Fjord and shelf food webs are frequently supplemented by the advection of external biomass, which in high-latitude seas often comes in the form of lipid-rich copepods that can support a wide range of fish species, including Northeast Arctic cod (). A seasonal match or mismatch at the lower trophic levels (phytoplankton and zooplankton) is central in determining how much energy and biomass is available for higher trophic levels (fish). Here, we quantify the inflow of the copepod into the Vestfjorden fjord system using high-resolution measurements of ocean currents and zooplankton (laser optical plankton counter). We evaluate a spatio-temporal match/mismatch between the phytoplankton bloom and and assess the input of advected copeods at the lower trophic level fjord and shelf food web based on an integrative approach employing stable isotope analyses (C, N), fatty acid trophic marker analyses, and biovolume spectrum analyses. Our results suggest two different sources of the population in the fjord/shelf system: one fraction overwintered locally and started ascending early to feed on the phytoplankton bloom that peaked around April 11. The other fraction had only recently (end of April) been and still was being advected from the oceanic overwintering habitats. Ca. 119 g C/s of were advected into the fjord, comparable to the biomass of advected into an Arctic fjord, and the mesozooplankton community was dominated by the copepod. The fjord food web was tightly coupled between the phytoplankton spring bloom, the local part of the population (trophic level 1.8–2.4) and cod larvae (high levels of wax esters). On the shelf, our results suggest that the impact of advected in the food web is at its starting point (low trophic level, large difference of δC of POM and ). We highlight important factors that can contribute to the successful spawning of Northeast Arctic cod: an extended phytoplankton bloom that can support both locally and advected , which in turn can supply the essential nauplii prey for first-feeding cod larvae.

中文翻译：

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平流对以桡足类 Calanus finmarchicus 为主的亚北极峡湾食物网的影响


峡湾和陆架食物网经常得到外部生物量平流的补充，这些生物量在高纬度海洋中通常以富含脂质的桡足类形式出现，可以支持多种鱼类，包括东北北极鳕鱼。较低营养级（浮游植物和浮游动物）的季节性匹配或不匹配对于确定较高营养级（鱼类）可用的能量和生物量至关重要。在这里，我们使用洋流和浮游动物的高分辨率测量（激光光学浮游生物计数器）来量化桡足类流入 Vestfjorden 峡湾系统的流量。我们基于采用稳定同位素分析（C，N）、脂肪酸营养标记的综合方法，评估浮游植物水华之间的时空匹配/不匹配，并评估低营养级峡湾和陆架食物网中平流桡足类的输入分析和生物体积谱分析。我们的研究结果表明，峡湾/陆架系统中有两种不同的种群来源：一部分在当地越冬，并提前开始上升，以 4 月 11 日左右达到高峰的浮游植物繁殖为食。另一部分直到最近（4 月底）才开始并仍然存在。是从海洋越冬栖息地平流而来的。约。 119 g C/s 被平流输送到峡湾，与平流输送到北极峡湾的生物量相当，并且中型浮游动物群落以桡足类动物为主。峡湾食物网与春季浮游植物、当地种群（营养级 1.8-2.4）和鳕鱼幼虫（蜡酯含量高）紧密相连。在架子上，我们的结果表明，食物网中平流的影响才刚刚开始（营养级低，POM 和 的 δ13C 差异较大）。 我们强调了有助于东北北极鳕鱼成功产卵的重要因素：浮游植物大量繁殖，可以支持本地和平流，进而可以为首次进食的鳕鱼幼虫提供必要的无节幼体猎物。