Algal canopy as a proxy for the disturbance history of understorey communities in East Antarctica

• Published in: Polar Biology
• Main Authors: Clark, GF, Stark, JS, Perrett, LA, Hill, Nicole, Johnston, EL
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2011
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); East Antarctica; Antarc*; Antarctica; Polar Biology
• Online Access: https://doi.org/10.1007/s00300-010-0931-8; http://ecite.utas.edu.au/72129

Much of the macroalgal zonation on Antarcticcoasts is thought to be maintained by ice scour. The frequencyand severity of ice scour typically decrease withdepth, which is hypothesized to drive the zonation of twocanopy-forming macroalgae, Desmarestia menziesii andHimantothallus grandifolius. If true, understorey communitiesshould share the same history of ice scour as theirrespective canopies, and their composition should varyaccordingly. To evaluate this prediction we collectedboulders from under each canopy species at two depths, 6and 12 m, at two sites on the coast of East Antarctica. Weexamined the hard-substrate communities growing onboulders and tested for differences in community compositionwith respect to canopy species, surface orientation,and depth. Communities under the different canopiesshowed some variation consistent with the hypothesizeddifference in disturbance history. Those under H. grandifoliusaccommodated a greater abundance and diversityof sponges, which is usually characteristic of older, latersuccessional communities. Differences were subtle, however,suggesting that canopies might be maintained by icedisturbance over large temporal scale relative to those atwhich understorey communities develop, and/or that canopiesthemselves influence understorey composition. Thisstudy describes patterns associated with one of the mostprominent examples of bathymetric zonation in shallowAntarctic benthos, and experimental work is now needed topartition the processes at work.