Timing and rates of release of particulate organic matter (POM) beneath the Antarctic sea ice during the melting season are relatively unknown. To shed light on this topic, we investigated: i) quantity and biochemical composition of POM released below annual sea ice in Terra Nova Bay (TNB, Ross Sea, Antarctica) through sediment traps deployed at 10- and 30-m depth; ii) the abundance and taxonomic composition of phytoplankton; iii) the abundance and biochemical composition of two zooplankton species, namely the pteropods Clione limacina antarctica and Limacina helicina antarctica. Overall, our results show that in late spring-early summer in TNB the melting of annual sea ice determines a rapid release of particles into the underlying water column, and that those particles are transported downward at the rate of hours to days. POM fluxes were dominated by lipids, which probably resulted from zooplankton grazing activity on sea-ice algae and faecal pellets that were released into the water column. This, after the initial injection of particles, which were likely associated with sinking sympagic microalgal biomass derived from the sea ice melting, enhanced the nutritional value of POM. POM released beneath the sea ice, in turn, had a possible effect on the biochemical composition of the two pteropod species. Our results confirm that melting of sea ice in spring-summer each year in Antarctic coastal waters represents a fundamental step in the transfer of energy towards the higher trophic levels. Evidence of a decline in Antarctic sea ice over the last five years, plausibly as a consequence of global warming, underlines a conspicuous decline in habitat availability for sea-ice algae and, as a consequence, a drop in the availability of food for pteropods and the higher trophic levels of the coastal Antarctic Ocean.

在融化季节，南极海冰下的颗粒状有机物（POM）的释放时间和释放速率尚不清楚。为了阐明这一主题，我们研究了：i）通过分布在10-m和30-m深度的沉积物捕集器，在Terra Nova湾（TNB，Ross海，南极洲）的年海冰以下释放的POM的数量和生化组成；ii）浮游植物的丰度和分类学组成；iii）两种浮游动物种类的丰富度和生化组成，即翼足类Clione limacina antarctica和Limacina helicina antarctica。总的来说，我们的结果表明，TNB的春末夏初，每年的海冰融化决定了颗粒快速释放到下面的水柱中，并且这些颗粒以小时到几天的速度向下运输。POM通量主要由脂质引起，这可能是由于浮游动物对放到水柱中的海冰藻类和粪便颗粒的放牧活动造成的。在最初注入可能与下沉的海冰融化产生的象征性微藻生物质有关的颗粒后，这增强了POM的营养价值。反过来，在海冰下释放的POM可能对这两种翼足类物种的生化成分产生影响。我们的结果证实，南极沿海水域每年春夏季的海冰融化代表着向更高营养级的能量转移的基本步骤。过去五年南极海冰减少的证据，可能是全球变暖的结果，突显了海冰藻类的栖息地可利用性显着下降，结果，翼足类和and足类食物的可利用性下降了。南极沿海地区较高的营养级别。