Environmental drivers of the physiological condition of mature female Antarctic krill during the spawning season: implications for krill recruitment

Abstract

Southern Ocean pelagic productivity relies on the abundance of Antarctic krill Euphausia superba, which fluctuates on a 5-7 yr cycle and is driven by interannual variability in recruitment. The western Antarctic Peninsula (wAP) is home to a significant proportion of the circum-Antarctic krill biomass and is the focus of the krill fishery. The wAP is warming at a rate quicker than most other places on Earth, with notable regional changes in the pelagic ecosystem. There is a major gap in our understanding of how environmental variability affects the reproductive success of krill. We used historical krill population data collected at the wAP (January 1993-2008, Palmer Antarctica Long Term Ecological Research) to assess the effects of environmental variability on the condition of mature female krill during the spawning season and its relationship with krill recruitment. Mature female krill condition during the spawning season was positively correlated with recruitment the subsequent year. Results of generalized additive models indicated that the predominant drivers of krill condition during the spawning season were climatological (Southern Annular Mode and Multivariate El Niño Southern Oscillation Index), though the timing of sea ice advance and retreat, and diatom concentrations were also important. Gaining a better understanding of the oceanographic and climatological factors that affect the physiological condition of mature female krill is critical for predicting future demographic patterns and responses to change. Results from our study emphasize the importance of including the effects of climate change in the management models for the Antarctic krill fishery.