Vermeij Mark J A, Sandin Stuart A
Cooperative Institute for Marine and Atmospheric Studies, Rosenstiel School for Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA.
Ecology. 2008 Jul;89(7):1994-2004. doi: 10.1890/07-1296.1.
The local densities of heterospecifics and conspecifics are known to have profound effects on the dynamics of many benthic species, including rates of settlement and early post-settlement survivorship. We described the early life history of the Caribbean coral, Siderastrea radians by tracking the population dynamics from recently settled planulae to juveniles. Through three years of observation, settlement correlated with the abundance of other benthic organisms, principally turf algae (negatively) and crustose coralline algae (positively). In addition, adult density showed independent effects on coral settlement and early post-settlement survivorship. Settlement rates increased across low levels of adult cover and saturated at a maximum around 10% cover. Early post-settlement survivorship decreased with adult cover, revealing structuring density dependence in coral settlers. The earliest life stages of corals are defined by low survivorship, with survivorship increasing appreciably with colony size. However, recent settlers (one-polyp individuals, < 1-year-old) are more likely to grow into two-polyp juveniles than older single polyps (> 1-year-old) that were delayed in their development. The early benthic phase of corals is defined by a severe demographic bottleneck for S. radians, with appreciable density-dependent and density-independent effects on survivorship. For effective management and restoration of globally imperiled coral reefs, we must focus more attention on this little studied, but dynamic, early life history period of corals.
已知异种生物和同种生物的局部密度会对许多底栖生物的动态产生深远影响，包括附着率和附着后早期的存活率。我们通过追踪从刚附着的浮浪幼虫到幼体的种群动态，描述了加勒比珊瑚辐射鹿角珊瑚的早期生活史。经过三年的观察，附着与其他底栖生物的丰度相关，主要是丝状藻类（呈负相关）和壳状珊瑚藻（呈正相关）。此外，成体密度对珊瑚附着和附着后早期存活率有独立影响。附着率在成体覆盖率较低时增加，并在覆盖率达到约10%时达到饱和。附着后早期存活率随成体覆盖率降低，这揭示了珊瑚定居者中存在结构密度依赖性。珊瑚最早的生命阶段以低存活率为特征，存活率随着群体大小的增加而显著提高。然而，最近定居的个体（单息肉个体，<1岁）比发育延迟的较老单息肉个体（>1岁）更有可能成长为双息肉幼体。鹿角珊瑚的早期底栖阶段存在严重的种群瓶颈，对存活率有明显的密度依赖性和非密度依赖性影响。为了有效管理和恢复全球濒危的珊瑚礁，我们必须更多地关注珊瑚这个研究较少但动态变化的早期生活史阶段。
