Analysing benthic communities in the Weddell Sea (Antarctica): a landscape approach

Abstract

In this study, I introduce the use of methods borrowed from landscape ecology to analyse quantitatively spatial patterns in Antarctic mega-epibenthic communities. This discipline focuses on the notion that communities can be observed as a patch mosaic at any scale. From this perspective I investigated spatial patterns based on landscape indices in an undisturbed benthic assemblage across different stations; and through successional stages after iceberg disturbance. The present study i) characterizes coverage and abundance of sessile benthic fauna, ii) describes faunal heterogeneity using ordination techniques and identifies "structural species" from each successional stage, iii) analyses changes of growth-form patterns through succession, and iv) relates the life-history traits of "structural species" to differences in distribution during the course of Antarctic succession. For this purpose, underwater photographs (1m2 each) corresponding to 6 stations from the southeastern Weddell Sea shelf were investigated. Overall, the different stations within the undisturbed assemblage showed large differences in patch characteristics, diversity, and interspersion. Canonical Correspondence Analysis (CCA) revealed a gradual separation from early to older stages of succession after iceberg disturbance. Conceptually, the results describe a gradient from samples belonging to early stages of recovery with low cover area, low complexity of patch shape, small patch size, low diversity, and patches poorly interspersed to samples from later stages with higher values of these indices. Several "structural species" were identified among the stages, and information on their coverage, abundance, and size is provided. I conclude by comparing the selected "structural species" and relating their life history traits to differences in distribution during the course of Antarctic succession.