Extremely large aggregations of collembolan eggs on Humble Island, Antarctica: a response to early seasonal warming?

In January 2007 we discovered numerous large aggregations of collembolan eggs on Humble Island near Palmer Station (64 degrees 46'S, 64 degrees 03'W). These aggregations were found in damp areas under rocks, moss, mats of the terrestrial alga Prasiola crispa, and at the interface between vegetation and the rocky substrate. Aggregations ranged in size from hundreds of eggs to the largest, whose estimated size exceeded 2 million eggs. Such aggregations were not observed in previous years. Associated with these aggregations were two collembolan species, Cryptopygus antarcticus (Willem) and Friesea grisea (Schaffer). Spring warming occurred approximately 7 weeks earlier in 2006 compared to the previous year. This early warming and consequent extended period of relatively high temperatures may have modified thermal and hydric conditions favoring collembolan growth and development and the formation of these large aggregations.