Mesophotic coral refuges following multiple disturbances
Mesophotic coral refuges following multiple disturbances
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DOI：
10.1007/s00338-021-02087-w
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发表时间：
2021-04-03
期刊：
影响因子：
3.5
通讯作者：
Holstein, Daniel M.
中科院分区：
文献类型：
--
作者：
Bloomberg, Jeanne;Holstein, Daniel M.
随着全球浅礁珊瑚种群数量的减少，中温珊瑚生态系统(MCE)被认为是面对气候变化时潜在的珊瑚避难所，可以躲避热、风暴和人为干扰。目前的研究评估了美属维尔京群岛(USVI)的MCEs对Montastraea cavernosa的庇护潜力，方法是通过区域风暴、疾病和漂白扰动后的深度分层珊瑚损失来推断繁殖潜力。从组织学上测量了这种深度通用性珊瑚从4米到40米的繁殖力，然后在物种的深度范围内外推了息肉、种群和总的栖息地繁殖力。每条息肉的生殖活跃雌性性腺的数量和卵母细胞的大小随着深度的增加而显著减少，尽管很小，可能是由于能量的限制。值得注意的是，浅层和中层珊瑚礁的种群性别比与1：1没有区别，但在中层珊瑚礁变得明显偏向男性(3.6：1)。种群水平上的卵母细胞产量在深度上的差异主要是由珊瑚覆盖率和性别比例的变化驱动的。USVI中层生物礁相对于浅层生物礁的较大空间范围使MCEs成为卵母细胞的主要贡献者，尽管在深海雌性生物的比例减少。继2017年伊尔玛和玛丽亚飓风、2019年石珊瑚组织损失病爆发和2019年白化事件之后，浅海和中深海绵种群经历了珊瑚盖度的严重下降。浅层和中层种群繁殖力预计将相应下降。在这些主要是浅水扰动之后，MCEs的珊瑚覆盖率保持相对稳定，预测的种群数量和总的栖息地繁殖力也保持不变。因此，USVI的MCEs目前似乎是海绵虫的繁殖避难所，但随着疾病扰动开始影响更深的珊瑚礁，这种避难所的持久性仍然存在疑问。
As coral populations on shallow reefs decline globally, mesophotic coral ecosystems (MCE) have been proposed as potential coral refugia from thermal, storm, and anthropogenic disturbances in the face of climate change. The current study assesses the refuge potential of MCEs in the U.S. Virgin Islands (USVI) for Montastraea cavernosa by extrapolating reproductive potential through depth-stratified coral loss following regional storm, disease, and bleaching perturbations. Fecundity of this depth-generalist coral from 4 to 40 m was measured histologically, and polyp, population, and total habitat fecundities were then extrapolated across the species' depth range. The number of reproductively active female gonads per polyp and oocyte size experienced a significant, though small, decrease with depth, potentially due to energetic limitations. Notably, the population sex ratio was not different from 1:1 on shallow and mid-depth reefs, but it became significantly male-biased (3.6:1) at mesophotic depths. Population-level differences in oocyte production over depth were primarily driven by changes in coral cover and sex ratio. The large spatial extent of mesophotic reefs relative to shallow reefs in the USVI makes MCEs the primary contributor of oocytes, despite the reduced proportion of females at depth. Following Hurricanes Irma and Maria in 2017, the outbreak of Stony Coral Tissue Loss Disease in 2019, and a bleaching event in 2019, shallow and mid-depth M. cavernosa populations experienced severe coral cover declines. Shallow and mid-depth population fecundities were predicted to decline correspondingly. Coral cover in MCEs remained relatively stable following these largely shallow water perturbations, and predicted population and total habitat fecundities remained constant as well. Thus, MCEs in the USVI currently appear to be reproductive refuges for M. cavernosa, but the persistence of that refuge remains in question as disease perturbation begins to affect deeper reefs.