Inundation characteristics of mangrove and saltmarsh in micro-tidal estuaries

Abstract Tidal inundation is a principal driver in intertidal wetland functioning. A combination of surface elevation and its relation to tidal range creates inundation regimes that influence a range of abiotic factors that affect wetland species distribution. Hydroperiod is a term frequently used to describe inundation regimes; however, the term has been vaguely defined in the past and typically quantified using tide gauge data rather than empirical field observations. This study explores relationships between various characteristics, such as frequency, total duration, average duration, average depth, non-tidal exposure, and mangrove/saltmarsh distribution in micro-tidal estuarine settings of southeast Australia. Inundation was measured directly using 35 pressure transducers embedded into mangrove and saltmarsh substrates over a period of two lunar tidal cycles along six transects located at Clyde and Minnamurra River estuaries, New South Wales, Australia. Results indicated differences in wetland inundation characteristics between mangrove and saltmarsh that are a function of wetland microtopography and site-specific tidal regime (e.g. local tidal range). For example, mangroves were inundated approximately 15–70% of the time, and 0.9–2 times a day, whereas saltmarshes were submerged only