As Hurricane Matthew moves off the east coast of the United States leaving flood waters behind, communities are reeling. Did you ever wonder what happens to worms when it floods?
We know that when it rains, earthworms come to the surface to help regulate their breathing for migration overland. As worms don’t have lungs, they breathe through their skin, and in order to do so they need moisture. The temporary wet conditions after rain allows them to move greater distances across the soil.
Because they don’t have lungs, earthworms can’t drown like people do, either. So it’s good that earthworms can survive underwater for several days. But do earthworms ever come up in standing or running water, and if so, what do they do?
Earthworms and other invertabrates negotiate the rising and falling water tables around nutrient-rich wet areas of grassland. Spring rains and freeze and thaw cycles make the soil wetter and drier throughout the year. For the most part, earthworms and larvae migrate to higher ground when water makes the soil heavy and pushes available oxygen out.
With shorter flood events, when things dry up the worms migrate back down and recolonize. This can take two to three weeks from when flood waters recede. If flood waters are around longer, soils will take longer to dry out, but the food sources for the worms and larvae will have been removed. It can take six months or more to restore nutrients in the soil, and as long for the levels of worms and larvae to return.
Some areas, like farmland, need earthworms to help accelerate that process. Farmers and conservationists will speed the process of aerating, breaking down vegetable material, and restoring the soil by introducing earthworms to their fields and plots after flood weather– that’s what earthworms do! Establishing plant and invertebrate communities in turn supports the bird and mammal communities that rely on them. Recovery from natural disaster starts from the ground up, and having worms around can help.