Floodplain Wetlands Are Nature's Hotels

Insights from DU CEO Dale Hall

From the very beginning, Ducks Unlimited has focused its science and education efforts on wetlands and grasslands, and how those habitats support our continental waterfowl populations. We have often talked about how wetlands provide a myriad of benefits to as many as 900 species, purify water, reduce storm damage, and recharge our aquifers. But we have seldom talked about the aquatic species that are included in the 900, especially fish and their use of the same floodplain wetlands so important to waterfowl.

Across the world, from pole to pole, wetlands function in the same manner and provide the same basic benefits. The types of wetlands can vary, as can their individual functional benefits, depending on how they receive water. Generally speaking, there are two types of wetlands: those that hold ponded rainfall or discharges from the groundwater table, but are not connected to adjacent permanent rivers and streams except by underground flows (and some of these are truly isolated with no connectivity); and those wetlands that are inundated by rising rivers, particularly in the spring when snowmelt is occurring and spring rains send significant amounts of drainage into constricted channels. For the latter, fish and other aquatic life have evolved to make important use of these floodplains for spawning and rearing young in a relatively quiet, slow-moving environment.

I have often referred to these floodplains as "nature's hotels" because they are crucial for waterfowl during the winter months, and then serve as essential fish habitat after the ducks leave and the spring floods occur. Species of all types in the ecosystem have evolved over the eons to take advantage of this phenomenon. We know very well how much these areas benefit ducks, especially when we're standing thigh-deep next to a bottomland hardwood oak tree in the flooded timber enjoying some of the greatest hunting on earth. But did you know that just as the ducks are "checking out of the hotel" the fish are beginning to arrive? Not only that, did you know that the entire health of the river throughout the year depends on the food produced in this highly fertile floodplain? Well they do and it does!

An article in this issue written by Drs. Mark Petrie of Ducks Unlimited and Jacob Katz of California Trout reveals how important these areas are for food productivity. When we biologists talk about the "carrying capacity" of habitat, including rivers, it is important to know that the carrying capacity (ability to support a certain number of species and individuals) is determined by the harshest conditions during the year, not the best. You see, it is this harsh period when only the minimum biological capacity exists that determines how many members of the species will survive for the renewal of life the next spring. The food (invertebrates such as aquatic insects, freshwater shrimp, crawfish, etc.) produced by the decomposing leaves and grasses supports a literal explosion of life that will serve to feed the river as the water recedes and these populations are carried or swim back into the adjacent river. Without both the floodplain connection to the river and the food it produces, the health of the river is in serious jeopardy.

That's why Ducks Unlimited works with our partners to make sure that natural wetland functions occur, even when the vegetative community might be different than what was originally there. We have learned how to use current conditions to mimic natural processes and maintain one of the most important natural hotels on earth.

Dale Hall, 
Chief Executive Officer