McLaren Emily, Sommer Brigitte, Pandolfi John M, Beger Maria, Byrne Maria
School of Life and Environmental Sciences, Coastal and Marine Ecosystems Group The University of Sydney Sydney New South Wales Australia.
School of the Environment The University of Queensland St. Lucia Queensland Australia.
Ecol Evol. 2024 May 19;14(5):e11412. doi: 10.1002/ece3.11412. eCollection 2024 May.
Subtropical reefs host a dynamic mix of tropical, subtropical, and temperate species that is changing due to shifts in the abundance and distribution of species in response to ocean warming. In these transitional communities, biogeographic affinity is expected to predict changes in species composition, with projected increases of tropical species and declines in cool-affinity temperate species. Understanding population dynamics of species along biogeographic transition zones is critical, especially for habitat engineers such as sea urchins that can facilitate ecosystem shifts through grazing. We investigated the population dynamics of sea urchins on coral-associated subtropical reefs at 7 sites in eastern Australia (28.196° S to 30.95° S) over 9 years (2010-2019), a period impacted by warming and heatwaves. Specifically, we investigated the density and population size structure of taxa with temperate (), subtropical () and tropical ( spp.) affinities. Counter to expectation, biogeographic affinity did not explain shifts in species abundances in this region. Although we expected the abundance of tropical species to increase at their cold range boundaries, tropical species declined across all sites. The subtropical also showed declines, while populations of the temperate were remarkably stable throughout our study period. Our results show that temporal patterns of sea urchin populations in this region cannot be predicted by bio-geographic affinity alone and contribute critical information about the population dynamics of these important herbivores along this biogeographic transition zone.
亚热带珊瑚礁拥有热带、亚热带和温带物种的动态组合，由于物种的丰度和分布因海洋变暖而发生变化，这种组合正在改变。在这些过渡群落中，生物地理亲缘关系有望预测物种组成的变化，预计热带物种会增加，而与凉爽环境相关的温带物种会减少。了解生物地理过渡带沿线物种的种群动态至关重要，特别是对于像海胆这样的栖息地改造者，它们可以通过啃食促进生态系统的转变。我们在9年时间里（2010 - 2019年）对澳大利亚东部7个地点（南纬28.196°至30.95°）与珊瑚相关的亚热带珊瑚礁上的海胆种群动态进行了调查，这一时期受到变暖和热浪的影响。具体来说，我们调查了具有温带（）、亚热带（）和热带（ spp.）亲缘关系的分类群的密度和种群大小结构。与预期相反，生物地理亲缘关系并不能解释该地区物种丰度的变化。尽管我们预计热带物种在其寒冷范围边界处的丰度会增加，但热带 物种在所有地点都减少了。亚热带 也呈现下降趋势，而温带 的种群在我们的研究期间一直非常稳定。我们的结果表明，该地区海胆种群的时间模式不能仅通过生物地理亲缘关系来预测，并且为这条生物地理过渡带沿线这些重要食草动物的种群动态提供了关键信息。
