Incorporation of colonization pressure into the propagule pressure-based global ballast water standard

In 2024 cargo vessels must meet the International Maritime Organization’s global ballast water discharge standards (IMO D-2) that limit the concentration of living organisms. D-2 focuses on reducing invasion risk by reducing ‘community propagule pressure (CPP)’, though it does not consider colonization pressure (CP). We modeled risk differences in IMO D-2-compliant discharges (10 ind. m-3) for communities that had inverse patterns of CP and species’ individual propagule pressures (IPP). Secondly, we determined the effect on risk of varying CPP and CP. As part of this we tested whether the IMO D-2 standard for zooplankton-sized organisms of &lt;10 individuals m-3 was an optimal choice. Risk was defined as probability of at least one species invading using four risk-release models. Risk differed strongly at the D-2 limit based on community composition. At low CPP (&lt;25 ind. m-3), risk was strongly affected by CP for hyperbolic and linear risk-release models and weakly for exponential an..., Data was collected through a mechanistic model. The model considered real-world Ballast water volumes from Bradie, Rolla, Bailey &amp; MacIsaac (2022), which consisted of 10000 recorded ballast water discharges that ranged from 20 to 1060620 m3 (13871 ± 25738, mean ± standard deviation). Using these volumes we then set community propagule pressure and colonization pressure while varying individual propagule pressure to determine the risk of the establishment (1 - risk of extinction). Next, we set individual propagule pressure, colonization pressure, and community propagule pressure and determined the risk of establishment. Each combination of community propagule pressure, individual propagule pressure, and colonization pressure was run for 100 iterations to simulate 100 trips. The risk of establishments per species across 100 trips was used to calculate the probability of at least one species establishing following Wonham, Byers, Grosholz &amp; Leung (2013). Additionally, the probabili..., All data files are provided in comma-separated value (.csv) format. Owing to the large file size, we recommend files be opened in statistical software (e.g. R, Python).2024年起，货船必须符合国际海事组织（International Maritime Organization, IMO）的全球压载水排放标准（IMO D-2），该标准对活体生物浓度作出了明确限制。D-2标准核心目标为通过降低「群落繁殖体压力（community propagule pressure, CPP）」以降低生物入侵风险，但该标准未考虑定殖压力（colonization pressure, CP）。 本研究针对定殖压力与物种个体繁殖体压力（individual propagule pressure, IPP）呈现反向分布规律的群落，模拟了符合IMO D-2标准（10 个·m⁻³）的压载水排放场景下的风险差异。其次，我们分析了CPP与CP变化对入侵风险的影响，并借此检验了针对浮游动物级生物的IMO D-2标准（≤10 个·m⁻³）是否为最优选择。 本研究以四种风险-释放模型（risk-release models）将入侵风险定义为「至少有一个物种成功入侵的概率」。研究发现，在D-2标准限值下，入侵风险因群落组成不同而存在显著差异。当CPP较低（<25 个·m⁻³）时，双曲线与线性风险-释放模型下的入侵风险受CP影响显著，而指数模型等的受影响程度较弱。 本研究数据通过机理模型生成。模型采用了Bradie、Rolla、Bailey与MacIsaac（2022）研究中的真实压载水体积数据，该数据集包含10000条压载水排放记录，体积范围为20至1060620 m³（均值±标准差：13871 ± 25738）。基于上述体积数据，我们通过调整个体繁殖体压力，设置群落繁殖体压力与定殖压力，以计算物种定殖风险（即1减去灭绝风险）。 随后，我们分别固定个体繁殖体压力、定殖压力与群落繁殖体压力，以确定定殖风险。群落繁殖体压力、个体繁殖体压力与定殖压力的每一种组合均运行100次迭代，以模拟100次航行航次。 基于100次航行中各物种的定殖风险，我们参照Wonham、Byers、Grosholz与Leung（2013）的研究方法，计算了至少有一个物种成功定殖的概率。此外，本研究的所有数据文件均以逗号分隔值（comma-separated value, .csv）格式提供。鉴于文件体积较大，建议使用统计软件（如R、Python）打开数据文件。