Dka. Barnes et al., COLONIZATION AND DEVELOPMENT IN ENCRUSTING COMMUNITIES FROM THE ANTARCTIC INTERTIDAL AND SUBLITTORAL, Journal of experimental marine biology and ecology, 196(1-2), 1996, pp. 251-265
A total of 985 rocks with a wide range of surface areas were examined
from six locations at Signy Island in the maritime Antarctic. The shal
lowest site was intertidal and the deepest at 42 m. The probability of
coralline algae occurring was found to increase with surface area and
depth of rocks, implying decreased levels of turnover or physical dis
turbance with increasing rock size and depth. Percent area colonised,
number of animal phyla, bryozoan species and bryozoan colonies all inc
reased both with rock surface area and depth. The largest rocks in the
intertidal had broadly similar levels of colonisation and community d
evelopment as did the smallest at 42 m. Thus, because of depth-depende
nt ice-scour, community development in the Antarctic sublittoral may b
e followed along a pseudo-time sequence by using two axes (substratum
size and depth) of environmental stability. Frequent disturbance appea
rs to be responsible for maintaining the level of diversity and preven
ting monopolisation. Bryozoans and polychaetes were the most abundant
encrusting animal groups, although tunicates and sponges were the domi
nant overgrowth competitors. The faunal elements of the colonising bio
ta were almost entirely confined to the undersurfaces of rocks whereas
algae dominated upper surfaces. In most bryozoan species the proporti
on of colonies occurring on the upper surfaces of rocks increased with
depth to 34 m and then decreased at 42 m where silt deposition appare
ntly became a major influence. Such a shift in distribution may reflec
t decreasing current velocities, and therefore reduced disturbance to
animal feeding, and/or decreasing growth of coralline algae due to red
uced light availability.