Shallow benthic Antarctic food webs recover complexity after disturbance

Natural disturbance events are expected to increase with climate change. This is particularly evident in polar regions where reduced winter sea-ice has increased movement of icebergs, and thus seafloor scouring. This predominantly affects shallow near-coast habitats, where iceberg scours can decimate local benthic ecosystems. Various metrics can be employed to measure recovery and resilience of ecosystems affected by disturbance. Here, we build a food web model for a near-shore benthic ecosystem along the West Antarctic Peninsula to evaluate the ecosystem’s response to iceberg scouring and predict its response to increasing future impacts. The overall food web structure was consistent with other Antarctic benthic food webs with a low mean trophic level and connectance, a high degree of omnivory and similar average path length compared to more temperate systems. We show that chronically disturbed shallow (5 m) habitats had lower food web complexity than deeper (10-25m) habitats where disturbance intensity and frequency was reduced. Recovery with time since last disturbance showed that recently disturbed food webs had similar levels of complexity to those that had been undisturbed for 8+ years but complexity fell to a minimum after 2 years of disturbance before recovering gradually. This might be due to the influx of mobile scavengers immediately post scour. We identified some highly connected species within the food web that are found across most of the Antarctic coastal shallows, such as the starfish Odontaster validus and conclude that these may be key to maintaining resilience in these ecosystems with increasing climate change.