Ulva australis as a tool for monitoring metal-polluted estuarine system; spatial and temporal considerations

This study investigated temporal and spatial patterns of heavy metal content in Ulva australis. Samples were collected from the Derwent Estuary, Tasmania, Australia, over 3 years (2013-2015) at locations where historically arsenic, cadmium, lead and zinc were high in sediments and seawater. Zinc and lead content were high in U. australis at all sampling times, with levels consistent with the spatial distribution of metal within the system. Zinc in Ulva varied seasonally (4.8 – 320.7 mg·kg-1), but lead did not. Zinc and lead were highest in the middle-upper estuary, close to the zinc smelter, where seawater concentrations were higher. The results suggest that spatial variation of metal content in Ulva is a reflection of variability in the seawater, which in turn indicates that U. australis could be used for monitoring the effects of metals in estuarine systems, and that U. australis could be a useful addition to existing management strategies.