Research Article

Multiple trophic pathways support fish on floodplains of California's Central Valley

Published: 2023-1

Journal: Journal of Fish Biology

DOI: 10.1111/jfb.15248

Abstract

We used compound‐specific isotope analysis of carbon isotopes in amino acids (AAs) to determine the biosynthetic source of AAs in fish from major tributaries to California's Sacramento‐San Joaquin river delta (i.e., the Sacramento, Cosumnes and Mokelumne rivers). Using samples collected in winter and spring between 2016 and 2019, we confirmed that algae are a critical component of floodplain food webs in California's Central Valley. Results from bulk stable isotope analysis of carbon and nitrogen in producers and consumers were adequate to characterize a general trophic structure and identify potential upstream and downstream migration into our study site by American shadAlosa sapidissimaand rainbow troutOncorhynchus mykiss, respectively. However, owing to overlap and variability in source isotope compositions, our bulk data were unsuitable for conventional bulk isotope mixing models. Our results from compound‐specific carbon isotope analysis of AAs clearly indicate that algae are important sources of organic matter to fish of conservation concern, such as Chinook salmonOncorhynchus tshawytschain California's Central Valley. However, algae were not the exclusive source of energy to metazoan food webs. We also revealed that other sources of AAs, such as bacteria, fungi and higher plants, contributed to fish as well. While consistent with the well‐supported notion that algae are critical to aquatic food webs, our results highlight the possibility that detrital subsidies might intermittently support metazoan food webs.

Faculty Members

  • Joshua H. Viers - UC Merced Merced California USA
  • Bobby J. Nakamoto - EDGE Institute UC Riverside Riverside California USA
  • Marilyn L. Fogel - EDGE Institute UC Riverside Riverside California USA
  • Mollie Ogaz - Center for Watershed Sciences UC Davis Davis California USA
  • Christina J. Bradley - Salisbury University Salisbury Maryland USA
  • Nicholas J. Corline - Center for Watershed Sciences UC Davis Davis California USA
  • Carson A. Jeffres - Center for Watershed Sciences UC Davis Davis California USA

Themes

  • Ecosystem interactions
  • Aquatic ecology
  • Food web dynamics
  • Sources of organic matter
  • Conservation biology

Categories

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