Effect of light regime on the seasonal cycle of Antarctic krill

Flavia Höring presented results on the effect of light regime on the seasonal cycle of Antarctic krill at the 3rd International Symposium on Krill in June 2017 in St. Andrews, Scotland. Find the talk here.

Abstract: The success of Antarctic krill in the Southern Ocean is mostly determined by its ability to synchronise its life cycle to extreme latitudinal and seasonal changes of photoperiod and food supply. Previous lab experiments suggest that photoperiod is an essential environmental Zeitgeber, which controls the seasonal physiology of Antarctic krill. This study aims to investigate the role of photoperiod in controlling seasonal rhythms of physiology, growth and maturation of Euphausia superba under different latitudinal light regimes. Long-term lab experiments were conducted over a two-year period and under constant food supply simulating the natural annual cycle of light at 52°S, 62°S and 66°S and constant darkness. Seasonal cycles of growth and maturity were found under the latitudinal light treatments indicating that light regime acts as Zeitgeber. The patterns observed under constant darkness suggest an endogenous timing system controlling the growth and maturity cycle of Antarctic krill. The observation of a longer critical photoperiod under the high-latitude light regime indicates an adaptation to more extreme light conditions.