Hale Rachel, Godbold Jasmin A, Sciberras Marija, Dwight Jessica, Wood Christina, Hiddink Jan G, Solan Martin
1School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton Waterfront Campus, European Way, Southampton, SO14 3ZH UK.
2Biological Sciences,Faculty of Natural and Environmental Sciences, University of Southampton, Highfield Campus, Life Sciences Building 85, Southampton, SO17 1BJ UK.
Biogeochemistry. 2017;135(1):121-133. doi: 10.1007/s10533-017-0350-9. Epub 2017 Jun 12.
Benthic communities play a major role in organic matter remineralisation and the mediation of many aspects of shelf sea biogeochemistry. Few studies have considered how changes in community structure associated with different levels of physical disturbance affect sediment macronutrients and carbon following the cessation of disturbance. Here, we investigate how faunal activity (sediment particle reworking and bioirrigation) in communities that have survived contrasting levels of bottom fishing affect sediment organic carbon content and macronutrient concentrations ([NH-N], [NO-N], [NO-N], [PO-P], [SiO-Si]). We find that organic carbon content and [NO-N] decline in cohesive sediment communities that have experienced an increased frequency of fishing, whilst [NH-N], [NO-N], [PO-P] and [SiO-Si] are not affected. [NH-N] increases in non-cohesive sediments that have experienced a higher frequency of fishing. Further analyses reveal that the way communities are restructured by physical disturbance differs between sediment type and with fishing frequency, but that changes in community structure do little to affect bioturbation and associated levels of organic carbon and nutrient concentrations. Our results suggest that in the presence of physical disturbance, irrespective of sediment type, the mediation of macronutrient and carbon cycling increasingly reflects the decoupling of organism-sediment relations. Indeed, it is the traits of the species that reside at the sediment-water interface, or that occupy deeper parts of the sediment profile, that are disproportionately expressed post-disturbance, that are most important for sustaining biogeochemical functioning.
底栖生物群落对有机物质的再矿化以及陆架海生物地球化学诸多方面的调节起着重要作用。很少有研究考虑与不同程度物理干扰相关的群落结构变化在干扰停止后如何影响沉积物中的大量营养素和碳。在此，我们研究了在经历了不同程度底拖网捕捞的群落中，动物活动（沉积物颗粒再加工和生物灌溉）如何影响沉积物有机碳含量和大量营养素浓度（[NH₄⁺-N]、[NO₂⁻-N]、[NO₃⁻-N]、[PO₄³⁻-P]、[SiO₃²⁻-Si]）。我们发现，在经历捕捞频率增加的粘性沉积物群落中，有机碳含量和[NO₃⁻-N]下降，而[NH₄⁺-N]、[NO₂⁻-N]、[PO₄³⁻-P]和[SiO₃²⁻-Si]不受影响。在经历更高捕捞频率的非粘性沉积物中，[NH₄⁺-N]增加。进一步分析表明，物理干扰对群落结构的重组方式因沉积物类型和捕捞频率而异，但群落结构的变化对生物扰动以及相关的有机碳和营养素浓度水平影响不大。我们的结果表明，在存在物理干扰的情况下，无论沉积物类型如何，大量营养素和碳循环的调节越来越多地反映出生物与沉积物关系的解耦。事实上，对于维持生物地球化学功能而言，最重要的是那些栖息在沉积物 - 水界面或占据沉积物剖面较深部分的物种的特征，这些特征在干扰后会过度表达。
