Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain.
Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain.
Mar Environ Res. 2022 Jun;178:105647. doi: 10.1016/j.marenvres.2022.105647. Epub 2022 May 17.
Interactions among species are essential in shaping ecological communities, although it is not always clear under what conditions they can persist when the number of species involved is higher than two. Here we describe a three-species assemblage involving the seagrass Cymodocea nodosa, the pen shell Pinna nobilis and the herbivore sea urchin Paracentrotus lividus, and we explore the mechanisms allowing its persistence through field observations and manipulative experiments. The abundance of pen shells was higher in seagrass beds than in bare sand, suggesting a recruitment facilitation. The presence of sea urchins, almost exclusively attached or around pen shells, indicated habitat facilitation for sea urchins, which overgrazed the meadow around the pen shells forming seagrass-free halos. Our results suggest that this system persists thanks to: (i) the behavioral reluctance of sea urchins to move far from pen shells, making their impact on seagrass strictly local, (ii) the sparse distribution of pen shells and (iii) the plant's resistance mechanisms to herbivory. Unpacking these mechanisms allows a better understanding of how ecological communities are assembled.
物种间的相互作用对于塑造生态群落至关重要，但当涉及的物种数量超过两个时，它们在什么条件下能够持续存在并不总是清楚的。在这里，我们描述了一个涉及海草 C. nodosa、扇贝 P. nobilis 和食草性海胆 P. lividus 的三物种组合，并通过野外观察和操纵实验探索了允许其持续存在的机制。扇贝的丰度在海草草甸中高于裸沙，表明有促进其繁殖的作用。海胆的存在，几乎完全附着或围绕扇贝，表明海胆的栖息地得到了促进，它们过度放牧扇贝周围的草地，形成了无海草草甸的光环。我们的结果表明，这个系统之所以能够持续存在，是因为：（i）海胆不愿意远离扇贝，从而使其对海草的影响仅限于局部地区；（ii）扇贝的稀疏分布；以及（iii）植物对食草的抵抗机制。剖析这些机制可以更好地理解生态群落是如何组合的。
