More than 200 marine species, including deepwater sharks, leafy sea dragons and octopuses, have been killed by a toxic algal bloom that has been affecting South Australia’s coastline since March.

Nearly half (47%) of the dead species were ray-finned fish and a quarter (26%) were sharks and rays, according to OzFish analysis of 1,400 citizen scientist reports.

Cephalopods – such as squid, cuttlefish and octopuses – accounted for 7%, while decapods – crabs, lobsters and prawns – made up 6% of species reported dead or washed up on beaches.

The OzFish South Australian project manager, Brad Martin, said the harmful bloom – of Karenia mikimotoi algae – was like a toxic blanket that smothered marine life.