Biodiversity Research Centre, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
FEMS Microbiol Ecol. 2024 Aug 13;100(9). doi: 10.1093/femsec/fiae101.
The factors shaping host-parasite interactions and epibiont communities in the variable rocky intertidal zone are poorly understood. California mussels, Mytilus californianus, are colonized by endolithic cyanobacterial parasites that erode the host shell. These cyanobacteria become mutualistic under certain abiotic conditions because shell erosion can protect mussels from thermal stress. How parasitic shell erosion affects or is affected by epibiotic microbial communities on mussel shells and the context dependency of these interactions is unknown. We used transplant experiments to characterize assemblages of epibiotic bacteria and endolithic parasites on mussel shells across intertidal elevation gradients. We hypothesized that living mussels, and associated epibacterial communities, could limit colonization and erosion by endolithic cyanobacteria compared with empty mussel shells. We hypothesized that shell erosion would be associated with compositional shifts in the epibacterial community and tidal elevation. We found that living mussels experienced less shell erosion than empty shells, demonstrating potential biotic regulation of endolithic parasites. Increased shell erosion was not associated with a distinct epibacterial community and was decoupled from the relative abundance of putatively endolithic taxa. Our findings suggest that epibacterial community structure is not directly impacted by the dynamic symbiosis between endolithic cyanobacteria and mussels throughout the rocky intertidal zone.
宿主-寄生虫相互作用和附生生物群落的形成因素在多变的岩石潮间带中理解甚少。加利福尼亚贻贝（Mytilus californianus）被内共生蓝藻寄生虫所寄生，这些寄生虫会侵蚀宿主的贝壳。在某些非生物条件下，这些蓝藻会成为互利共生体，因为贝壳的侵蚀可以保护贻贝免受热应激的影响。寄生性贝壳侵蚀如何影响或受贻贝贝壳上附生微生物群落的影响，以及这些相互作用的背景依赖性尚不清楚。我们使用移植实验来描述贻贝贝壳上附生细菌和内共生寄生虫的组合。我们假设，活贻贝及其相关的附生细菌群落可能会限制内共生蓝藻的定殖和侵蚀，而空贻贝壳则不会。我们假设贝壳侵蚀与附生细菌群落的组成变化以及潮汐高度有关。我们发现，活贻贝的贝壳侵蚀程度低于空贝壳，这表明内共生寄生虫可能受到生物的调控。贝壳侵蚀的增加与独特的附生细菌群落无关，也与假定的内共生类群的相对丰度无关。我们的研究结果表明，在整个岩石潮间带，内共生蓝藻和贻贝之间的动态共生关系不会直接影响附生细菌群落的结构。
