A study of four mangrove species in Australia's Moreton Bay found the trees keep toxic metals like lead and arsenic locked in the mud instead of moving them into leaves. Researchers measured metal levels in surface sediments and foliage, and calculated bioconcentration factors below one for all species and all eleven elements analysed. That means the mangroves are acting as phytostabilisers, holding contaminants in the sediment rather than letting them enter the food web. The study, published in Plant and Soil, also found species identity mattered more than sediment chemistry. Grey mangroves took up more arsenic into leaves, while other species excluded it more strongly. For coastal monitoring, the authors say sediment chemistry is a more reliable indicator than leaf tissue in these low-contamination, sulphidic environments. The results add a pollution control angle to the case for protecting mangrove ecosystems.
