Whether on land or at sea, the researchers found, the result was the same: Remove the apex consumer and the whole ecosystem suffers, as the initial loss sets off a cascade of changes all the way down the food chain. “Predators have a huge structuring influence," ecologist Stuart Sandin, one of the researchers, told LiveScience. "When you remove them you change the biology, which is typically profound and complex. And in many cases it's not necessarily predictable." While removing an ecosystem's top dog---or shark, or wolf, or elephant---is bound to have a big impact, just what that impact will be varies widely.