ABSTRACT: Finfish aquaculture is playing an increasing role in global food provision, with accompanying increases in benthic impacts under intensive pen production systems. Deposited faeces under and near fish pens affect the seafloor environment and biogeochemical functioning. To maintain healthy coastal environments, many fish farms operate by alternating input and fallowing periods to allow benthic coastal receiving environments to recover from excess organic matter inputs. Here, we used flow-through annular flume mesocosms to simulate sustained organic matter inputs to the benthos with a subsequent fallowing period of no inputs. To quantify the effects of excess organic matter loading on benthic receiving environments, we carried out repeated closed-system flux studies to quantify the benthic carbon mineralisation processes, with a focus on benthic oxygen, inorganic and organic carbon, nitrogen, phosphate, and sulphide fluxes, along with the redox state throughout the input and recovery period. We found that recovery periods were input-dependent, with parameters requiring longer fallowing periods to recover following larger inputs. While some benthic parameter fluxes such as dissolved organic carbon, sulphide, and ammonium returned to their pre-input state relatively rapidly (1-2 mo) following cessation of inputs, others such as sediment oxygen demand, ammonium, and redox required longer (>7 mo) to recover. Our results suggest that in situations where the benthic macrofaunal community has been severely impaired, extended fallowing periods may be required in order to permit the biogeochemical composition of the seabed to return to a more natural state, with implications for farm-consenting permits and planning as well as operational fallowing practices.

中文翻译：

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模拟养鱼场的富集和休闲影响揭示了底栖变量的不平等生物地球化学恢复

摘要：有鳍鱼水产养殖在全球食品供应中发挥着越来越重要的作用，伴随着集约化围栏生产系统下底栖影响的增加。鱼圈下方和附近沉积的粪便会影响海底环境和生物地球化学功能。为了维持健康的沿海环境，许多养鱼场通过交替投入和休耕期来运营，以使底栖沿海接收环境从过量的有机物质投入中恢复过来。在这里，我们使用流经环形水槽中观系统来模拟持续向底栖生物输入有机物质，随后的休耕期没有输入。为了量化过量有机物负荷对底栖接收环境的影响，我们进行了重复的封闭系统通量研究，以量化底栖碳矿化过程，重点关注底栖氧、无机和有机碳、氮、磷酸盐和硫化物通量，以及整个输入和恢复期间的氧化还原状态。我们发现恢复期取决于输入，参数需要更长的休耕期才能在更大的输入后恢复。虽然一些底栖参数通量如溶解有机碳、硫化物和铵在输入停止后相对快速地（1-2 个月）恢复到输入前状态，但其他如沉积物需氧量、铵和氧化还原需要更长的时间（> 7 个月）恢复。我们的研究结果表明，在底栖大型动物群落严重受损的情况下，可能需要延长休耕期才能使海底的生物地球化学成分恢复到更自然的状态，