Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA; Department of Earth, Environment and Life Sciences, University of Genoa, Genoa, Italy.
Department of Life Sciences, University of Trieste, Trieste, Italy.
Mar Environ Res. 2024 Nov;202:106718. doi: 10.1016/j.marenvres.2024.106718. Epub 2024 Aug 31.
Evidence of local and regional declines in the canopy-forming alga Ericaria amentacea, a foundation species of diverse marine forest communities on exposed Mediterranean coasts, have spurred restoration efforts focused on sustainable ex-situ techniques. The need to balance the costs of culture maintenance and the susceptibility of early life stages to stressors in the native habitat, including rapid, often extreme shifts in temperature, hydrodynamics and nutrient availability, have driven current efforts to create a culture environment that primes seedlings for outplant, increasing their resilience rather than maximizing growth. We tested the effects of 1) higher culture temperature (25 °C) combined with wave simulation and 2) reduced nutrient loads (10% of standard protocol) with wave simulation on post-culture and post-outplant outcomes relative to optimal growth conditions in established protocols (20 °C, no waves, high-nutrient culture medium). While increased temperature and water motion negatively affected seedling growth in culture, and higher nutrients caused oxidative stress likely associated with enhanced epiphyte overgrowth, these effects were not clearly translated into patterns of long-term growth in the field. Instead, survival in the initial days post-outplant appeared to be the bottleneck for restoration potential, where substrates with persisting seedlings at one month were generally found with flourishing juveniles at four months. Larger clumps of seedlings, in turn, were strongly associated with both initial survival and future growth. These results underscore the importance of the zygote settlement phase to establish high seedling densities, which may be optimized by phenological monitoring of the donor population. They also suggest that less-controlled, more environmentally-realistic culture conditions involving the introduction of mild stress may enhance the survival of early life stages of E. amentacea during the transition to the native environment, providing a means to simultaneously reduce human resource costs in culture and move toward scaling up.
在地中海暴露海岸的多样化海洋森林群落中，作为基础物种的树冠形成藻类 Ericaria amentacea 的局部和区域衰退的证据，已经促使人们关注集中于可持续的离体技术的恢复工作。维持培养物的成本和早期生命阶段对包括温度、水动力和营养物质可用性在内的原生境胁迫因素的敏感性之间需要取得平衡，这促使人们目前努力创造一种培养环境，为幼苗的移植做好准备，提高其适应能力，而不是最大限度地促进其生长。我们测试了以下两种方法的效果：1）更高的培养温度（25°C）结合波浪模拟，2）减少营养负荷（标准方案的 10%）结合波浪模拟，与既定方案中的最佳生长条件（20°C，无波浪，高营养培养基）相比，对培养后和移植后的结果产生影响。虽然温度升高和水动力运动对培养中的幼苗生长有负面影响，而较高的营养物质可能会导致与过度附生有关的氧化应激，但这些影响并没有明显转化为田间长期生长的模式。相反，移植后最初几天的存活率似乎是恢复潜力的瓶颈，在一个月内有持续幼苗的基质通常在四个月时会发现有茂盛的幼体。反过来，更大的幼苗团块与初始存活率和未来生长都密切相关。这些结果强调了受精卵着床阶段对于建立高幼苗密度的重要性，这可以通过对供体种群的物候监测来优化。它们还表明，涉及引入温和胁迫的、较少控制和更接近自然环境的培养条件可能会提高 E. amentacea 早期生命阶段在向原生境过渡期间的存活率，从而提供一种同时降低培养过程中的人力资源成本并逐步扩大规模的方法。
