It shows as a rubber-like hardening of fat reserves which then become unavailable for normal metabolism, resulting in extreme pain, loss of mobility and death.

Dead and dying bottom-feeding catfish Clarias gariepinus that had ingested toxic pollutants such as heavy metals, had become an easy source of food for the crocodiles, with a resulting transfer of the toxins.

Earlier, in 2007, at the Loskop Dam, higher in the Olifants River, crocodile deaths were linked to a mass die-off of fish after sewage pollution caused cyanobacterial blooms.

High autumnal mortality among migratory herons and caused by cyanobacterial blooms, is seen regularly in brackish impoundments at Chesapeake Bay in the United States.

[9] The Massingir Dam in Mozambique, and just downstream of the Olifants Gorge, was constructed in the 1970s, but the country's civil war delayed installation of the sluice gates.