Contrasting strategies to cope with storm-induced erosion events: a flume study comparing a native vs. introduced bivalve

Storm-induced erosion events may alter the diversity of tidal flat communities by selecting species that can better tolerate such disturbances. Introduced and invasive species are highly adaptable to a wide range of abiotic characteristics, and this adaptability may make them better able to withstand erosion events. With a novel flume method, we compared the ability of two bivalve species to resist storm-induced erosion: Cerastoderma edule, a native species to the Scheldt estuary in the Netherlands, and Ruditapes philippinarum, an introduced species that is successful in the Netherlands and worldwide. We used three sediment erosion rates to simulate storms of increasing severity. At the 10.6 and 15.9 cm h⁻¹ sediment erosion rates, all R. philippinarum were surfaced, whereas only half C. edule were surfaced. However, after being brought to the sediment surface, C. edule were more readily transported by currents and waves than R. philippinarum due to differences in their shell shape. We concluded that the two bivalve species had different strategies to avoid mortality by severe storm erosion: C. edule avoided being surfaced and R. philippinarum avoided being transported. In this case, it appears that extreme storms favor the specific adaptations of a native species over the broad adaptability of a non-indigenous one. Indeed, C. edule may be more likely to survive moderately extreme storms than R. philippinarum, though the most extreme storms would be equally devastating to both species.