Effects of Seagrass Wasting Disease on Eelgrass Growth and Belowground Sugar in Natural Meadows
Effects of Seagrass Wasting Disease on Eelgrass Growth and Belowground Sugar in Natural Meadows
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DOI：
10.3389/fmars.2021.768668
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发表时间：
2021-11
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影响因子：
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通讯作者：
S. Trevathan‐Tackett;Olivia J. Graham;Lillian R. Aoki;Tiffany A. Stephens;Joshua T. Stokes;Sukanya Dayal;B. Rappazzo;Carla Gomes;Drew Harvell
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作者：
S. Trevathan‐Tackett;Olivia J. Graham;Lillian R. Aoki;Tiffany A. Stephens;Joshua T. Stokes;Sukanya Dayal;B. Rappazzo;Carla Gomes;Drew Harvell
海草草甸提供了宝贵的生态系统效益，但面临疾病风险。鳗草（Zostera marina）是一种温带物种，受到由原生生物 Labyrinthula zosterae 引起的海草消耗病 (SWD) 的威胁。该病原体对海洋温度升高敏感，因此需要更好地了解气候变化对宿主健康的影响。先前的工作表明，病原体培养物在较温暖的实验室条件下生长得更快，并记录了较温暖的海洋温度与自然界疾病水平之间的正相关性。然而，疾病爆发对鳗草生长的影响仍然知之甚少。在这里，我们研究了疾病对田间鳗草生产力的影响。我们将原位芽标记与鳗草叶片的高分辨率图像结合起来，并使用人工智能应用程序从数字图像中确定疾病的患病率和严重程度。鳗草生长和疾病指标的比较表明，SWD 损害了鳗草生长和田间非结构碳的积累。患有更严重疾病的叶片生长速度降低，表明疾病严重程度会限制植物生长。疾病严重程度和根茎糖含量也呈负相关，表明疾病减少了地下碳积累。最后，对患病叶片的重复测量表明，病变部位的生长速度比原位健康组织生长得更快。这是第一项证明消耗性疾病对天然草地中的鳗草健康产生负面影响的研究。这些结果强调了将疾病与其他压力因素一起考虑的重要性，以更好地预测人类世海草草甸的健康和功能。
Seagrass meadows provide valuable ecosystem benefits but are at risk from disease. Eelgrass (Zostera marina) is a temperate species threatened by seagrass wasting disease (SWD), caused by the protist Labyrinthula zosterae. The pathogen is sensitive to warming ocean temperatures, prompting a need for greater understanding of the impacts on host health under climate change. Previous work demonstrates pathogen cultures grow faster under warmer laboratory conditions and documents positive correlations between warmer ocean temperatures and disease levels in nature. However, the consequences of disease outbreaks on eelgrass growth remain poorly understood. Here, we examined the effect of disease on eelgrass productivity in the field. We coupled in situ shoot marking with high-resolution imagery of eelgrass blades and used an artificial intelligence application to determine disease prevalence and severity from digital images. Comparisons of eelgrass growth and disease metrics showed that SWD impaired eelgrass growth and accumulation of non-structural carbon in the field. Blades with more severe disease had reduced growth rates, indicating that disease severity can limit plant growth. Disease severity and rhizome sugar content were also inversely related, suggesting that disease reduced belowground carbon accumulation. Finally, repeated measurements of diseased blades indicated that lesions can grow faster than healthy tissue in situ. This is the first study to demonstrate the negative impact of wasting disease on eelgrass health in a natural meadow. These results emphasize the importance of considering disease alongside other stressors to better predict the health and functioning of seagrass meadows in the Anthropocene.