mesohabitat definition
mesohabitat is defined as the interdependent set of the ecohydraulic variables over a morphological unit. The term “microhabitat” (i.e., micro-scale habitat) is defined as the localized depth, velocity, temperature, and substrate at the hydraulic-unit scale without regard to the surrounding conditions. It is often possible to empirically relate ecological function to microhabitat variables (▇▇▇▇▇, 1986), but doing so provides a limited understanding of how and why fluvial-ecological linkages are spatially related. There is a general lack of studies that nest the micro-scale requirements of aquatic species within the meso-scale context of an assemblage of morphological units. Previous studies have provided justification why morphological units should be able to explain fluvial-ecological relations. First, they are considered to be the “fundamental building blocks of rivers systems” (▇▇▇▇▇▇▇ and ▇▇▇▇▇▇, 2000). Also at the meso-scale, the concept of morphological units has been proposed as a framework for classifying streams based on their physical characteristics that is typically linked to instream habitats (▇▇▇▇▇▇▇ et al., 1998). ▇▇▇▇▇▇ and ▇▇▇▇▇▇ (2000) stated that a morphological unit approach “represents an important linking scale between the detail of micro-scale habitat hydraulics and the need for network-scale appraisals for management of channels and flows.” Second, some studies have found that mesohabitat is a good predictor of fish utilization patterns (▇▇▇▇▇ and ▇▇▇▇▇▇, 1998; ▇▇▇▇▇▇▇▇, 2007). Finally, the type and distribution of morphological units have been found to be sensitive to land use within the watershed (▇▇▇▇▇▇▇ et al., 2003). In terms of practicality, the meso-scale provides a manageable resolution of analysis that balances scientific detail with the potential for catchment- scale application (▇▇▇▇▇▇▇ et al., 1998); the study of the form, function and distribution of morphological units is therefore useful both in terms of scaling-up to watershed scale estimates of habitat capacity and for assessing how this might be impacted by human activity (▇▇▇▇▇▇▇▇ et al., 1986; ▇▇▇▇▇▇ et al., 1989; ▇▇▇▇▇▇▇ et al., 2001).