Determining how functionally diverse intertidal sediment species preserve mudflat ecosystem properties after abrupt biodiversity loss

As a result of anthropogenic climate change, extreme climatic events have increased in frequency, severity, and longevity. The consequences for community structure after a catastrophic event have been well studied. However, changes in ecosystem functioning that occur after such an event, including ecosystemrecovery, are still uncertain. A catastrophic event was simulated in an intertidalsedimentary habitat. Postevent sediment replicates were assigned to one of four recovery scenarios: (1) no recovery, (2) migration recovery, and recovery by differential opportunistic colonisation by (3) the polychaete worm Hediste diversicolor and (4) the mud snail Peringia ulvae, two locally dominant infauna species. These are compared with a control scenario not subjected to the event. The simulated extreme event caused a shift in habitat state due to a reduction in mobile macrofauna abundance and an increase in microphytobenthos biomass. Migratory recovery of species and the simulated opportunistic expansion of a single species ameliorated this shift and, for some metrics, functional compensation for the loss of other species and the preservation of certain ecosystem functions was observed. The dominant species identity during postevent habitat recovery can have considerable effects on important ecosystem processes and functions with consequences that may result in functional regime shifts in a habitat and alter coastal stability.