Summary
Antarctic fast ice is of key climatic and ecological importance, yet its distribution and variability are poorly understood (compared to pack ice). In this joint Australian-French study, we present a multi-disciplinary analysis of annual fast ice extent and variability in the Adélie Land coastal region (~134 to 143ºE) using NOAA satellite data from 1992 to 1999. Fast ice distribution in this region is intimately linked to that of grounded icebergs in waters of <~350m depth. Considerable interannual variability occurs in areal extent and the timing of annual formation and breakup, related to persistence in wind direction (and strength). Ephemeral mid-season breakouts/reformations also occur in a deep-water trough to the N/NW of Dumont d’Urville. The results are compared with breeding success data for the Emperor penguin (Aptenodytes forsteri) colony at Pointe Géologie (~66.7ºS, 140.0ºE). The timing of fast ice annual formation and breakout, its overall extent, and the extent and timing of fast ice “trough clearouts” – all relative to key phases in the penguin breeding cycle – appear to be important factors affecting breeding success. Successful penguin breeding seasons (success >75%) coincided with lower-than-average fast-ice extents and persistently short distances to preferred foraging grounds. During heavy (extensive) fast ice years, these feeding zones may remain ice-covered for long periods. Disastrous breeding seasons (success <20%) coincided with an average extent but persistently large distances to nearest open water or a higher-than-average extent plus highly variable distances. Poor-to-moderate breeding years (of ~40-50%) occurred with above-average extents combined with fairly large distances later in the breeding season. The overall correlation between breeding success and “distance” is high (R2 = 0.89). This work will be spatio-temporally extended by a new PhD project (Alex Fraser), and by combining the satellite-based analysis with detailed in situ observations acquired within the Antarctic Fast Ice Network (led by Petra Heil).