Dolphins are near the top of the food chain which means they are at risk from accumulative pollutants.
Heavy metals are a major concern because they do not readily break down and can have a toxic effect on both the dolphins and their environment. (http://www.epa.sa.gov.au/xstd_files/Water/Report/metal_dolphins.pdf).
The EPA (Environment Protection Authority) states that “heavy metals are released into the marine environment from industries, wastewater treatment plants and stormwater runoff from roads”.
The Port River is an industrial area. It has Metropolitan Adelaide’s Power Plants, a large wastewater treatment plant, the Penrice Soda factory and plans for new industrial and residential development.