Production and fate of faecal pellets during summer in an East Antarctic fjord

The abundance of small faecal pellets is high in marine waters. Little is k nown, however, about the processes governing their production and fate in t he water column. We investigated faecal pellet production and flux in relat ion to the phytoplankton and copepod assemblages present in Ellis Fjord, An tarctica. Results show that the phytoplankton community shifted from a domi nance of diatoms to that of a cryptomonad species during late January. This coincided with an increase in abundance of the small copepods Paralabidoce ra antarctica and Oithona similis, although Oncaea curvata was still the do minant species. The mean faecal pellet flux was 9943 pellets m(-2) d(-1). O nly 37% of the faecal pellet flux at 5 m sedimented to 10 m depth, 15% to 2 0 m, and 12% to 40 m depth. Our results suggest that recycling of faecal pe llets by copepods contributes to this decreased flux with increasing depth, which concurs with results from large scale oceanic studies. Additionally, we propose that the summer ice melt changes the physical characteristics o f the water column and the phytoplankton species abundance and distribution ; both of which potentially impact on the distribution and abundance of cop epods, thereby regulating faecal pellet flux.