Landscape allometry: from tidal channel hydraulic geometry to benthic ecology

The use of hydraulic geometry and other geomorphic indices has been recommended for habitat restoration and creation of estuarine tidal channels. Although such an approach provides design guidance for tidal channel form, it does not provide guidance for the ecological consequences of channel form. This study investigates the potential linkage of the scaling of tidal channel form with ecological patterns and processes in estuarine tidal channels of the lower Chehalis River, Washington, U.S.A. Ebb tide surface velocity was related to channel size, as was exit time and export probability of tiny drogues, which mimic floating allochthonous detritus. Consequently, the amount of organic material in channel sediments scaled negatively with channel size as did the abundance of benthic surface deposit feeders. These observations suggest that the highest concentrations of fish feeding in estuarine tidal channels may be in smaller channels or in the smaller and more distal portions of large channels. Scaling of ecological patterns and processes with tidal channel size may be an example of a more general ecological scaling with landscape form, i.e., landscape allometry.