Fast ice distribution in Adelie Land, East Antarctica: interannual variability and implications for emperor penguins Aptenodytes forsteri

• Published in: Marine Ecology Progress Series
• Main Authors: Massom, RA, Hill, K, Barbraud, C, Adams, ND, Ancel, A, Emmerson, L, Pook, MJ
• Format: Article in Journal/Newspaper
• Language: English
• Published: Inter-Research 2009
• Subjects: Environmental Sciences; Ecological Applications; Ecosystem Function; Antarctic; East Antarctica; Adelie Land; Antarc*; Antarctica; Aptenodytes forsteri; Emperor penguins; Iceberg*
• Online Access: http://www.int-res.com/abstracts/meps/v374/p243-257/; https://doi.org/10.3354/meps07734; http://ecite.utas.edu.au/62215

Antarctic fast ice is of key climatic and ecological importance, yet its distribution andvariability are poorly understood. We present a detailed analysis of fast ice along the Adlie Land coast(East Antarctica) using satellite data from 1992 to 1999. Fast ice formation along this coastline is intimatelylinked to grounded iceberg distribution in waters of <350 m depth. Considerable interannualvariability occurs in areal extent and formation/break-up; the variability is related to wind direction.Distance to the fast ice edge and its extent are major determinants of emperor penguin Aptenodytesforsteri breeding success at Pointe Gologie. Of crucial importance are the frequency and duration offast ice break-out events in the deep-water trough north-northwest of the colony. Successful penguinbreeding seasons in 1993, 1998 and 1999 ([number of fledged chicks in late November / number ofbreeding pairs] >75% success) coincided with lower-than-average fast ice extents and persistentlyshort distances to nearest open water (foraging grounds), and corresponded to a strong positive phaseof the Southern Annular Mode. Poor breeding seasons in 1992, 1994 and 1995 (success <15%) coincidedwith average to slightly higher-than-average ice extents and persistently long distances to foraginggrounds. Poor-to-moderate breeding years (success ~40 to 50%), e.g. 1996 and 1997, occurred withabove-average ice extents combined with fairly long distances from breeding to foraging grounds duringthe chick nurturing season. The overall correlation between breeding success and distance washigh (r2 = 0.89), albeit based on a limited number of years (n = 8). Substantially less fast ice was presentin two Argon satellite photographs taken in August and October 1963. This coincided with a highlysuccessful breeding season and appears to have been related to stronger and more southerly winds.