>Enhance Aquatic Habitat Connectivity

Enhance Aquatic Habitat Connectivity

Protect and enhance aquatic habitat connectivity.
Selected for Feather River Report

Aquatic connectivity is affected by natural and artificial features (usually hard and fixed) within and along the stream channel and conditions occurring in the stream. For example, culverts, dams, sewer lines and concrete walls can totally, partially or temporarily (usually seasonally) block fish passage via physical obstruction or by creating hydraulic or hydrologic conditions that impede fish movement. Aquatic connectivity is a critical component for the long-term viability of fish and other aquatic organisms. Research has shown that many fish species (and all salmonid species) move considerable distances both up- and downstream through watersheds in order to find habitats necessary for completion of their life histories and survival. Increases in connectivity have been shown to positively affect species richness and piscivore richness (Bouvier et al. 2009). The Sacramento River and tributary streams throughout the basin provide critical spawning and rearing habitat for salmon, trout and other resident fish species. As a result of increasing water demands, dams and bank revetment for flood control, road construction, and land development, fish habitat in many subbasin watersheds has been impacted or even eliminated. The influence of water flows on aquatic habitat connectivity and the species that use these habitats (i.e., channel margins and wetlands) is well established in the scientific literature (e.g., McCullough 1999; Oliver and Fidler 2001; and Richter and Kolmes).
Connectivity is typically defined as a dynamic natural pathway that provides for the movement of energy and/or materials from one habitat type to another and/or creates a physical linkage between habitats through a natural conduit (UMRCC 2009). Materials may be abiotic (such as water, sediment and nutrients) and/or biotic (such as organisms, species or groups of species). Aquatic connectivity can be subdivided into at least these different categories:

  1. habitat connectivity;
  2. the longitudinal connection between river reaches either upstream or downstream;
  3. mainstem to tributary connectivity;
  4. lateral non-flood connectivity;
  5. lateral flood pulse connectivity; and
  6. sub-surface connectivity.

Within the scope of objective 3.3, we focus on the first four aspects of aquatic connectivity. The fifth aspect is covered by the objective pertaining to flood processes and the sixth is beyond what is feasible to develop and monitor given the resources available for this work.