Deadly combination caused mass marine deaths, not desal plant, says official report This dead young dolphin washed ashore on Seacliff beach in April. Picture: Newsforce Source: adelaidenow A DEADLY combination of high water temperatures, algal blooms and a virus caused the mass fish and dolphin deaths over the past three months, according to an official report that clears the desalination plant of any blame A tiny, spiny diatom was among the culprits for the fish kills, lodging barbs in fish gills leading to inflammation and death. A multi-agency investigation which included pathology tests found some weaker fish became susceptible to lethal bacterial infection due to high water temperature and harmful algae. It also concluded that dolphin Morbillivirus was the underlying cause of the death of the 34 mostly young dolphins discovered since March 1, causing an immune suppression which allowed fungal and parasite infections to thrive. Some of the dead fish washed ashore at Moana. Picture: Andy Sintome Minister for Agriculture, Food and Fisheries Gail Gago said no single water quality or pollution point source was found responsible for the geographically extensive series of events. "The Environment Protection Authority categorically ruled out any link to the desalination plant following an extensive review of monitoring data," Ms Gago said. During the first part of March, higher water temperatures were detected across both Spencer and St Vincent gulfs and much of the ocean waters, as far west as Fowlers Bay and reaching east to Bass Strait. Thousands of dead fish washed up along the foreshore at Moana Beach. A strong upwelling event of deeper, colder waters in early March helped start the growth of a range of micro-algae including blue green algae and a spiny diatom Chaetoceros coarctatus which has been known to be harmful to fish species. Ongoing warm weather supported the growth of micro-algae. Weather conditions changed around 20 March with strong winds blowing surface waters to the east and impacting along the metropolitan coast of Adelaide. Water samples collected along the Adelaide metropolitan coastline during the fish deaths event confirmed the presence of this spiny diatom. The barbs lodged in the gills of fish leading to inflammation and eventual death. Thousands of dead fish along the foreshore at Moana Beach. The majority of fish affected were small-bodied, bottom-dwelling species, with leatherjackets the most numerous reported. Dolphin morbillivirus is one of a group of viruses which includes the viruses that cause measles in humans, distemper in dogs and rinderpest in ruminants. Read the full report Dead fish on Seaford beach .