Besides the climate change impact on krill based ecosystem uncertainties the factors of the ozone distribution asymmetry influence over South Ocean is discussed. The existence of the considerable zonal asymmetry in total ozone distribution over Antarctica due to the planetary waves in a polar stratosphere is observed last decades. As was shown by authors earlier in the latitudinal interval of 55-75°S in Antarctic spring months (Sep-Nov) the minimum of quasi-stationary wave (QSW) in total ozone content distribution are continuously located over the Antarctic Peninsula and Weddell Sea area - most productive krill population region, and QSW maximum - in the Ross Sea area and Australian sector. We expect that zonal asymmetry in total ozone distribution and its long-term spatial changes should impact to South Ocean ecosystem food chain, especially in primary level. The quasi-stationary minimum in ozone distribution over north Weddell Sea area should cause the increased ultraviolet irradiation (UVR) on sea surface in comparison to opposite area, where the lack of UVR should exist in spring month. These factors add the uncertainties to the information gaps in the status of Antarctic krill resources existed due to the insufficient recent scientific data. To study the possible influence upon ecosystem the available data of phytoplankton distribution in South Ocean in 1997-2007 and the fine-scale catch and effort data (C1 data) from vessels fishing for krill in the CAMLR Convention Area in 1974-2007 is started to analyze.