Will coral reef sponges be winners in the Anthropocene?
Will coral reef sponges be winners in the Anthropocene?
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DOI：
10.1111/gcb.15039
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发表时间：
2020-02
影响因子：
11.6
通讯作者：
M. Lesser;M. Slattery
中科院分区：
文献类型：
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作者：
M. Lesser;M. Slattery
最近的观察表明，与气候变化相关的珊瑚死亡率的增加导致浅层珊瑚礁群落结构的变化，通过相移到替代分类群。因此，海绵已经成为一个潜在的候选分类单元，成为“赢家”，因此在许多珊瑚礁群落中，海绵在数量和功能上都占据主导地位。但是，为了实现这一目标，必须有足够的营养资源来支持这些主动滤食性生物的大量繁殖。在全球范围内，气候变化正在引起海表温度（SSTs）的升高和盐度的降低，这可能导致近岸浅水（0-200米）的分层加剧，从而影响混合层深度（MLD）以及内波的强度和持续时间。具体而言，预计气候变化驱动的热带水域海温增加将导致分层增加，地表水更加稳定。这导致MLD变浅，从而阻止营养物质到达光带，预计到本世纪末将使净初级生产量（NPP）减少20%。随着水柱生产力与底栖生物之间的耦合减弱，较低的NPP随后会影响多个营养水平，包括浅层底栖滤食性群落。我们认为，气候变化实际上可能会限制而不是促进海绵种群的增长，因为由自下而上的强迫引起的初级营养资源的减少，次生于水体的物理变化（即，分层和MLD的变化导致营养物质和NPP的降低）。因此，我们预测海绵主导的热带珊瑚礁将是罕见的，或者是短暂的，如果它们在人类世的未来出现的话。
Recent observations have shown that increases in climate change‐related coral mortality cause changes in shallow coral reef community structure through phase shifts to alternative taxa. As a result, sponges have emerged as a potential candidate taxon to become a “winner,” and therefore a numerically and functionally dominant member of many coral reef communities. But, in order for this to occur, there must be sufficient trophic resources to support larger populations of these active filter‐feeding organisms. Globally, climate change is causing an increase in sea surface temperatures (SSTs) and a decrease in salinity, which can lead to an intensification in the stratification of shallow nearshore waters (0–200 m), that affects both the mixed layer depth (MLD) and the strength and duration of internal waves. Specifically, climate change‐driven increases in SSTs for tropical waters are predicted to cause increased stratification, and more stabilized surface waters. This causes a shallowing of the MLD which prevents nutrients from reaching the euphotic zone, and is predicted to decrease net primary production (NPP) up to 20% by the end of the century. Lower NPP would subsequently affect multiple trophic levels, including shallow benthic filter‐feeding communities, as the coupling between water column productivity and the benthos weakens. We argue here that sponge populations may actually be constrained, rather than promoted, by climate change due to decreases in their primary trophic resources, caused by bottom‐up forcing, secondary to physical changes in the water column (i.e., stratification and changes in the MLD resulting in lower nutrients and NPP). As a result, we predict sponge‐dominated tropical reefs will be rare, or short‐lived, if they occur at all into the future in the Anthropocene.