Stable isotopes of C and N have been used to assess the effect of the duration of the sea ice season on the structure of benthic, Antarctic coastal food webs. Samples of suspended particulate organic matter, macroalgae and macroinvertebrates were collected at five subtidal rocky sites across a latitudinal gradient along the western Antarctic Peninsula and among the South Shetland Islands. We tested the hypotheses that trophic positions of omnivores decrease, and food web structure becomes more redundant at higher latitudes. A latitudinal shift in the isotope baseline was detected for both δ¹³C and δ¹⁵N, but the trophic positions of macroinvertebrates and their relative positions along the δ¹³C axis and were basically constant across sites, even after rescaling stable isotope ratios to account for shifts in the baseline. Although the northernmost and southernmost study sites differed significantly in most of the metrics of the food web structure, changes with latitude and the duration of the sea ice season were non-monotonic. Highly productive phytoplankton blooms during the ice-free season at Esperanza Bay and Rothera Point may explain the observed pattern, as they result in a massive supply of planktonic organic matter to the detritus bank in the seabed and, hence, shorten the C range and increase trophic redundancy. If this hypothesis is correct, the intensity of the summer phytoplankton bloom can be as relevant for the structure of the benthic marine food web as the duration of the sea ice season.

C和N的稳定同位素已用于评估海冰季节持续时间对底栖，南极沿海食物网结构的影响。沿着南极半岛西部和南设得兰群岛之间的一个纬度梯度，在五个潮间带岩石点采集了悬浮颗粒有机物，大型藻类和大型无脊椎动物的样品。我们检验了杂食动物的营养位置减少，食物网结构在高纬度地区变得多余的假设。两个中检测到的同位素基线纬度偏移δ ¹³ C和δ ¹⁵ N，但无脊椎动物的营养位置和它们的相对位置沿δ ¹³即使重新定标了稳定的同位素比以说明基线的变化，C轴在整个站点上也基本上是恒定的。尽管最北端和最南端的研究地点在大多数食物网结构指标上均存在显着差异，但纬度和海冰季节持续时间的变化并非单调。在埃斯佩兰萨湾和罗瑟拉角的无冰季节，浮游植物的高产可能解释了观测到的模式，因为它们导致海底碎屑岸大量浮游有机物的供应，因此缩短了C范围并增加了营养冗余。如果这个假设是正确的，夏季浮游植物开花的强度与底栖海洋食物网的结构可能与海冰季节的持续时间一样重要。