Zooplankton ecology and trophic resources for rearing native fish on an agricultural floodplain in the Yolo Bypass California, USA
- 321 Downloads
Out-migrating juvenile Chinook Salmon Oncorhynchus tshawytscha in California’s Central Valley lack frequent access to historical off-channel habitats such as floodplains. However, many regions have agricultural floodplains that may provide habitat value to young salmon. To determine the suitability of agricultural floodplain, this study tested whether winter-inundated rice fields in a historic flood basin in California’s Central Valley could provide adequate food resources for rearing juvenile Chinook Salmon. We examined the suitability of flooded rice fields for three post-harvest habitat types: stubble, fallow, and disced. Soil emergent and pelagic zooplankton communities were compared to determine colonization sources. Winter-inundated rice fields had high densities of zooplankton, which increased over the course of the study. Daphnia pulex, a large-bodied cladoceran and an excellent forage species of juvenile Chinook Salmon, was abundant in our study. Cladocerans colonized via source water while ostracods likely colonized from a soil egg bank. Overall, there was no discernable effect of habitat type on zooplankton community structure or density, except for D. pulex. Our results suggest that flooded agricultural rearing habitat can support juvenile Chinook Salmon based on high densities of zooplankton and other suitable habitat conditions have the potential to support a robust aquatic food web.
KeywordsFloodplain Zooplankton Daphnia Chinook Salmon Colonization Rice field
We would like to thank Sharon Lawler and Peter Moyle for comments and insights that have greatly improved this paper. Support for this project was provided by the Center for Watershed Sciences University of California Davis, Cal Marsh and Farm, California Department of Water Resources and U.S. Bureau of Reclamation as part of the Interagency Ecological Program. We thank EcoAnalysts, Inc (Moscow, ID, USA) for assistance with invertebrate sorting and identification and the Dahlgren Water Quality Lab at UC Davis for water quality analysis. Additionally, we thank Miranda Tilcock, Angelica Munguia, Emma Cox, and Nicole Aha for tireless field and laboratory work.
Funding for this project was provided by California Trout.
- Hanak E, Lund J, Dinar A et al (2011) Managing California’s water: From conflict to reconcilation. Public Policy Institute of California, San FranciscoGoogle Scholar
- Healy MC (1991) Life history of Chinook salmon. In: Groot C, Margolis L (eds) Pacific salmon life histories. UBC Press, Vancouver, pp 311–394Google Scholar
- Junk WJ, Bayley PB, Sparks RE (1989) The flood pulse concept in river-floodplain systems. Proc Int Large River Symp Can Spec Publ Fish Aquat Sci 106:110–127Google Scholar
- Katz JVE, Jeffres C, Conrad L, Sommer TR, Martinez J, Brumbaugh S, Corline N, Moyle PB (In Review) Floodplain farm fields provide novel rearing habitat for Chinook salmon: reconciling fish and farms in California. PLoS ONEGoogle Scholar
- Merritt RW, Cummins K, Berg M (eds) (2008) An introduction to the Aquatic insects of North America, 4th edn. Kendall/Hunt Publishing Company, DubuqueGoogle Scholar
- Sommer TR, Baxter RD, Feyrer F (2007) Splittail “Delisting”: a review of recent population trends and restoration activities. Am Fish Soc Symp 53:25–38Google Scholar
- Thorp J, Covich A (eds) (2009) Ecology and classification of North American freshwater invertebrates, 3rd edn. Academic Press, BostonGoogle Scholar