Body size and growth of benthic invertebrates along an Antarctic latitudinal gradient
Much has been made of body-size variability with latitude, and extreme body sizes in polar waters, but body size has
never been investigated along a latitudinal gradient within polar waters. The Scotia arc and Antarctic Peninsula are ideal
for latitudinal studies, and a number of species extend along the length of this region. We studied body size in two
gastropod molluscs, Margarella antarctica and Nacella concinna, an echinoid, Sterechinus neumayeri, and two bryozoans,
Celleporella bougainvillea and Inversiula nutrix, at six sites from South Georgia to Adelaide Island (54–681S). We
hypothesised that size, age, and growth would not correlate with latitude, given the uniformity of conditions (i.e.
temperature, dissolved oxygen, etc.) within the Polar Frontal Zone. We found significant differences in size of all five
species among our study sites, but not a linear trend, nor one that correlated with latitude. In bryozoans, this result was
because growth was positively and age negatively correlated with latitude—resulting in little difference in overall size. In
the grazer organisms (the two gastropods and the echinoid) a correlation with local food availability (chlorophyll a
concentration) did not correlate with latitude. Fecundity in the gastropod M. antarctica was positively correlated with
body size, and body size also was influenced by food availability. We conclude that variation in body size in all five study
taxa was governed by local factors such as food availability and competition and not by latitude.
Authors: Linse, Katrin, Barnes, David K.A., Enderlein, Peter