The mysterious death of 350 elephants in the Okavango delta between May and June baffled conservationists, with leading theories suggesting they were killed by a rodent virus known as EMC or toxins from algal blooms. The Government of Botswana has now said that toxins in water produced by cyanobacteria are to blame. The Guardian reports that toxins were initially ruled out because no other species died – except for one horse – but scientists now think elephants could be particularly susceptible to cyanobacteris because they spend a lot of time bathing and drinking large quantities of water. Dr Niall McCann, the director of conservation at UK-based charity National Park Rescue, who initially suggested the elephants may have been poisoned or died from an unknown pathogen, has questioned the government’s announcement though, saying that “without good samples from dead elephants, all hypotheses are just that: hypotheses”.