How successive meteotsunami and storm activity disrupts saltmarsh vegetation

Meteotsunami (meteorological tsunami) are globally occurring progressive shallow water waves with a period of between 2 and 120 minutes which result from sudden pressure changes and wind stress due to moving atmospheric systems. These waves are known to cause destruction to and loss of assets. Currently, there is no research into the impact of meteotsunami on coastal ecosystems such as saltmarshes, despite the significant role saltmarsh play in providing vital habitats for resident and migrating birds, natural flood defences and climate mitigation. As such the restoration of saltmarshes has emerged as a pivotal focus within the UK Government’s environmental policy framework. This paper examines the impact of two meteotsunami events (2016 and 2021) on saltmarsh vegetation in the southwestern UK. An assessment of the vegetation pre and post event was undertaken using high resolution satellite imagery and the Normalised Difference Vegetation Index (NDVI). Results revealed that the 2016 meteotsunami exacted minimal vegetation change with a decrease in NDVI from 0.26 to 0.23 and a temporary reduction in coverage of 40%, suggesting a potential resilience to single episodic disturbances. In contrast, the 2021 event, compounded by multiple significant storms and additional meteotsunami, led to a decline in NDVI values from 0.44 to 0.22 and a temporary reduction in vegetation coverage of 66%. Both events indicated a short-term disruption with a relatively rapid rebound (within one to three months). However, the longer-term effects of such a disruption on the saltmarsh ecosystem need to be investigated further. This comparative analysis underscores the complex interactions between meteotsunami, climatic phenomena, and coastal vegetation dynamics, highlighting the necessity for ongoing monitoring and research to understand the resilience mechanisms of such ecosystems in the face of increasing climatic variability and extreme weather events.