Mäkelä Anni, Witte Ursula, Archambault Philippe
Oceanlab, School of Biological Sciences, University of Aberdeen, Newburgh, Aberdeenshire, United Kingdom.
Institut des Sciences de la mer de Rimouski, Université du Québec à Rimouski, Rimouski, Canada.
PLoS One. 2017 Aug 29;12(8):e0183034. doi: 10.1371/journal.pone.0183034. eCollection 2017.
Climate change driven alterations to patterns of Arctic marine primary production, with increasing phytoplankton- and decreasing ice algal production, have the potential to change the resource utilisation and trophic structure of the benthic communities relying on the algae for food. To predict the benthic responses to dietary changes, we studied the macroinfaunal community compositions, and used the faunal δ13C and δ15N signatures to investigate their main food sources and trophic positions in North Water (NOW) and Lancaster Sound (LS) polynyas in the Canadian Arctic Archipelago. Macroinfaunal density (10 952 ind. m-2) and biomass (3190 mg C m-2) recorded in NOW were higher than previously found in the Arctic at depths >500m, and significantly higher than in LS (8355 ind. m-2 and 2110 mg C m-2). This was attributed to higher particulate organic matter fluxes to seafloor in NOW. Polychaetes were significant taxa at both sites in terms of density and biomass, and in addition crustacean density in NOW and bivalve density in LS were high. Facultative filter and surface deposit feeders were highly prevalent at both sites, suggesting feeding plasticity is a successful strategy for accessing different food sources. The macrofaunal δ13C signatures reflected the signatures of pelagic particulate organic matter at the sites, and an isotope mixing model confirmed phytoplankton as the main food source for most taxa and feeding guilds. The food web length in LS was longer than in NOW (3.2 vs. 2.8 trophic levels). This was attributed to a larger reliance on reworked organic matter by the benthic community in LS, whereas the high export fluxes at the highly productive NOW resulted in higher rates of selective consumption of fresh algal matter. Despite studies suggesting that loss of ice algae from consumer diets in the Arctic might have a negative impact on the benthos, this study suggests that Arctic macrobenthic communities thrive using phytoplankton as their main food source and should thus be able to cope or even benefit from predicted changes to patterns of primary production.
气候变化导致北极海洋初级生产模式发生改变，浮游植物产量增加而冰藻产量减少，这有可能改变依赖藻类为食的底栖生物群落的资源利用和营养结构。为了预测底栖生物对饮食变化的反应，我们研究了大型底栖动物群落组成，并利用动物的δ13C和δ15N特征来研究它们在加拿大北极群岛的北水（NOW）和兰卡斯特海峡（LS）冰间湖中的主要食物来源和营养级。NOW记录的大型底栖动物密度（10952个个体/平方米）和生物量（3190毫克碳/平方米）高于此前在北极深度>500米处发现的水平，且显著高于LS（8355个个体/平方米和2110毫克碳/平方米）。这归因于NOW海底的颗粒有机物质通量更高。多毛类在两个地点的密度和生物量方面都是重要类群，此外NOW的甲壳类密度和LS的双壳类密度较高。兼性滤食者和表面沉积物摄食者在两个地点都非常普遍，这表明摄食可塑性是获取不同食物来源的成功策略。大型底栖动物的δ13C特征反映了各地点浮游颗粒有机物质的特征，同位素混合模型证实浮游植物是大多数类群和摄食类群的主要食物来源。LS的食物网长度比NOW长（3.2个营养级对2.8个营养级）。这归因于LS的底栖生物群落对再加工有机物质的依赖性更大，而高产的NOW的高输出通量导致对新鲜藻类物质的选择性消费率更高。尽管有研究表明北极消费者饮食中冰藻的减少可能对底栖生物有负面影响，但本研究表明北极大型底栖生物群落以浮游植物为主要食物来源而繁荣，因此应该能够应对甚至受益于预测的初级生产模式变化。
