Abundance, biomass and secondary production of benthic megafauna on the Barents Sea shelf in 2008 and 2009

Megabenthos plays a major role in the overall energy flow on Arctic shelves, but information on megabenthic secondary production on large spatial scales is scarce. Here, we estimated for the first time megabenthic secondary production for the entire Barents Sea shelf by applying a species-based empirical model to an extensive dataset from the joint Norwegian- Russian ecosystem survey. Spatial patterns and relationships were analyzed within a GIS. The environmental drivers behind the observed production pattern were identified by applying an ordinary least squares regression model. Geographically weighted regression (GWR) was used to examine the varying relationship of secondary production and the environment on a shelfwide scale. Significantly higher megabenthic secondary production was found in the northeastern, seasonally ice-covered regions of the Barents Sea than in the permanently ice-free southwest. The environmental parameters that significantly relate to the observed pattern are bottom temperature and salinity, sea ice cover, new primary production, trawling pressure, and bottom current speed. The GWR proved to be a versatile tool for analyzing the regionally varying relationships of benthic secondary production and its environmental drivers (R² = 0.73). The observed pattern indicates tight pelagic- benthic coupling in the realm of the productive marginal ice zone. Ongoing decrease of winter sea ice extent and the associated poleward movement of the seasonal ice edge point towards a distinct decline of benthic secondary production in the northeastern Barents Sea in the future.

大型底栖生物（megabenthos）在北极陆架的整体能量流动中发挥着关键作用，但目前关于大空间尺度下大型底栖次级生产力（megabenthic secondary production）的研究资料仍较为稀缺。本研究首次借助挪-俄联合生态系统调查的海量数据集，采用基于物种的经验模型，估算了整个巴伦支海陆架的大型底栖次级生产力。研究通过地理信息系统（GIS）分析了其空间分布格局与相关关联，并运用普通最小二乘回归模型识别了驱动该生产力分布格局的环境因子。此外，本研究采用地理加权回归（GWR），探究了全陆架尺度下次级生产力与环境之间的区域异质性关联。研究发现，巴伦支海东北部季节性覆冰海域的大型底栖次级生产力显著高于常年无冰的西南部海域。与该分布格局显著相关的环境参数包括底层水温、盐度、海冰覆盖度、新生初级生产力、捕捞压力以及底层海流流速。结果表明，地理加权回归是分析底栖次级生产力与其环境驱动因子之间区域异质性关联的高效工具（决定系数R²=0.73）。该分布格局揭示了高生产力边缘冰区中，浮游与底栖生态系统之间存在紧密的浮游-底栖耦合（pelagic-benthic coupling）关系。当前冬季海冰覆盖范围持续缩减，加之季节性冰界线向极地方向迁移，预示着未来巴伦支海东北部的底栖次级生产力将出现显著下降。