Photographs were taken every 0.5 m along three transects of 5.5 m leng
th on shallow rock faces at Signy Island, Antarctica, during the austr
al summer of 1991/1992. The percentage cover of substratum ranged from
0 to 100% and the colonising communities included representatives of
ten phyla. The zone from mean low-water neap level to 1.5 m depth was
mostly devoid of organisms as a result of the seasonal formation of th
e encrusting ice foot. Coralline and macroalgae dominated from 2 to 3
m, and animal groups from 3.5 to 5.5 m. Bryozoans, and to a lesser ext
ent sponges, were the most abundant animal phyla. Within the bryozoans
a succession of colonisation of different species was observed, the m
ost abundant two of which occupied >80% of substratum in places. Subst
ratum type seemed to be the main factor influencing community developm
ent in the shallow sublittoral at Signy Island, although ice impact pr
events community development in the top 1.5 m and limits it over the r
est of the transect down to 5.5 m. Depth and profile of substratum als
o influenced communities within this depth range (particularly taxonom
ic composition).