Data from: Mollusc-shell debris can mitigate the deleterious effects of organic pollution on marine sediments

1. Organic pollution is widespread in coastal areas and can have profound impacts on the seabed. Coastal sediments play an important role at a global scale in the recycling of organic matter, and this process is influenced by the habitat complexity of the sediments, among other factors. Mollusc shells are produced as a waste product from a range of anthropogenic activities, but we demonstrate that they can be used to increase the habitat complexity of sediments.
2. We studied the effect of mussel-shell debris (shell-hash) on the biogeochemical processes of marine sediments affected by organic pollution, using a mesocosm experiment simulating the bioturbation effects of macrofauna.
3. We found that shell-hash improved the ecological status of organically-polluted sediments by reducing the accumulation of sulphide from anaerobic metabolic pathways.
4. Additionally, when shell-hash was present in an organically-polluted sediment, there was a decrease in ammonium release to the water column, thus preventing the negative ecological consequences of eutrophication.
5. Synthesis and applications: Our study indicates that shell-hash debris can be used as a potential tool to mitigate the effects of organic enrichment on marine sediments. A density of shell-hash debris of 1,900 g·m-2 in the sediment can diminish toxic by-products (sulphides and ammonium) derived from the stimulation of anaerobic metabolic pathways by organic pollution, at levels that are biologically relevant. The mitigation effect of shell-hash is more pronounced in sediments where macrofauna is not present.

1. 有机污染在沿海区域广泛分布，可对海底生态系统造成深远影响。沿海沉积物在全球尺度的有机质循环过程中扮演着核心角色，而该过程受沉积物栖息地复杂度（habitat complexity）等诸多因素调控。软体动物贝壳（mollusc shell）是多类人为活动（anthropogenic activity）产生的废弃物，但本研究证实其可用于提升沉积物的栖息地复杂度。
2. 本研究通过模拟大型底栖动物（macrofauna）生物扰动效应的中宇宙实验（mesocosm experiment），探究了贻贝贝壳碎屑（shell-hash）对受有机污染的海洋沉积物生物地球化学过程（biogeochemical process）的调控作用。
3. 研究结果显示，贝壳碎屑可通过抑制厌氧代谢途径产生的硫化物积累，改善受有机污染沉积物的生态健康状态。
4. 此外，当受有机污染的沉积物中存在贝壳碎屑时，向水柱（water column）释放的铵（ammonium）浓度会显著降低，从而规避富营养化（eutrophication）引发的负面生态后果。
5. 综合与应用：本研究表明，贝壳碎屑可作为潜在修复工具，用以缓解海洋沉积物的有机质富集（organic enrichment）效应。当沉积物中贝壳碎屑投放密度为1900 g·m⁻²时，可将有机污染刺激厌氧代谢途径所产生的有毒副产物（toxic by-product，涵盖硫化物与铵）降至具有生物学意义的安全水平。且在无大型底栖动物栖息的沉积物中，贝壳碎屑的生态修复效果更为突出。