Interpreting intertidal invasions
In: Nature Ecology & Evolution. Springer Nature. ISSN 2397-334X, more
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| Abstract |
While some effects of invasive species on native species are direct and immediately evident, others are more indirect and difficult to observe. Writing in the Proceedings of the National Academy of Sciences, Wang and colleagues document complex effects of an invasive cordgrass, Spartina alterniflora, on a native intertidal species, Suaeda salsa, on the Yellow Sea coast of China. S. salsa is iconic in the region because it is bright red and its growth in the tidal flats serves as crucial stopover sites for migrating birds. Remote sensing data from 1982 to 2020 show that Suaeda salsa has dramatically declined; the authors develop and test a theoretical model to explain the decline. They show that Spartina alterniflora, which grows closest to the sea, builds up a sediment ridge that prevents seawater inundation and alters the salinity gradient further inshore. This reduced salinity improves the performance of Phragmites australis, a native reed species that flanks the Suaeda salsa zone on the inland side, ultimately squeezing Suaeda salsa into just a narrow zone of the intertidal. Beyond explaining the enigmatic decline of a charismatic species, the results exemplify how an invader can cause declines in a native species by way of facilitation from afar. |
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