Concordance of interannual fluctuations in acoustically estimated densities of Antarctic krill around South Georgia and Elephant Island: biological evidence of same-year teleconnections across the Scotia Sea

Acoustic estimates of the densities of Antarctic krill, Euphausia superba, in areas around South Georgia (SG) and Elephant Island (EI) were compared f or seven austral summers between 1981 and 1997. Estimated densities of kril l at SG were most often lower than at EI, although this may simply have bee n a function of differences in the survey and data-analysis techniques used at each site. More interestingly, the magnitudes of density and between-ye ar gradients of density at each site were mirrored by those at the other lo cation; for example 1991 and 1994 were years of very low krill density at b oth SG and EI. There was no apparent lag in changes in density between site s, and ranked between-year gradients in density at both locations were clos ely correlated. These pronounced similarities suggest that densities of kri ll at both locations are linked directly, and may be impacted by the same g ross physical and biological factors (e.g. recruitment, dispersal and envir onmental variability) acting over the same temporal and spatial scales. The observed concordance also implies that the pelagic ecosystems at these wid ely separated sites (similar or equal to 1500 km distant at opposite sides of the Scotia Sea) are not operating in isolation. Fluctuations in krill de nsity were investigated with reference to cyclical variations in sea ice ex tent, and in air and sea-surface temperature. The resulting model suggests that the 1999/2000 austral summer will be one of low krill density.