Do floods wipe out animals in the soil?
During
unusually severe floods, soils become anaerobic (oxygen-free) and decay creates toxic chemicals. Up to 75 per cent of larger soil invertebrates may die or fly away, but survival varies according to species. Many earthworms and the larvae of beetles, bugs and flies move to the surface, where vast numbers get eaten by birds. On the other hand, some species of earthworm stay in the flooded soil, coping due to their high haemoglobin content. Some bugs and beetles survive as dormant eggs or can absorb oxygen from the water through their skin. A few invertebrates are also protected inside their watertight homes – the queen yellow-loosestrife bee makes waterproof burrows for her larvae, lining the walls with oil. Alex Morss