How Oyster Health Indices Vary between Mass Mortality Events
How Oyster Health Indices Vary between Mass Mortality Events
复制标题
大规模死亡事件之间的牡蛎健康指数如何变化
DOI：
10.2983/035.039.0308
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发表时间：
2020
影响因子：
1.3
通讯作者：
K. Kuykendall
中科院分区：
文献类型：
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作者：
Sara M. Pace;E. Powell;T. Soniat;K. Kuykendall
2016年和2019年发生的两次影响密西西比湾东部牡蛎的大规模死亡事件，使得研究人员能够调查种群在崩溃和从能够产生局部灭绝的系统性压力中恢复的动态。在这项研究中，指标被报告为真实的人口指标，其值与人口中大小类别的代表性成比例。该方法至关重要，因为Dermo患病率和加权患病率的趋势在大小类别之间存在很大差异，这允许阐明从整体人群中不明显的恢复轨迹。将人群划分为较大和较小的类别，在Dermo患病率和加权患病率的时间序列中显示出一致的差异；在2016年和2019年死亡事件之间的两年时间里，这些指标没有恢复到2016年死亡事件之前观察到的水平，特别是在较小规模的人群中，患病率仍然很低。由于种群向最初未感染的较小动物的大小频率发生实质性变化而导致的真皮感染返回的时间延迟与真皮和幼牡蛎细胞加倍时间的差异以及发生传播所需的时间延迟（尽管相对较短）是一致的。性腺厚度与病情指数基本一致，并遵循预期的季节周期；2016年死亡事件对这些指标的任何影响似乎都是无关紧要的。内收肌直径与壳高度之间的关系在时间序列上变化不大，比内收肌直径与壳重之间的关系稳定得多，表明2016年后牡蛎壳形状发生了变化。由此推断，在三个指标中，壳重对健康指标的估计和其他健康指标的标准化变化较大。建立特定大小类别和整体种群的健康指标的能力对于理解严重压力源或死亡事件对牡蛎种群的时间影响至关重要。
ABSTRACT Two mass mortality events in 2016 and 2019 affecting the eastern oyster in the Mississippi Sound permitted an investigation of population dynamics during the collapse and recovery from systemic stressors capable of producing local extinction. In this study, metrics were reported as true population metrics with values included in proportion to the size class representation in the population. The approach was critical as trends in Dermo prevalence and weighted prevalence varied substantially between size classes, and this permitted elucidation of recovery trajectories not obvious from the population as a whole. The division of the population into larger and smaller size classes revealed a consistent differential in the time series for Dermo prevalence and weighted prevalence; these metrics did not return to levels observed before the 2016 mortality event in the 2-y interim between the 2016 and 2019 mortality events, and prevalence, in particular, remained low in the smaller size class. The time delay in the return of Dermo infection due to a substantial change in the size frequency of the population toward smaller initially uninfected animals is consistent with the differential in Dermo and young oyster cell doubling times and the required time delay, albeit relatively short, for transmission to occur. Gonadal thickness generally tracked with condition index and followed the expected seasonal cycle; any impact resulting from the 2016 mortality event on these metrics appeared to be inconsequential. The relationship between the adductor muscle diameter and shell height varied little over the time series and was much more stable than between the adductor muscle diameter and shell weight, suggesting a change in the oyster shell shape post-2016. By inference, shell weight is more variable among the three metrics in estimation of the condition index and standardization of other health indices. The ability to establish health metrics for both specific size classes and the population as a whole is essential to understanding the temporal impacts of a severe stressor or mortality event on oyster populations.