Distribution of Calanus species in Kongsfjorden, a glacial fjord in Svalbard

Abstract

The distribution of Calanus species was investigated in Kongsfjorden in summer of 1996 and 1997. In both years Calanus finmarchicus and Calanus glacialis dominated, although the boreal C. finmarchicus was more abundant than the Arctic C. glacialis in 1997. This coincided with a 2°C higher water temperature at 50 m in 1997, indicating stronger influence of Atlantic origin water that year. Adverted Calanus finmarchicus occurred in deep and subsurface layers of the outer fjord in 1996 (200 ind. m 3 , mainly CIII). A less abundant local population aggregated in surface layers of the inner fjord (100 ind. m -3 ). Similarly, advected C. finmarchicus occurred in subsurface layers in 1997 (446 ind. m -3 , mainly CIII and CIV) and a local population in surface layers (183 ind. m -3 , mainly CI). Calanus glacialis in 1996 aggregated as CII and CIII in the deep layers of the outer ford (272 ind. m 3 ), whereas CIII-CV were abundant (216 ind. m -3 ) in cold surface waters of the inner fjord. In 1997 C. glacialis (mostly CIIII-CV) was more abundant in the outer than in the inner part of the fjord (40 and 192 ind. m -3 , respectively). Within Kongsfjorden, Calanus finmarchicus needs one year to complete its life cycle, whereas Calanus glacialis needs two. Calanus hyper-boreus seems to be an expatriate in the fjord system.