present limits of the island. Presence of similar refugia on South Georgia is suggested by Barrow (1978).

The timing of the island’s emergence above sea level, and the rates of uplift of the island are also matters of uncertainty. McEvey and Vestjens (1973) dated penguin bones in beach deposits. Colhoun and Goede (1973) dated basal peats on marine terraces close to sea level. They assumed immediate peat formation on any area lifted above wave influence to calculate a maximum rate of terrace uplift of 4.5 m/1000 years. Using McEvey and Vestjens’ penguin bone dates, they calculated a minimal rate of 1.5 m/1000 years, and suggested a mid to late Pleistocene emergence of the island. Blake (Mawson, 1943), from observation of wreckage on west coast terraces,

Proc. LINN. Soc. N.S.W. 107 (1), (1982) 1983

2 HOLOCENE ENVIRONMENTAL CHANGE AND UPLIFT

AREA SHOWN IN DETAIL

North Head MACQUARIE

ISLAND

Contours (50m intervals)

Spot height in metres

Vertical face

Seal wallow areas

Collection site

A

Fig. 1. Map showing location of collection site. AC = Aerial Cove; SB = Secluded Beach; A = Collection site of mat of Amblystegium on Doctor’s Track; W = Seal wallow sampled for pollen analysis; R = Razorback Hill.

PROC. LINN. SOc. N.S.W. 107 (1), (1982) 1983

D.R.SELKIRK, P.M. SELKIRK AND K. GRIFFIN 3

suggested that uplift was extremely rapid and probably measurable in the short term. Bunt (1956) had suggested the island dated from early Tertiary or even Mesozoic times. Miocene marine oozes on the island (Quilty e¢ a/., 1973) make this unlikely.

Quaternary studies on Macquarie Island, apart from studies of glacial landforms (Colhoun and Goede, 1974; Loffler and Sullivan, 1980) and lakes (Peterson, 1975) have until recently been few, and there are as yet no clear indications as to whether any substantial vegetational change has occurred during the Holocene. Considerable interest is now being shown in the island’s Holocene history. Selkirk and Selkirk (1983) reported early to mid Holocene '*C dates for organic deposits from a number of sites and have described fossil mosses from two lacustrine deposits (Selkirk and Selkirk, 1982). Salas, Peterson and Scott (in preparation) are making palynological studies of two cores from Scoble Lake, near the northern end of the island. Ledingham and Peterson (in preparation) are studying raised beaches at several localities.

As the only land in a vast area of ocean, Macquarie Island supports huge breeding populations of seals and sea-birds which have a considerable effect on the vegetation over wide areas (Mawson, 1943; Taylor, 1955; Gillham, 1961; Jenkin, 1975). Evidence presented here of animal-modified vegetation preserved in Holocene deposits on top of Wireless Hill, suggests that Wireless Hill, a small fault-bounded segment of the island, appears to have undergone very rapid tectonic uplift at rates 3-4 times greater than the maximum proposed for marine terraces on the main island mass to the south. It therefore seems that uplift of Wireless Hill has been essentially independent of uplift of the island as a whole.

MATERIALS AND METHODS

The site

Samples analysed were collected from an exposure of peat and organic-rich sand on the western edge of Wireless Hill, a steep-sided headland whose flat top is mainly about 100 m azss.l. (Figs 1, 2). The collection site is at the edge of the plateau, very close to the steep western seaward slope. Samples were collected from a face freshly cut into the exposure, the face extending downwards into a pit, at the bottom of which are beach cobbles. These cobbles clearly represent an extension beneath the deposit of the well-preserved raised beach (R. Ledingham, pers. comm.) which is exposed on the slope immediately north of the collection site (Figs 1, 3).

There are several vegetation types on and around Wireless Hill at present. In Aerial Cove (Fig. 1) there is a low-level beach terrace with Poa foliosa tussock and elephant seal wallows. At the base of the cliff behind Aerial Cove, and in sheltered parts of the steep slopes above Secluded Beach there is extensive growth of Stzlbocarpa polaris. Poa foliosa tussock covers most of the slopes of the headland. The top of Wireless Hill is almost flat (Fig. 2) except for one small tarn and a wind-scoured area forming a slight depression at the head of a gully draining from the flat top to the eastern slopes. Poa

foliosa grows over some of the plateau, and Stzlbocarpa polaris occurs in sheltered spots near the slight depression. Most of the plateau surface supports a low herbfield which includes Agrostis magellanica, Festuca contracta, Luzula crinita and scattered piants of Pleurophyllum hooker.

The isolated plateau of Wireless Hill is linked to the main island by a narrow (about 200 m wide) low-lying (mostly about 5 m a.s.1.) isthmus. During their breeding season numerous elephant seals occupy beaches on both sides of the isthmus and have created large wallow areas between the beaches and the ridge of Razorback Hill (Figs 1, 4). These wallow areas carry a mixed Poa foliosa- Poa annua- Cotula plumosa- Callttriche antarctica community with large bare areas (Figs 4, 5).

Proc. LINN. Soc. N.S.W. 107 (1), (1982) 1983

HOLOCENE ENVIRONMENTAL CHANGE AND UPLIFT

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, (1982) 1983

107 (1)

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D. R. SELKIRK, P.M: SELKIRK AND K. GRIFFIN 5

Sample collection and treatment

The profile sampled totals almost 4 m, the top of the profile (0 cm in Fig. 6) being defined as the peat-soil surface under living vegetation at the site. This is very close to 100 m a.s.1. Samples from 0-270 cm were collected in plastic tubes, internal diameter 2.5 cm, pushed horizontally into the freshly exposed face. All other samples were removed with a spatula into plastic bags. Each sample represents about 2 cm vertical extent. Larger samples for 'C dating (vertical extent shown to scale in Fig. 6) were transferred to plastic bags. A peat monolith straddling the 85 cm level was collected.

Each sample was divided into sub-samples for (1) pollen analysis, (2) analysis of the siliceous fraction, (3) total mineral content determination and (4) stratigraphic analysis.

For pollen analysis ca 5 cc of material were boiled in 10% KOH and then acetolysed using standard palynological techniques (Brown, 1960). Almost all pollen preparations required treatment with HF due to the high mineral content of most horizons and the presence of very abundant opal phytoliths, diatom fragments and chrysomonad cysts.

For analysis of the siliceous fraction ca 5 cc of material were boiled sequentially in concentrated hydrochloric, nitric and sulphuric acids, samples being centrifuged between successive acid treatments (Lacey, 1963). Coverslip strews of the siliceous fraction were mounted in Naphrax mounting medium for observation.

Total mineral content of 5 cc samples was determined by oven-drying at 80°C followed by ignition of the samples at 700°C. Qualitative estimates of the relative abundance of biogenic silica were made from strews of the siliceous fraction. No attempt has yet been made to determine quantitatively the ratio of biogenic silica to other mineral matter.

Stratigraphic analysis was carried out using ca 2 cc samples put in a petri dish with water and studied under a dissecting microscope. Identifiable plant remains and other components of the sample were recorded. Detailed analysis of the peat monolith spanning the 85 cm level was carried out in the same way. Results of these microscopic examinations appear in Figs 6, 7.

A subsample at 85 cm was boiled for one hour in concentrated nitric acid and then washed with 5% ammonium hydroxide as a charcoal verification test (Singh et al., 1981). Macroscopic charcoal particles showing cellular structure were dissected from the matrix and studied with a scanning electron microscope.

A comprehensive reference collection of pollen, fruits, seeds and spores of the extant vascular flora was made during the summer of 1979-1980. Reference pollen samples, usually taken from anthers of several different plants of the species, were acetolysed and mounted in glycerine Jelly.

RESULTS OF ANALYSIS

Three main stratigraphic divisions are distinguishable in the profile (Fig. 6). From 0-175 cm thin layers of well-humified peat alternate with layers of sandy peat. A thicker layer of well-humified peat occupies the 175-232 cm zone. Below 232 cm is a predominantly sandy matrix with interbedded layers of peat. The peat layers may well

Fig. 2. Wireless Hill, photographed from the south east, from deck of ship.

Fig. 3. Raised beach at 100 maz.s.]. on western edge of Wireless Hill.

Fig. #4. Southern end of isthmus, from Doctor’s Track. Note elephant seals on beach (arrow) and wallow areas amongst Poa foliosa tussocks, between beach and Razorback Hill and ridge.

Fig. 5. Seal wallow showing associated vegetation. Pf= Poa foliosa, Pa= Poa annua, Cp = Cotula plumosa, Ca = Callitriche antarctica.

Proc. LINN. Soc. N.S.W. 107 (1), (1982) 1983

6 HOLOCENE ENVIRONMENTAL CHANGE AND UPLIFT

WIRELESS HILL, MACQUARIE ISLAND o-— A JL B SUA- 1681 750 : 150 —¢ A A

1 DIVISION | =20% XP 1DIVISION= 2%2P MET ES See Pare era be 1696 = 4 i es ee ee | 24058 SS 105 ——s} 2792 =)

§

4 ad ° o 2° SSS SSS e e @ (=) ° ° ie] = — 1331 « m A — 9352 —————)] — =z o A —157) oa °o m ee Eee 5 — +806 (a EeSSSSSsSSJq =) ° = = CU es SS 3) eo n 7 = 2 B 1259 a z SUA - 1459 ] 029i se. e 1600 - eae ae m 600 ~ 350 ara) a is 3 == “(6 eee | ——— =) e is] é paces —= 3 aye = 48 ——————— e i = — "76 = ——=—} ° —— 1020 [/|—————~35 ————=] 3) — 203 —————————— e SUA -1582 5) — 1230 a © 3820 - 450 —— 1146 i ° — 1203 sat 3 — 1218 |}———_~___,,, L 99 ————— —S—_ a ——————————————— 3 Beta -1387 = oS SSS 5960 - 350 ne = ae eee) aon | SUA - 1527 | 2334 ae °° ° 5580: 260 Li - e@< 1% ¥ 4 Sl araiecrere =. Poaceae im P gaan - Dicotyiedons <= Present 77) iy) a = = = Pa 3 3 A Sandy peat D Sandy matrix with so Fy | B Well-humified peat peat lenses i (D. and P. Selkirk, 1982) C Sandy matrix E Beach cobbles L

Fig. 6. Pollen diagram and stratigraphy of profile.

occur as lenses within the sandy matrix but have not been traced laterally to decide if this is so. From 384-394 cm the mineral matrix contains sand- to gravel-sized rounded balls of peat. The peat balls probably represent erosion of a pre-existing peat and incorporation of its fragments in the matrix. Whether erosion and redeposition occurred in situ or whether the peat balls were carried some distance by wind or water

Proc. LINN. Soc. N.S.W. 107 (1), (1982) 1983

D. R.SELKIRK, P.M. SELKIRK AND K. GRIFFIN 7 WIRELESS HILL, MACQUARIE ISLAND

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PEAT STRATIGRAPHY (K. Griffin, 1982) e 4 e @ 4 =— cc @ ° ° ° ° ° [ }-—— @ C) , L, ° ° e e ° K—— }— ed ' a] > ° =) e — = ° ° ~) 3 4 ° ° ° —_ oO iz je ca e ° ° ° —— LE e =: —— ° ° ° ”) ) e ° ° ° — = e ° ° ° b pale lp © e ° (=) jL. — 2 eB 5 [esate : Bi ® ° e ° Le o S a : eae Te od fy = e e A Powe le a ® a“ ° ° ° ° | e@ -+— ® a e ° ° =) -— = ea 7 ° e e = i -— le ° ° e —_— — je e e ° -— le LL Pp O e e ° fe }— p od ” e e e ets — ° ° pe -— 2 (7) ° s. ° e — a = z = JL i = 5 ° ° canake }— 5 a a Py a = 3 ° e ° z= 3 3 o 3 a 6 5 ie 3 Ei 3 cy ry Ly EE =| ° 3 a © e ° e e e ——— ° e ee 4 ° Ss) e a le t Present e ° ° e is = Common — Abundant es ij 5 undan e E e Very abundant ° e =) — Oo _— e $8 e 3 ——} e ° ° <= +— ® —_——————— e = ee 5 ra B L = g o 5 a o sc > = = 3

suopajAjooip 12439

Fig. 6. (Continued)

is unknown. Wind ablation of peat occurs on the island today during short relatively dry periods (J. Scott, pers. comm.).

Radiocarbon dates shown in Fig. 6 have been calibrated following Klein et al. (1982). Table 1 shows various radiocarbon dates obtained from the profile. There is no evidence in either the stratigraphy or dating of any prolonged hiatus in deposition since

Proc. LINN. Soc. N.S.W. 107 (1), (1982) 1983

8 HOLOCENE ENVIRONMENTAL CHANGE AND UPLIFT

TABLE 1 Depth Code Conventional Radiocarbon Calibrated Age (cm) Number Age (years bp) (years BP, 95% confidence level) 384-394 SUA-1527 4880 + 90 5580 + 260 SUA-1527 HA* 4610 + 100 5300 + 300 358-360 Beta-1387 5140 + 140 5960 + 350 (soluble fraction) 313-315 SUA- 1682 3490 + 210 3820 + 450 206-210 SUA-1459 1600 + 130 1600 + 350 SUA-1459 HA 1300 + 90 1210 + 160 100-105 SUA-1681 760 + 100 750 + 150

*HA = humic acid fraction

the profile began accumulating some 5500 years BP. There is some wash down through the peats of humic acids, as evidenced by the paired dates for insoluble and soluble fractions of SUA-1527 and SUA-1459.

At and below 274 cm there are large numbers of corroded and fragmented grass pollen grains. Only intact grass grains have been included in the pollen sum. In general, dicotyledon pollen appears to have been less susceptible to corrosion. Callitriche pollen, however, appears to corrode fairly rapidly, but remains identifiable even when corrosion is rather severe. No pollen was recoverable from the 110 cm sample. The pollen sum includes all local and exotic pollen grains, but excludes spores.

Results of the pollen analysis are given in Fig. 6. Exotic pollen grains occur throughout the profile, but in very small numbers, never more than 0.3% of the pollen sum. Podocarp grains are the most common exotic type, and there are occasional myrtaceous pollen grains. Several unknown types of exotic pollen were encountered. No attempt has been made to identify them because of the extremely small numbers involved. Fern spores occur even more rarely than exotic pollen. Of the thirteen encountered in a total of some 54000 spores and pollen grains counted, two are referable to Hymenophyllum and two to Grammitis. The rest are monolete spores which could represent Polystichum and/or Blechnum. All four fern genera are represented in the island’s present flora. Spores of Lycopodium also occur rarely, and are present from the base of the profile. Because of the very low frequency of exotic pollen grains, fern and Lycopodium spores, they have not been included in the pollen diagram.

Grass phytoliths make up a significant proportion of the siliceous fraction of all samples. Diatoms and chrysomonad cysts are also common throughout. Diatoms are common on leaves of living Poa foliosa on Macquarie Island, and may well occur on leaves of most plants where conditions remain constantly moist. Chrysomonad cysts have been observed on the base of living Poa foliosa leaves and are common in samples of surface litter.

A survey of the diatoms in the profile (H. Brady, pers. comm.) shows close correspondence between preservation of diatoms and of pollen. At levels in which pollen is poorly preserved, diatoms are too broken for meaningful counts (e.g. 100-160 em, 230-240 cm, 359-375 cm). These correspond with sandy layers in the stratigraphic column. Marine diatoms are present in low frequency (1-11% of the total diatom count) throughout the profile, presumably from wind-blown spray.

One diatom assemblage stands out in startling contrast to those in the rest of the profile. Pinnularia atwoodi is present throughout the profile in low. frequency (0-4%) but at 394 cm, 344 cm and 294 cm, dominates the assemblage (12-19%). When

PROc. LINN. SOc. N.S.W. 107 (1), (1982) 1983

D. R.SELKIRK, P.M. SELKIRK AND K. GRIFFIN 9

PEAT STRATIGRAPHY (K. Griffin, 1982)

77 A ii io oO = 80 5 s [ ¢ ® o n oe s = S 3 LEGEND | 3 Very abundant 3 85 2 a 89 3 Abundant a = Sa Reed = = = “__ Common Present

jeooseyy

pues sau

snjiijap auly $}3|}001/s}00y Siwiapida/saiqiy surewas jebuny

Fig. 7. Detailed stratigraphy of profile straddling charcoal layer at 85 cm. F =charcoal-rich layer. Other symbols as in Fig. 6.

samples from five modern seal wallows were examined it was found that in all five, there is only a small (less than 1%) marine component. In three of the five, P. atwoodi is common, suggesting that this species thrives in a well-manured environment, such as seal and/or penguin-disturbed sites.

Plant macrofossils referable to specific genera occur most commonly in the well- humified peat layers above 200 cm. Stilbocarpa seeds first appear once pollen of that genus has reached its peak, but reappear throughout the upper part of the profile, even though St/bocarpa pollen percentage declines.

Especially interesting is the occurrence in this profile from a hyperoceanic subantarctic island of two charcoal layers. There is a very distinct charcoal layer at 85 cm, and a less distinct charcoal layer at 30 cm. The layer at 85 cm has been traced a short distance laterally from the sampling site, but its full extent is unknown. A detailed

Fig. 8. Scanning electron micrograph of charcoal fragment from 85 cm depth. Note distinct layering of cell walls in cross-section. Scale line 25um.

Fig. 9. Callitriche antarctica growing as an aquatic in an abandoned or little-used seal wallow.

Proc. LINN. Soc. N.S.W. 107 (1), (1982) 1983

10 HOLOCENE ENVIRONMENTAL CHANGE AND UPLIFT

stratigraphic study of the peat straddling the 85 cm zone is shown in Fig. 7. Movement of charcoal particles up and down the profile from the main layer is probably due to bioturbation. A test used to verify the presence of charcoal in palynological preparations (Singh et al., 1981) indicates that the small black particles seen in the pollen preparations, and the macroscopic pieces visible in the peat, are indeed charcoal. The material even withstands the acid digestion technique used to prepare the siliceous fraction of samples for study. Macroscopic pieces are black, brittle, and have a characteristic sheen as seen in modern charcoal. Fig. 8 shows a scanning electron micrograph of a charcoal specimen, probably the remains of an axis such as a stalk of a Poa foliosa inflorescence. The specimen received no treatment other than the cutting of a flat face on the specimen with a razor blade and coating for scanning electron microscopy.

DISCUSSION

The profile analysed is likely to record vegetation change of a quite local nature. The site is on the western edge of Wireless Hill where, as is true for the whole island, winds are overwhelmingly north-westerly to south-westerly (Mawson, 1943: 30), blowing across thousands of kilometres of open ocean. Winds from other directions are uncommon, but when they do occur are usually gale force. There is no reason to assume major change in this wind pattern over the past 5000 years, so one could reasonably infer that pollen in peats on Wireless Hill would be derived mainly from vegetation close to the site or blown up to the site from the slopes and strand below. This inference appears to be justified since the pollen diagram shows an almost complete absence of a wide regional component. Barrow (1978) found that pollen in surface litter samples on South Georgia is principally derived from plants growing in communities very near sample sites. In the profile studied here Azorella pollen, for example, occurs only sporadically and in very low frequency, although Azorella selago is dominant in the feldmark community which covers about half the main part of Macquarie Island to the south, at altitudes above 250 m. Azorella pollen is common in surface samples in herbfield and feldmark situations on the main island (M. Salas, pers. comm.).

That the vegetation on or close to the site has been grass dominated for the past 5000 years or so is clear. Grass pollen is always present in huge quantities when compared with dicotyledon pollen, intact grass anthers have been encountered in all pollen preparations, and the relative abundance of immature grass pollen grains suggests a local source for the pollen. Grass phytoliths make up a significant proportion of the siliceous fraction of all samples. Phytoliths almost certainly represent grass growing on or close to the site, since they have little chance of becoming airborne once they rot out of the decaying foliage which has become incorporated in the surface litter layer. In dry, continental areas phytoliths may become airborne in dust, possibly being carried some distance (Baker, 1959a, b), but would be likely to remain in situ on Macquarie Island in the moist environments suitable for peat formation.

Vegetational changes recorded in the profile are not readily interpretable in terms of climatic variation. There are no major variations in ‘upland’ or ‘lowland’ components such as have allowed identification of climatic change on other subantarctic islands (Bellair and Delibrias, 1967; Bellair-Roche, 1972; Schalke and van Zinderen Bakker, 1971; Young and Schofield, 1973; Roche-Bellair, 1973, 1967a, b). Barrow (1978) could detect no evidence of major climatic variation over the past 10000 years on South Georgia by means of pollen analysis even though there was probably a readvance of valley glaciers about 5500 years BP (Stone, 1976).

Proc. LINN. Soc. N.S.W. 107 (1), (1982) 1983

D. R. SELKIRK, P.M.SELKIRK AND K. GRIFFIN 11

The sequence of events recorded in the samples can most readily be interpreted in terms of localized vegetational changes resulting from uplift of the site from a position close to sea level to its present altitude. That the cobbles underlying the deposit are those of an ocean beach rather than a lake-shore beach is clear. Only a substantial lake at 100 m would allow sufficient wave action to form a well-developed beach, and such a beach would be best developed at the lake’s eastern end, due to prevailing winds. Interpretation of the cobbles as those of a lakeside beach would imply loss of an extensive area of land to the west of the present Wireless Hill. For this there is no evidence. The basal sequence of the profile gives a clear indication of animal-disturbed vegetation, and taken together, both pollen and diatoms present in the basal samples point to elephant seals as the most likely cause of this disturbance.

The peaks in Callitriche pollen between 120 and 352 cm almost certainly represent periods of modification of the vegetation by animals. On Macquarie Island at present, Callitriche appears only to be locally abundant where there is animal disturbance and manuring of the vegetation. It is most common around elephant seal wallow areas, growing both on the ground between wallows, and as an aquatic plant in the water of abandoned and infrequently used wallows (Figs 5 and 9). Taylor (1955) described Callitriche as growing on very wet soils and in pools at low elevations, commonly colonizing abandoned seal wallows. Gillham (1961) pointed out the close association between Callitriche and animals, recording it as most common on and near seal wallows, and common in wet gentoo penguin rookeries on the ‘featherbed’ at Handspike Point. J. Scott (pers. comm.) reports Callitriche and Poa annua as locally luxuriant near abandoned gentoo nesting sites close to the sea, and notes that such sites are also commonly disturbed by elephant seals. At higher altitudes, similar but less luxuriant growth of Callitriche and Poa annua occurs in association with giant petrel colonies, although both plants are rare in the surrounding undisturbed tussock grassland (J. Scott, pers. comm.). Callitriche can occur also in small quantities in rockhopper penguin rookeries which may be at considerable altitude. Whether Callitriche can be associated with albatross nests on Macquarie Island is still unclear. Although Callitriche acts as a colonizing species on peat surfaces bared by landslip, providing 15-20% cover eighteen months after slippage, it appears to be absent from old well-vegetated slip sites (J. Scott, pers. comm.).

On other subantarctic islands, Callitriche also seems closely linked with animal disturbance. On South Georgia, Callitriche is almost entirely confined to seal wallow areas in Poa tussock grassland, but also occurs in ‘meadow’ bogs enriched by bird excreta (Smith, 1981). On Marion and Prince Edward Islands, Callitriche is locally important in areas manured by seals, rockhopper penguins and albatrosses, forming part of acommunity called by Huntley (1971) a biotic complex. Croome (1971) studied effects of albatross manuring on Marion Island, and found Callitriche abundant near albatross nests. Smith (1978) found that Cadlitriche occurred only in manured sites on Marion Island. Schalke and van Zinderen Bakker (1971) interpreted Callitriche peaks in their pollen diagrams as due to albatross nesting.

The peaks in Callitriche pollen at 20, 30 and 80 cm (Fig. 6) may represent bird activity. Black browed albatrosses and giant petrels have nested on Wireless Hill quite recently (G. Johnstone, pers. comm.) and could cause local flushes of Callitriche. However the peaks in Callitriche at 30 and 80 cm are also associated fairly closely with charcoal layers in the peat, discussed below.

If Callitriche pollen is to be used as an indicator of environmental conditions at a very localized site, then it is necessary to establish that its pollen is not transported far from its origin. The possibility of large inputs of windborne pollen needs to be eliminated. Analysis of pollen in a surface litter sample, a moss mat and a modern seal

Proc. LINN. Soc. N.S.W. 107 (1), (1982) 1983

12 HOLOCENE ENVIRONMENTAL CHANGE AND UPLIFT

wallow (Fig. 10) indicates that Callitriche peaks in the pollen record almost certainly represent vegetation on or close to the site. The surface litter sample was collected from the top of the profile analysed. Callitriche contributes less than 1% of total pollen and only 10% of total dicotyledon pollen. On the coast below and to the west of the collection site 1s a seal wallow area (Fig. 1) which provides a source of Callitriche.pollen which has, however, not been blown the 100 m up to the site on prevailing winds. Similarly, analysis of a mat of Amblystegium at 80 m a.s.1. on the Doctors Track (Fig. 1), above extensive seal wallow areas on both sides of the isthmus (Fig. 4) yielded Callitriche at levels of less than 1% on both a total pollen and dicotyledon-only basis. The Amblystegium mat was collected when extensive swards of Callitriche in the wallow areas were in full flower, and when prevailing winds were favourable for pollen transport.

Both the litter and the moss mat samples, taken in conjunction with an analysis of pollen from a modern seal wallow (Fig. 10), indicate that most Callitriche pollen is deposited very locally, and that transport to other sites is very minor. This is perhaps not surprising for a plant which grows as a low mat on very wet soils, or as an aquatic (Fig. 9) in a hyperoceanic environment with almost daily precipitation.

We interpret the main Callitriche peak at 344-352 cm as representing seal wallow conditions on or very close to the site. In these samples Callitriche pollen is markedly more abundant than elsewhere in the profile, and accounts for 65-88% of total dicotyledon pollen (Fig. 10). In modern wallows (Fig. 10) Callitriche reaches 95% of total dicotyledon pollen with Cotula, Stilbocarpa and other dicotyledons present in small amounts. On a dicotyledon-only basis the 294 cm sample is much poorer in Callitriche (20% of total dicotyledons), while at 80 cm it reaches 45% of total dicotyledons. The occurrence in the 394 cm, 344 cm and 294 cm samples of diatom suites rich in Pinnularia atwoodi is consistent with the interpretation from the pollen evidence, that

Surtace Litter Sample, Amblystegium Moss Mat, Modern Seal Wallow Mud Samples Sample at 349cm Depth Wireless Hill Doctors Track (Average Two Samples) Total Pollen = P= 1898 Tal Total Pollen =P= 411 Total Pollen £P = 2211 Total Pollen =P = 1383 (ea alae eal Poaceae = ase —_————]) Callitriche — kb Stitbocarpa — |5) =< Pleurophyllum — F- i} Cotula — F- l- Acaena — _—iéke Cardamine — -k le Azorella — {> Stellaria/Cerastium —- > Epilobium —— |b Crassula — k + =<1% Total Pollen Colobanthus = | - Each Scale Division -10% Total Pollen p Callitriche Shown es Solid Bar Exotic — b le Surface Litter Sample. Amblystegium Moss Mat, Modern Seal Wallow Mud Samples Sample at 349cm Depth Wireless Hill, Doctors Track (Average Two Samples) Dicotyledon Pollen Only =P 127 Dicotyledon Pollen Only = a 1 Dicotyledon Pollen Only £P= 578 Dicotyledon Pollen Only £P= 134 Callitriche Stilbocarpa Pleurophylium

Cotula

Acaena

Cardamine

Azorella Stellaria/Cerastiom

Epilobium Cressale ++ <1% Dicotyledon Pollen Colebanthus - Each Scale Division * 10% Dicotyledon Pollon and Exotics Callitriche Shown as Solid Bar

PTT TESTE

Exotic

Fig. 10. Pollen diagram comparing analysis of a surface litter sample, Amblystegium moss mat, modern seal wallow mud and sample at 349 cm depth in profile. Upper diagrams show % total pollen. Lower diagrams show % based on total dicotyledon plus exotic pollen only.

PROC. LINN. Soc. N.S.W. 107 (1), (1982) 1983

D. R.SELKIRK, P.M. SELKIRK AND K. GRIFFIN 13

the basal sequence of the profile represents an animal-disturbed area, most probably a seal wallow.

Since the basal Callitriche peak appears to represent seal wallow conditions, developed only at low altitudes, the pronounced peak in Pleurophyllum at 374 cm could appear anomalous, since Pleurophyllum hookert is very common in subglacial herbfield (Taylor, 1955) at altitudes of about 200 m or more. Pleurophyllum, however, is also a major component of communities on the raised beach terrace at the northern end of the west coast of the island. Taylor (1955) mentions elephant seal destruction of Pleurophyllum patches at numerous places on this terrace. The pollen record could well represent elephant seal invasion of such an established community, close to the sea.

If the basal portion of the sequence represents the local presence of seal wallows, there are important implications in the record for the tectonic history of Wireless Hill.