Data: The roles of sea-ice, light and sedimentation in structuring shallow Antarctic benthic communities

Data repository for the paper: "The roles of sea-ice, light and sedimentation in structuring shallow Antarctic benthic communities" Graeme F. Clark, Jonathan S. Stark, Anne S. Palmer, Martin J. Riddle, Emma L. Johnston. PLoS ONE Data are boulder communities (epifauna), annual light budgets, and sediment traps. See the paper for more details. ABSTRACT On polar coasts, seasonal sea-ice duration strongly influences shallow marine environments by affecting environmental conditions, such as light, sedimentation, and physical disturbance. Sea-ice dynamics are changing in response to climate, but there is limited understanding of how this might affect shallow marine environments and benthos. Here we present a unique set of physical and biological data from a single region of Antarctic coast, and use it to gain insights into factors shaping polar benthic communities. At sites encompassing a gradient of sea-ice duration, we measured temporal and spatial variation in light and sedimentation and hard-substrate communities at different depths and substrate orientations. Biological trends were highly correlated with sea-ice duration, and appear to be driven by opposing gradients in light and sedimentation. As sea-ice duration decreased, there was increased light and reduced sedimentation, and concurrent shifts in community structure from invertebrate to algal dominance. Trends were strongest on shallower, horizontal surfaces, which are most exposed to light and sedimentation. Depth and substrate orientation appear to mediate exposure of benthos to these factors, thereby tempering effects of sea-ice and increasing biological heterogeneity. However, while light and sedimentation both varied spatially with sea-ice, their dynamics differed temporally. Light was sensitive to the site-specific date of sea-ice breakout, whereas sedimentation fluctuated at a regional scale coincident with the summer phytoplankton bloom. Sea-ice duration is clearly the overarching force structuring these shallow Antarctic benthic communities, but direct effects are imposed via light and sedimentation, and mediated by habitat characteristics. Data files: Boulder_community_data.csv - Percentage cover data for sessile organisms (invertebrates and algae) growing on boulder surfaces. - Columns 1 to 5 are sample attributes, columns 6 to 57 are measured variables (species or bare space). Light_budget_data.csv - Annual light budgets at each site, recorded by light metres. - Columns are site name and annual light budget (mol photons m-2 year-1) Sediment_trap_data.csv - Total sediment collected in sediment traps - Columns are site label, position in bay, replicate, dates deployed and retrieved, and the calculated sediment flux (g m-2 d-1)