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SCAR Bulletin 150, July 2003

Management Plan for
Antarctic Specially Protected Area No. 126
Byers Peninsula, Livingston Island, South Shetland Islands

ASPA 107 ASPA 108 ASPA 117 ASPA 121 ASPA 123 ASPA 124 ASPA 126

ASPA 126 Annex 1

CLIMATE GEOLOGY GEOMORPHOLOGY AND SOILS STREAMS AND LAKES VEGETATION
INVERTEBRATES, FUNGI AND BACTERIA BREEDING BIRDS BREEDING MAMMALS HISTORICAL FEATURES HUMAN ACTIVITIES / IMPACTS

6(i) Geographical coordinates, boundary markers and natural features
CLIMATE
No extended meteorological records are available for Byers Peninsula, but the climate is expected to be similar to that at Base Juan Carlos I, Hurd Peninsula. Conditions there indicate a mean annual temperature of below 0º C, with temperatures >0º C for at least several months each summer, and a relatively high precipitation rate estimated at about 800 mm/yr, much of which falls as rain in summer (Ellis-Evans 1996). The peninsula is snow-covered for much of the year, but is usually completely snow-free by the end of the summer. The peninsula is exposed to weather from the Drake Passage in the north and northwest, the directions from which winds prevail, and Bransfield Strait to the south.

GEOLOGY
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The bedrock of Byers Peninsula is composed of Upper Jurassic to Lower Cretaceous marine sedimentary, volcanic and volcaniclastic rocks, intruded by igneous bodies (see Smellie et al 1980; Crame et al 1993, Hathway and Lomas 1998) (Map 3 – IN PREP). The rocks represent part of a Mesozoic-Cenozoic magmatic arc complex, which is exposed throughout the whole of the Antarctic Peninsula region, although most extensively on the Byers Peninsula (Hathway and Lomas 1998). The interior, elevated, region of the eastern half of the peninsula – surrounded to the north and south by Holocene beach deposits – is dominated by Lower Cretaceous non-marine tuffs, volcanic breccias, conglomerates, sandstones and minor mudstones, with intrusions in several places by volcanic plugs and sills. The western half of the peninsula, and extending NW half-way along Ray Promontory, is predominantly Upper Jurassic-Lower Cretaceous marine mudstones, with sandstones and conglomerates, with frequent intrusions of volcanic sills, plugs and other igneous bodies. The NW half of Ray Promontory comprises mainly volcanic breccias of the same age. Mudstones, sandstones, conglomerates and pyroclastic rocks are the most common lithologies found on the peninsula. Expanses of Holocene beach gravels and alluvium are found in coastal areas, particularly on South Beaches and the eastern half of Robbery Beaches, with less-extensive deposits on President Beaches.
The Area is of high geological value because “the sedimentary and igneous rocks exposed at Byers Peninsula constitute the most complete record of the Jurassic-Early Cretaceous period in the northern part of the Pacific flank of the magmatic arc complex, and they have proved a key succession for the study of marine molluscan faunas (e.g. Crame 1984, 1995, Crame and Kelly 1995) and non-marine floras (e.g. Hernandez and Azcárte 1971, Philippe et al 1995).” (Hathway and Lomas 1998).

GEOMORPHOLOGY AND SOILS
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Much of the terrain consists of lithosols, essentially a layer of shattered rock, with permafrost widespread below an active layer of 30-70 cm depth (Thom 1978, Ellis-Evans 1996, Serrano et al 1996). Stone fields (consisting of silty fines with dispersed boulders and surficial clasts), gelifluction lobes, polygonal ground (both in flooded and dry areas), stone stripes and circles, and other periglacial landforms dominate the surface morphology of the upper platforms where bedrock outcrop is absent (Serrano et al 1996). Debris- and mud-flows are observed in several localities. Beneath some of the moss and grass communities there is a 10-20 cm deep layer of organic matter although, because vegetation is sparse over most of Byers Peninsula, there are no deep accumulations of peat (Bonner and Smith 1985). Ornithogenic soils are present especially in the Devils Point vicinity and on a number of knolls along President Beaches (Ellis-Evans 1996).
Parts of the interior of the peninsula have been shaped by coastal processes, with a series of raised beaches ranging from 3 to 54 m in altitude, some of which are over 1 km wide. A radiocarbon date for the highest beach deposits suggests that Byers Peninsula was largely free of permanent ice by 9700 yr B.P., while the lowest beach deposits are dated at 300 yr B.P (John and Sugden 1971, Sugden and John 1973). Lake sediment analyses, however, suggest a more recent general deglaciation of central Byers Peninsula of around 4000-5000 yr B.P., and radiocarbon dates in the locality need to be interpreted cautiously (Björck et al 1991a, b). In several places sub-fossil whalebones are embedded in the raised beaches, occasionally as almost entire skeletons. Radiocarbon dates of skeletal material from about 10 m a.s.l. on South Beaches suggest an age of between 2000 and 2400 yr B.P. (Hansom 1979). Pre-Holocene surfaces of Byers Peninsula exhibit clear evidence of a glacial landscape, despite the gentle landforms. Today only three small residual glaciers (comprising less then 0.5 km2) remain on Ray Promontory. The pre-existing, glacially modified, landforms have been subsequently overprinted by fluvial and periglacial processes, and moraines and other glacial deposits are scarce (Martínez de Pizón et al 1996).

STREAMS AND LAKES
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Byers Peninsula is perhaps the most significant limnological site in the South Shetland Islands / Antarctica Peninsula region, with over 60 lakes, numerous freshwater pools (differentiated from lakes in that they freeze to the bottom in winter), and a dense and varied stream network probably has the most stream types in the Maritime Antarctic. The gentle terrain favours water retention and waterlogged soils are common in the summer. However, the water capacity of the thin soils is limited, and many of the channels are frequently dry, with flow often intermittent except during periods of substantial snow melt or where they drain glaciers (López-Martínez et al 1996). Most of the streams drain seasonal snowfields and are often no more than 5-10 cm in depth (Ellis-Evans 1996). The larger streams are up to 4.5 km in length, up to 20 m in width, and 30-50 cm in depth in the lower reaches during periods of flow. Streams that drain to the west often have sizeable gorges (López-Martínez et al 1996), and gullies up to 30 m in depth have been cut into the uppermost, and largest, of the raised marine platforms (Ellis-Evans 1996). Above the Holocene raised beaches the valleys are gentle, with widths of up to several hundred metres.
Lakes are especially abundant on the higher platforms (i.e. at the heads of basins) and on the Holocene raised beaches near the coast. Midge Lake is the largest at 587x112 m, and deepest with a maximum depth of 9.0 m (Map 2). The inland lakes are all nutrient-poor and highly transparent, with extensive sediments in deeper water overlain by cyanobacterial mats. In some lakes, notably Chester Cone Lake about 500 m to the south of Midge Lake (Map 2), stands of aquatic moss Drepanocladus longifolius(= D. aduncus) are found growing at one to several metres in depth. Large masses of this moss are sometimes washed up along parts of the shoreline and may serve as an opportunistic habitat for Parochlus larvae (Bonner and Smith 1985).
The lakes are generally frozen to a depth of 1.0-1.5 m for 9-11 months of the year, overlain by snow, although surfaces of some of the higher lakes remain frozen year-round (Ellis-Evans 1996, López-Martínez et al 1996). On the upper levels of the central plateau, many small, shallow, slow-flowing streams flow between lakes and drain onto large flat areas of saturated lithosol covered with thick (3-10 cm) cyanobacterial mats of Phormidium sp.. These mats are more extensive than in any other Maritime Antarctic site thus far described, and reflect the unique geomorphology and relatively high annual precipitation of the Area. With spring melt there is considerable flush through most lakes, but outflow from many lakes may cease late in the season as seasonal snowmelt decreases. Some of the streams also contain substantial growths of cyanobacterial and green filamentous algae, along with diatoms and copepods. A number of relatively saline lakes of lagoonal origin occur close to the shore, particularly on President Beaches, and where these are used as southern elephant seal (Mirounga leonina) wallows these have been highly organically enriched. Those coastal shallow lakes and pools located behind the first raised beach often have abundant algal mats and crustaceans, including the copepods Boeckella poppei and Parabroteas sorsi, and occasionally the fairy shrimp Branchinecta gainii.

VEGETATION
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Although much of Byers Peninsula lacks abundant vegetation, especially inland (see Lindsay 1971), the sparse communities contain a diverse flora, with at least 56 lichen species, 29 mosses, 5 hepatics and 2 phanerogams having been identified as present within the Area. Numerous unidentified lichens and mosses have also been collected. This suggests the Area contains one of the most diverse representations of terrestrial flora known in the maritime Antarctic. A number of the species are rare in this part of the maritime Antarctic. For example, of the bryophytes, Anthelia juratzkana, Brachythecium austroglareosum, Chorisodontium aciphyllum, Ditrichum hyalinum, Herzogobryum teres, Hypnum revolutum, Notoligotrichum trichodon, Pachyglossa dissitifolia, Platydictya jungermannioides, Sanionia cf. plicata, Schistidium occultum, Syntrichia filaris and Syntrichia saxicola are considered rare. For A. juratzkana, D. hyalinum, N. trichodon and S. plicata, their furthest-south record is on Byers Peninsula. Of the lichen flora, Himantormia lugubris, Ochrolechia parella, Peltigera didactyla and Pleopsidium chlorophanum are considered rare.
Vegetation development is much greater on the south coast than on the north. Commonly found on the higher, drier raised beaches in the south is an open community dominated by abundant Polytrichastrum alpinum (=Polytrichum alpinum), Polytrichum piliferum (=Polytrichum antarcticum), P. juniperinum, Ceratodon purpureus, and the moss Pohlia nutans and several crustose lichens are frequent. Some large stands of mosses occur near President and South Beaches, where extensive snowdrifts often accumulate at the base of slopes rising behind the raised beaches, providing an ample source of meltwater in the summer. These moss stands are dominated mainly by Sanionia uncinata (=Drepanocladus uncinatus), which locally forms continuous carpets of several hectares. The vegetation composition is more diverse than on the higher, drier areas. Inland, wet valley floors have stands of Brachythecium austro-salebrosum, Campylium polygamum, Sanionia uncinata, Warnstorfia laculosa (=Calliergidium austro-stramineum), and W. sarmentosa (=Calliergon sarmentosum). In contrast, moss carpets are almost non-existent within 250 m of the northern coast, replaced by scant growth of Sanionia in hollows between raised beaches of up to 12 m in altitude, and of lichens principally of the genera Acarospora, Buellia, Caloplaca, Verrucaria and Xanthoria on the lower (2-5 m) raised beach crests, with Sphaerophorus, Stereocaulon and Usnea becoming the more dominant lichens with increasing altitude (Lindsay 1971).
On better drained ash slopes Bryum spp., Dicranoweisia spp., Ditrichum spp., Pohlia spp., Schistidium spp., and Tortula spp. are common as isolated cushions and turves with various liverworts, lichens (notably the pink Placopsis contortuplicata and black foliose Leptogium puberulum), and the cyanobacterium Nostoc commune. P. contortuplicata occurs in inland and upland habitats lacking in nitrogen, and is typical of substrata with some degree of disturbance such as solifluction; it is often the only plant to colonise the small rock fragments of stone stripes and frost-heave polygons (Lindsay 1971). It is usually found growing alone, though rarely with species of Andreaea and Usnea. N. commune covers extensive saturated areas on level or gently sloping, gravelly boulder clay from altitudes of between 60-150 m, forming discrete rosettes of about 5 cm in diameter 10-20 cm apart (Lindsay 1971). Scattered, almost spherical, cushions of Andreaea, Dicranoweisia, and Ditrichum are found on the driest soils. In wet, bird- and seal-influenced areas the green foliose alga Prasiola crispa is sometimes abundant.
Rock surfaces on Byers Peninsula are mostly friable, but locally colonised by lichens, especially near the coast. Volcanic plugs are composed of harder, more stable rock and are densely covered by lichens and occasional mosses. Usnea Plug is remarkable for its luxuriant growth of Himantormia lugubris and Usnea aurantiaco-atra (=U. fasciata). More generally, H. lugubris and U. aurantiaco-atra are the dominant lichen species on inland exposed montane surfaces, growing with the moss Andreaea gainii over much of the exposed rock with up to 80% cover of the substratum (Lindsay 1971). In sheltered pockets harbouring small accumulations of mineral soil, the liverworts Barbilophozia hatcheri and Cephaloziella varians (=exiliflora) are often found, but more frequently inter-mixed with cushions of Bryum, Ceratodon, Dicranoweisia, Pohlia, Sanionia, Schistidium, and Tortula. Sanionia and Warnstorfia form small stands, possibly correlated with the absence of large snow patches and associated melt streams. Polytrichastrum alpinum forms small inconspicuous cushions in hollows, but it may merge with Andreaea gainii cushions in favourable situations (Lindsay 1971).
Crustose lichens are mainly species of Buellia, Lecanora, Lecedella, Lecidea, Placopsis and Rhizocarpon growing on rock, with species of Cladonia and Stereocaulon growing on mosses, particularly Andreaea (Lindsay 1971). On the south coast moss carpets are commonly colonised by epiphytic lichens, such as Leptogium puberulum, Peltigera rufescens, Psoroma spp., together with Coclocaulon aculeata and C. epiphorella. On sea cliffs Caloplaca and Verrucaria spp. dominate on lower surfaces exposed to salt spray up to about 5 m, with nitrophilous species, such as Caloplaca regalis, Haematomma erythromma,and Xanthoria elegans often dominant at higher altitudes where seabirds are frequently nesting. Elsewhere on dry cliff surfaces a Ramalina terebrata - crustose lichen community is common. A variety of ornithocoprophilous lichens, such as Catillaria corymbosa, Lecania brialmontii, and species of Buellia, Haematomma, Lecanora, and Physcia occur on rocks near concentrations of breeding birds, along with the foliose lichens Mastodia tessellata, Xanthoria elegans and X. candelaria which are usually dominant on dry boulders.
Antarctic hairgrass (Deschampsia antarctica) is common in several localities, mainly on the south coast, and occasionally forms closed swards (e.g. at Sealer Hill); Antarctic pearlwort (Colobanthus quitensis) is sometimes associated. Both plants are quite abundant in southern gullies with a steep north-facing slope, forming large, occasionally pure stands with thick carpets of Brachythecium and Sanionia, although they are rarely found above 50 m in altitude (Lindsay 1971). An open community of predominantly Deschampsia and Polytrichum piliferum extends for several kilometres on the sandy, dry, flat raised beaches on South Beaches. A unique growth-form of the grass, forming isolated mounds 25 cm high and up to 2 m across, occurs on the beach near Sealer Hill. Deschampsia has been reported at only one locality on the north coast (Lair Point), where it forms small stunted tufts (Lindsay 1971).

INVERTEBRATES, FUNGI AND BACTERIA
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The microinvertebrate fauna on Byers Peninsula thus far described comprises 23 taxa (Usher and Edwards 1986, Richard et al 1994, Block and Stary 1996, Convey et al 1996): six Collembola (Cryptopygus antarcticus, Cryptopygus badasa, Friesea grisea, Friesea woyciechowskii, Isotoma (Folsomotoma) octooculata (=Parisotoma octooculata) and Tullbergia mixta; one mesostigmatid mite (Gamasellus racovitzai), five cryptostigmatid mites (Alaskozetes antarcticus, Edwardzetes dentifer, Globoppia loxolineata (=Oppia loxolineata), Halozetes belgicae and Magellozetes antarcticus); nine prostigmatid mites (Bakerdania antarcticus, Ereynetes macquariensis, Eupodes minutus, Eupodes parvus grahamensis, Nanorchestes berryi, Nanorchestes nivalis, Pretriophtydeus tilbrooki, Rhagidia gerlachei, Rhagidia leechi, and Stereotydeus villosus); and two Dipterans (Belgica antarctica and Parochlus steinenii).
Larvae of the wingless midge Belgica antarctica occur in limited numbers in moist moss, especially carpets of Sanionia, although it is of very restricted distribution on Byers Peninsula (found especially near Cerro Negro) and may be near its northern geographical limit. The winged midge Parochlus steinenii and its larvae inhabit the margins of inland lakes and pools, notably Midge Lake and another near Usnea Plug, and are also found amongst the stones of many stream beds (Bonner and Smith 1985, Richard et al 1994, Ellis-Evans pers comm 1999). During warm calm weather, swarms of adults may be seen above lake margins.
The diversity of the arthropod community described at Byers Peninsula is greater than at any other documented Antarctic site (Convey et al 1996). Various studies (Usher and Edwards 1986, Richard et al 1994, Convey et al 1996) have demonstrated that the arthropod population composition on Byers Peninsula varies significantly with habitat over a small area. Tullbergia mixta has been observed in relatively large numbers; it appears to be limited in Antarctic distribution to the South Shetland Islands (Usher and Edwards 1986). Locally, the greatest diversity is likely to be observed in communities dominated by moss cushions such as Andreaea spp. (Usher and Edwards 1986). Further sampling is required to establish populations and diversities with greater reliability. While further sampling at other sites may yet reveal the communities described at Byers Peninsula to be typical of similar habitats in the region, available data on the microfauna confirm the biological importance of the Area.
An analysis of soil samples collected from Byers Peninsula yielded several nematophagous fungi: in Deschampsia soil Acrostalagmus goniodes, A. obovatus, Cephalosporium balanoides and Dactylaria gracilis; in Colobanthus soil, Cephalosporium balanoides and Dactylella gephyropaga were found (Gray and Smith 1984). The basidiomycete Omphalina antarctica is often abundant on moist stands of the moss Sanionia uncinata (Bonner and Smith 1985).

BREEDING BIRDS
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The avifauna of Byers Peninsula is diverse, although breeding colonies are generally not large. Two species of penguin, the chinstrap (Pygoscelis antarctica) and the gentoo (P. papua), breed in the Area; although widely distributed in the region, Adélie Penguins (P. adeliae) have not been observed to breed on Byers Peninsula or its offshore islets. The principal chinstrap penguin colony is at Devils Point in the SW, where a rough estimate of about 3000 pairs was made in 1987; a more accurate count made in 1965 indicated about 5300 pairs in four discrete colonies, of which almost 95% were nesting on an islet 100 m to the south of Devils Point (Croxall and Kirkwood 1979, Woehler 1993). Small chinstrap penguin colonies have been reported on the northern coast, but no breeding pairs were reported in a 1987 survey. Gentoo penguins breed at several colonies on Devils Point, with approximately 750 pairs recorded in 1965. Two smaller gentoo colonies totalling about 400 pairs were reported on the northern coast in 1965 (Croxall and Kirkwood 1979, Woehler 1993). More recent data are not available.
The most recent data available for other breeding species are from a detailed survey conducted in 1965 (White 1965, in Croxall – BAS internal bird data reports). The most populous breeding species recorded then, with approximately 1760 pairs, was the Antarctic tern (Sterna vittata), followed by 1315 pairs of Wilson’s storm petrels (Oceanites oceanicus), approximately 570 pairs of cape petrels (Daption capense), 449 pairs of kelp gulls (Larus dominicanus), 216 pairs of southern giant petrels (Macronectes giganteus), 95 pairs of black-bellied storm petrels (Fregetta tropica), 47 pairs of blue-eyed cormorants (Phalacrocorax atriceps) (including those on nearshore islets), 39 pairs of brown skuas (Catharacta loennbergi), and 3 pairs of sheathbills (Chionis alba). In addition, prions (Pachytilla sp.) and snow petrels (Pagodroma nivea) have been seen on the peninsula but their breeding presence has not been confirmed. The census of burrowing and scree-nesting birds is considered an underestimate (White pers. comm. 1999). The majority of the birds nest in close proximity to the coast, principally in the west and south.

BREEDING MAMMALS
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Large groups of southern elephant seals (Mirounga leonina) breed on the Byers Peninsula coast, with a total of over 2500 individuals reported on South Beaches (Torres et al. 1981) – which is one of the largest populations of this species recorded in the South Shetland Islands. Large numbers haul out in wallows and along beaches in summer. Weddell (Leptonychotes weddellii), crabeater (Lobodon carcinophagous) and leopard (Hydrurga leptonyx) seals may be seen around the shorelines. Antarctic fur seals (Arctocephalus gazella) were once very abundant on Byers Peninsula (see below), but have not substantially recolonised the Area in spite of the recent rapid population expansion in other parts of the maritime Antarctic.

HISTORICAL FEATURES
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Following discovery of the South Shetland Islands in 1819, intensive sealing at Byers Peninsula between 1820 and 1824 exterminated almost all local Antarctic fur seals and southern elephant seals (Smith and Simpson 1987). During this period there was a summer population of up to 200 American and British sealers living ashore in dry-stone refuges and caves around Byers Peninsula (Smith and Simpson 1987). Evidence of their occupation remains in their many refuges, many of which still contain artifacts (clothing, implements, structural materials, etc.). Several sealing vessels were wrecked near Byers Peninsula and timbers from these ships may be found along the shores. Byers Peninsula has the greatest concentration of early 19th Century sealers’ refuges and associated relics in the Antarctic, and these are vulnerable to disturbance and/or removal.
Elephant seal numbers, and to some extent fur seal numbers, recovered after 1860, but were again decimated by a second sealing cycle extending to the first decade of the twentieth century.

HUMAN ACTIVITIES / IMPACTS
The modern era of human activity at Byers Peninsula has been largely confined to science. The impacts of these activities have not been described, but are believed to be minor and limited to items such as campsites, footprints, markers of various kinds, sea-borne litter washed onto beaches (e.g. from fishing vessels), and from human wastes and scientific sampling. Several wooden stake markers and a plastic fishing float were observed in the SW of the Area in a brief visit made in February 2001 (Harris 2001).