Understanding the effects of bottom-trawling induced changes in benthic community structure, diversity and ecosystem functioning across different benthic-size components is imperative to determine the future sustainability of bottom-trawling fisheries in deep-sea regions. In this study, we combined field sampling observations with a pulse-chase experiment on sediments obtained from two stations of interest along the West Iberian Margin (WIM) distinguished by different trawling pressures. We compared these two stations in terms of meio- and macrofauna (infauna) standing stocks, biodiversity and several ecosystem function proxies. These proxies included: (i) 13C uptake by bacterial communities, (ii) infauna respiration rates, (iii) penetration of 13C in the sediment, and (iv) sediment pore-water nutrient concentrations. The pulse-chase experimental results were complemented with a larger biological dataset partially compiled from previous studies in the area, to investigate structural and functional diversity ecosystem functioning (respiration) patterns across the WIM. Our observations indicated that different regimes of trawling pressure influenced both macrofaunal respiration rates with disturbed sediments predominantly composed of deposit-/detritus-feeding smaller-sized macrofauna species. Moreover, sediment biogeochemical functioning (ammonium profiles) and 13C bacterial uptake showed differences among the two disturbance regimes. On the contrary, the biomass of small-sized biota, including bacteria and meiofauna, did not show marked differences between stations. The general depletion in macrofauna species richness across impacted areas of the study region was also correlated with a reduction in total biomass and respiration, suggesting that the long history of trawling disturbance at the WIM may affect regulatory ecosystem functions. These preliminary findings alert for the impacts of trawling on crucial functions of benthic ecosystems that may be imperceptible to the current tools used in monitoring programs.

中文翻译：

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底拖网干扰影响下的生态系统功能：西伊比利亚边缘大陆坡区的实验方法和现场观测

了解底拖网捕捞引起的不同底栖规模组成部分的底栖群落结构、多样性和生态系统功能变化的影响对于确定深海区域底拖网渔业未来的可持续性至关重要。在这项研究中，我们将现场采样观测与脉冲追踪实验相结合，对从西伊比利亚边缘 (WIM) 沿线的两个感兴趣的站点获得的沉积物进行了脉冲追踪实验，以不同的拖网压力区分。我们在小型和大型动物 (infauna) 常备种群、生物多样性和几个生态系统功能代理方面比较了这两个站点。这些代表包括：(i) 细菌群落对 13C 的吸收，(ii) 动物群呼吸速率，(iii) 13C 在沉积物中的渗透，以及 (iv) 沉积物孔隙水养分浓度。脉冲追踪实验结果辅以更大的生物数据集，该数据集部分来自该地区先前的研究，以研究整个 WIM 的结构和功能多样性生态系统功能（呼吸）模式。我们的观察表明，不同的拖网压力制度影响了大型动物的呼吸速率，扰动的沉积物主要由以沉积物/碎屑为食的小型大型动物物种组成。此外，沉积物生物地球化学功能（铵谱）和 13C 细菌吸收显示出两种干扰机制之间的差异。相反，小型生物群（包括细菌和小型动物）的生物量在站点之间没有表现出显着差异。研究区域受影响地区大型动物物种丰富度的普遍枯竭也与总生物量和呼吸作用的减少有关，这表明 WIM 拖网捕捞扰乱的悠久历史可能会影响监管生态系统功能。这些初步发现提醒人们注意拖网捕捞对底栖生态系统关键功能的影响，而这些影响可能是目前监测项目中使用的工具无法察觉的。