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annex 1

SCAR Bulletin 150, July 2003

Management Plan for
Antarctic Specially Protected Area No. 107
Emperor Island, Dion Islands, Marguerite Bay, Antarctic Peninsula

ASPA 107 Annex 1.

CLIMATE AND SEA ICE GEOLOGY, GEOMORPHOLOGY AND SOILS VEGETATION HUMAN ACTIVITIES / IMPACTS
INVERTEBRATES, FUNGI AND BACTERIA BREEDING BIRDS BREEDING MAMMALS


6(i) Additional information on the natural features of the Area.
CLIMATE AND SEA ICE
Extended meteorological records are not available for Dion Islands, but records from 1962-74 for Adelaide Base (formerly UK; now Teniente Luis Carvajal, Chile), show a mean daily maximum temperature of 3ºC in February (extreme maximum 9ºC) and a mean daily minimum of -8ºC in August (extreme minimum -44ºC). This general pattern is consistent with observations at the Dion Islands recorded by Stonehouse (1953) during the winter of 1949, who also noted that the dominant winds occurred from a northerly direction. The islands are surrounded by fast ice up to 2 m thick for about seven months of the year, with a variable presence of open water and pack ice during the summer.
GEOLOGY, GEOMORPHOLOGY AND SOILS
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The geology of the Dion Islands consists of dark fine-grained lavas and tuffs of Jurassic to Early Tertiary age belonging to the Antarctic Peninsula Volcanic Group (Dewar 1970, Moyes et al 1994). Andesitic and basaltic lavas and pyroclastic rocks dominate toward the south, while in the north are found well-bedded sedimentary and volcaniclastic rocks. Shales, sandstones, grits and conglomerates are also present, usually as thin units of up to about 1 m thick (Skinner 1969). Poorly preserved plant fossils have been observed on Consort Islands and Noble Rocks, where indeterminate carbonaceous compressions, presumably representing tree trunks, of up to 1 m across occur (Thomson 1972). Flattened, carbonised and mineralised logs, up to 4 m long and 50 cm across, are common in siltstones on these islands (Thomson and Griffiths 1994). Small veins of copper are prominent as green streaks on the rocks.
There is virtually no soil development in the island group, except for small pockets of ornithogenic mud composed largely of guano, decayed moss and Prasiola crispa, notably on Emperor Island. Deposits of pure guano 10-30 cm thick have been observed on the edge of the Emperor Island cormorant colony. On the raised pebble beach on the largest of the Courtier Islands, periglacial circles of a yellowish-brown clay suggest an ornithogenic origin, although bird colonies do not presently occupy the site. In moist depressions this soil type is colonised by the moss Sanionia uncinata (=Drepanocladus uncinatus). The soils have exceptionally high concentrations of Ca, P and Mg, and also of Na in soils associated with the seabird colonies, as, for example, near the cormorant colony on Emperor Island (Smith 1996).
Several small low-lying areas on the Courtier and Emperor islands consist of large pebbles, suggesting raised beach deposits. The deposits occur on the south-eastern side of Emperor Island and on the largest of the Courtier Islands. Small sorted soil circles are evident in the deposits at about 6 m above mean sea level on this island. The geomorphology of the Dion Islands has otherwise not been described.
BREEDING BIRDS
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Six species of birds have been recorded as breeding on Dion Islands. Owing to the difficulties of access, however, data are few and dated. Descriptions below are thus often based on limited and/or old observations and it should be emphasised that these data are therefore not necessarily representative of present numbers or trends.
The outstanding feature of the avifauna is the presence of a small colony of emperor penguins which typically breeds on a low-lying shingle beach and rocky headland on the northern coast of south-eastern Emperor Island. The colony was discovered in October 1948 by Stonehouse (1953), who studied the breeding behaviour and performance, while Glenister (1954) investigated emperor penguin embryology from specimens taken by Stonehouse. It is the only emperor penguin colony in this region of Antarctica; it is also the most northerly colony and possibly the smallest, and one of only two in which breeding occurs on land (the other is at Taylor Rookery, SPA No. 1). It is also the most isolated, being about 2500 km (by sea) from the nearest known breeding colony. Stonehouse (1953) reported that the birds spent most of their time on the low-lying beach, occupying an area of about 650 m2.
Stonehouse (1953) reported numbers of adult birds varying between 100 and 183 during the 1949 winter (observations between 5 June – 15 August), and from egg counts it was estimated that about 150 breeding pairs were present. In the previous year 100 adults and 70 chicks were counted. Egg-laying occurred from around 1 June until 29 June, 1949, with most eggs laid in the first week. Birds laid one egg per pair, and replacement eggs were not laid if originals were lost. Initially, eggs were passed a number of times between pair partners, eventually being held by the male for incubation over several months while their partners were at sea, most of which returned around the end of July / early August when hatching occurred. The numbers of adult birds present increased after hatching, with frequent arrivals and departures. Observations made on chicks the previous year showed they had formed crêches by October, and some evidence in the 1949 season suggested crêches were formed around a month earlier. A chick mortality rate of less than 10% was estimated by Stonehouse for this season.
Fluctuations in numbers have been discussed by Conroy (1975), Croxall and Kirkwood (1979) and Woehler (1993). Approximately 150 breeding pairs were observed until about 1968, with some evidence (based on aerial photographs) of an increase (possibly to about 500 pairs) in 1977. However, it is probable this latter count included Adélie penguins which breed nearby, as only 70-80 adults and about 20 chicks were reported from a ground count in late July 1978 (Poncet 1982). The most recent count was made in July 1999, when only 14 males with eggs were counted in the same location on Emperor Island. It is not known whether this number is typical of recent seasons. If so, continued presence of the colony may be marginal.
A small colony of Adélie penguins (Pygoscelis adeliae) in several groups occupies the south-eastern part of Emperor Island. A rough count in 1948 indicated about 500 pairs, while a 1969 estimate indicated about 175 pairs. The most recent data available (a rough estimate made in 1986) indicated a population of 700 breeding pairs (Poncet and Poncet 1987, Woehler 1993).
A small colony of blue-eyed cormorants (Phalacrocorax atriceps) was present in the Dion Islands in October 1948, although numbers were not recorded (Stonehouse 1949). About 50 pairs were recorded on Emperor Island on 30 August 1968 (Willey 1969), while a more precise nest count at the same location in February 1969 recorded 107 pairs and 33 pairs in two adjacent groups. About 200 empty nests were counted on broad ledges on the steep north-western side of Emperor Island in July 1978, and there was evidence of the smaller breeding group closer to the location of the emperor penguin colony (BAS internal records, Bonner and Smith 1984). In February 1986, 388 pairs were recorded in two main colonies on Emperor Island, one in the north and one in the southeast. Eight pairs were recorded nesting within the Adélie penguin colony (Poncet pers comm., 1999).
Kelp gulls (Larus dominicanus) and brown skuas (Catharacta loennbergi) are numerous, with several pairs nesting on the larger islands (Bonner and Smith 1984). A breeding pair of kelp gulls with a chick was observed on Consort Islands on 24 February 1969 (BAS internal records). Southern giant petrels (Macronectes giganteus), cape petrels (Daption capensis) and snow petrels (Pagodroma nivea) are frequently seen around the islands, but breeding of these or other seabirds that have been observed in the area is unconfirmed, the nearest major breeding site being Avian Island, 12.75 km to the north-west. A few Wilson’s storm petrel (Oceanites oceanicus) nests were noted on Emperor Island in February 1969 (BAS internal records).
VEGETATION
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Vegetation on Dion Islands is generally sparse, and the flora has not been described in detail. Collections have been made principally on Emperor and Consort islands. Phanerogams are absent from the island and there is a limited range of cryptogams, although there is a rich lichen flora. The few taxa recorded on the islands are typical of maritime Antarctic sites exposed to strong winds, sea spray and nitrogenous enrichment from seabirds. The flora of the Area is not regarded as possessing properties that in itself merits special protection. To date, six mosses and at least 19 lichen species have been identified as present within the Area (BAS Plant Database 1999).
Bryophytes are restricted to small patches dominated by Sanionia uncinata (=Drepanocladus uncinatus) in moist hollows where there is some soil accumulation. The most substantial stands, covering several square metres, occur on the largest of the Courtier Islands. Bryum pseudotriquetrum (=Bryum algens), Ceratodon purpureus and Pohlia nutans are usually associated. The moss Syntrichia princeps (=Tortula princeps) has been recorded on Courtier Islands and Polytrichastrum alpinum (=Polytrichum alpinum) has been recorded on Emperor Island.
The epipetric communities are composed entirely of lichens. Macrolichens, such as Usnea and Umbilicaria, are rare although are common in the general region. The most prominent lichens include Acarospora macrocyclos, Amandinea petermannii, Buellia anisomera, B. cf. latemarginata, B. russa, Caloplaca cirrochrooides, C. spp., Lecania brialmontii, Lecanora spp., Lecidea atrobrunnea, L. spp., Mastodia tessellata, Physcia caesia, Usnea antarctica, Verrucaria elaeoplaca, V. psychrophilia, Xanthoria candelaria and X. elegans. Haematomma erythromma is frequent on the largest of the Courtier Islands. The only soil encrusting lichen noted is Candelariella vitellina. Moist rock depressions and faces associated with sea bird colonies support small patches of the alga Prasiola crispa and cyanobactarium Phormidium.

INVERTEBRATES, FUNGI, BACTERIA
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The microinvertebrate fauna, fungi and bacteria on Dion Islands have yet to be investigated in detail. Nine species of microinvertebrate fauna have been recorded from the island group (BAS Invertebrate Database 1999): two Collembola (Cryptopygus antarcticus, Friesea grisea); one mesostigmatid mite (Gamasellus racovitzai), four cryptostigmatid mites (Alaskozetes antarcticus, Halozetes belgicae, Magellozetes antarcticus and Globoppia loxolineata (=Oppia loxolineata)); and two prostigmatid mites (Eupodes minutus and Pretriophtydeus tilbrooki). The dominant species are Cryptopygus antarcticus and Alaskozetes antarcticus.
Nematodes have been recorded as abundant in Sanionia uncinata on the largest of the Courtier Islands, but were rare in Prasiola growing on Emperor Island (Bonner and Smith 1985). A sample of Sanionia uncinata intermixed with Bryum pseudotriquetrum from Emperor Island yielded several nematode taxa: mostly of the genus Mesodorylaimus, with Plectus and Eudorylaimus also present (Spaull 1973). Of the tardigrades in the sample, most were Macrobiotus furciger and Hypsibius dujardini, with a small proportion of H. alpinum and H. pinguis also present. Of nine specimens recovered from a soil sample from Consort Islands all were H. renaudi (Jennings 1976). Rotifers have been recorded on Emperor Island, although no protozoans. Three predacious fungi have been isolated from the Dion Islands: an unidentified endoparasite from Sanionia uncinata on Courtier Islands; and Arthrobotrys robusta and Cephalosporium balanoides from Prasiola on Emperor Island (Gray and Smith 1984).
BREEDING MAMMALS AND MARINE ENVIRONMENT
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Crabeater seals (Lobodon carcinophagus) are common on ice floes near the islands, with Weddell seals (Leptonychotes weddellii) and Leopard seals (Hydrurga leptonyx) being less frequent visitors (Bonner ad Smith 1985). A single immature bull Elephant seal (Mirounga leonina) was seen on the largest of the Courtier Islands on 14 March 1981. The marine environment within the Area has not been investigated.

HUMAN ACTIVITIES AND IMPACTS
There has been little human activity at the Dion Islands. Visits have comprised a mixture of science and topographical survey. The impacts of activities such as these have not been described and are not known, but are believed to have been minor and limited to items such as transient disturbance to breeding birds, campsites, footprints, occasional litter, human wastes, scientific sampling and markers. A fuel drum, a box (possibly a food cache, as mentioned in 1969 field reports), and several poles were apparent in aerial photographs of Emperor Island taken in December 1998, although their status has not been assessed in the field.