Effects of Extreme Salinity Stress on a Temperate Mangrove Ecosystem

Mangrove forests provide essential ecosystem services, but are threatened by habitat loss, effects of climatic change and chemical pollutants. Hypersalinity can also lead to mangrove mortality, although mangroves adapted saline habitats. A recent dieback event >9 ha temperate ( Avicennia marina ) in South Australia allowed evaluate the generality anthropogenic impacts on ecosystems. We carried out multidisciplinary investigations, combining airborne remote sensing with on-ground measurements detect extent impact. The forest was differentiated into “healthy,” “stressed,” “dead” zones using LIDAR, RGB hyperspectral imagery. Differences characteristics trees soils were tested between these zones. Porewater salinities >100 measured areas where occurred, hypersalinity persisted a year after event, making it one most extreme cases known mangrove. Sediments zone anaerobic contained higher concentrations sulfate chloride. CO 2 efflux from sediment as well carbon stocks biomass soil did not differ event. photosynthetic traits physiological indicated that health impacted beyond immediate zone. Normalized Difference Vegetation Index (NDVI), rate, stomatal conductance transpiration rate chlorophyll fluorescence lower “stressed” than “healthy” Leaves less nitrogen phosphorous leaves zone, had arsenic, sulfur zinc concentrations. response semi-arid similar sub-/tropical climates already at their tolerance limit, which places them more risk regardless latitude. findings have relevance for understanding disturbance mangrove, added significance climate regions could expand global warming.