Umanzor Schery, Ladah Lydia, Zertuche-González José A
Department of Marine Ecology, CICESE, Carretera Ensenada-Tijuana #3918, Zona Playitas, Ensenada, Baja California, CP 22860, Mexico.
Department of Biological Oceanography, CICESE, Carretera Ensenada-Tijuana #3918, Zona Playitas, Ensenada, Baja California, CP 22860, Mexico.
J Phycol. 2017 Oct;53(5):1060-1071. doi: 10.1111/jpy.12565. Epub 2017 Aug 30.
Intertidal macroalgae can modulate their biophysical environment by ameliorating physical conditions and creating habitats. Exploring how seaweed aggregations made up of different species at different densities modify the local environment may help explain how associated organisms respond to the attenuation of extreme physical conditions. Using Silvetia compressa, Chondracanthus canaliculatus, and Pyropia perforata, we constructed monocultures representing the leathery, corticated and foliose functional forms as well as a mixed tri-culture assemblage including the former three, at four densities. Treatment quadrats were installed in the intertidal where we measured irradiance, temperature, particle retention, and water motion underneath the canopies. Additionally, we examined the abundance and richness of the understory microphytobenthos with settlement slides. We found that the density and species composition of the assemblages modulated the amelioration of extreme physical conditions, with macroalgal aggregations of greater structural complexity due to their form and density showing greater physical factor attenuation. However, increasing the number of species within a patch did not directly result in increased complexity and therefore, did not necessarily cause greater amelioration of the environment. Microphytobenthic composition was also affected by species composition and density, with higher abundances under S. compressa and C. canaliculatus canopies at high and mid densities. These results support the idea that the environmental modifications driven by these macroalgae have a significant effect on the dynamics of the intertidal environment by promoting distinct temporal and spatial patchiness in the microphytobenthos, with potentially significant effects on the overall productivity of these ecosystems.
潮间带大型藻类可以通过改善物理条件和创造栖息地来调节其生物物理环境。探索由不同物种、不同密度组成的海藻聚集体如何改变当地环境，可能有助于解释相关生物如何应对极端物理条件的减弱。我们使用皱波石莼、管孔软骨藻和穿孔紫菜，构建了代表革质、皮层状和叶状功能形态的单种培养物，以及包括前三种藻类的混合三物种培养组合，设置了四种密度。将处理样方安装在潮间带，在那里我们测量了树冠层下方的辐照度、温度、颗粒滞留和水流运动。此外，我们用沉降载玻片检查了林下微型底栖植物的丰度和丰富度。我们发现，聚集体的密度和物种组成调节了极端物理条件的改善，由于其形态和密度导致结构更复杂的大型海藻聚集体对物理因素的衰减作用更大。然而，增加斑块内的物种数量并不会直接导致复杂性增加，因此，不一定会带来更大程度的环境改善。微型底栖植物的组成也受到物种组成和密度的影响，在高密度和中密度下，皱波石莼和管孔软骨藻树冠层下的丰度较高。这些结果支持了这样一种观点，即这些大型藻类驱动的环境变化通过促进微型底栖植物中不同的时间和空间斑块化，对潮间带环境动态产生重大影响，对这些生态系统的整体生产力可能产生重大影响。
