Print PageDue to the Mediterranean climate of California, the Sacramento River has an abundance of small tributaries that contain water only during the winter/spring wet season. Over the past years we examined the ecology of these tributaries in terms of native fishes and aquatic macroinvertebrates and highlight the critical role this underappreciated habitat plays in the overall functioning of the entire riverine ecosystem. In this talk I discuss and summarize data from five individual studies examining ecological aspects of this habitat.
Results/Conclusions
In a study of juvenile Chinook growth in seasonal tributaries using otolith microstructure we find that fish grow bigger and faster on the abundant food and warmer temperatures in seasonal tributaries. In a four-year study on the spatial distribution and abundance of native fish larvae in tributaries of the upper Sacramento River we find that certain critical tributaries (Mud Creek) produce almost an order of magnitude more native fish larvae than near by permanent streams. In a study comparing the distribution and abundance of aquatic macroinvertebrates in a seasonal tributary with a nearby permanent stream we find the seasonal tributary contains unique taxa as well as higher drift densities and an ecologically distinct community. In a cross-watershed comparison of larval fish drift density we find that a seasonal tributary (Mud Creek) produces more larvae on a per volume basis than all other streams/rivers we examined. In a comparison of juvenile Chinook growth morphology between seasonal and permanent streams using geometric morphometrics we find that salmon show distinct phenotypic plasticity and their growth is characteristically different in seasonal tributaries, possibly leading to a better and healthier fish morphology. Taken together, this body of work highlights the critical importance of this habitat and strongly suggests the need for watershed-level conservation.
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