2023 Early Hearing Detection & Intervention Conference
March 5-7, 2023 • Cincinnati, OH
5/21/2018 | 10:15 AM - 10:30 AM | CAN A SMALL BLUE-GREEN ENDOSYMBION FIX ENOUGH NITROGEN TO SUPPORT A FOUR LEVEL FOOD CHAIN? | 330 B
CAN A SMALL BLUE-GREEN ENDOSYMBION FIX ENOUGH NITROGEN TO SUPPORT A FOUR LEVEL FOOD CHAIN?
Inverse trophic pyramids are common in streams and lakes, where large densities of insects and fish are supported by low algal biomass. Upside-down pyramids are often attributed to algal traits that increase trophic efficiency (i.e., high turnover rates, minimal defenses, high caloric value). Our research expands this field beyond energy and carbon to test how nitrogen fixation affects food chain length and trophic pyramids. In the Eel River (CA), the food base comprises Cladophora glomerata and its abundant epiphytic diatoms. Diatoms in the family Rhopalodiaceae, which contain a cyanobacteria endosymbiont, often dominate the epiphyte assemblage. Here we combine small-scale measurements using 15N and Nanoscale Secondary Ion Mass Spectroscopy (nano-SIMS) with watershed scale surveys to address the following: 1) What are the rates of nitrogen fixation in the Cladophora epiphyte matrix? 2) How does N fixed by the endosymbiont move throughout the matrix to non N-fixing algae and bacteria? 3) How important is nitrogen fixation to higher trophic levels? Results indicate very high nitrogen fixation rates, demonstrating that under some conditions N fixed by the endosymbiont is an important source of nitrogen for higher trophic levels.
- Biogeochemistry
- Nitrogen
- Isotope
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Presenters/Authors
Jane Marks
(), Northern Arizona University, jane.marks@nau.edu;
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Mary Power
(), University of California, Berkeley, mepower@berkeley.edu;
Dr. Mary E. Power is Professor in the Department of Integrative Biology at the University of California, Berkeley. She was awarded an honorary doctorate by Umea University, the Kempe Medal for distinguished ecologists, and the Hutchinson Award from the American Society of Limnologists and Oceanographers. She is a member of the California Academy of Science, the American Academy of Arts and Sciences, and National Academy of Sciences, USA. She has served on the Editorial Board of PNAS (2014 to present) and Science (2006-2009). Mary also served as President of the American Society of Naturalists, and of the Ecological Society of America. Since 1988, she has been the Faculty Director of the Angelo Coast Range Reserve, (one of the UC Natural Reserve System sites, a 3500 ha reserve protected for university teaching and research). She has studied food webs in temperate and tropical rivers, as well as linkages of rivers, watersheds and near-shore environments. Focal organisms include cyanobacteria, algae, invertebrates, fish, estuarine crustaceans and terrestrial grasshoppers, spiders, lizards, birds and bats. By studying how key ecological interactions depend on landscape and temporal contexts, her group hopes to learn how river-structured ecosystems will respond to changes over space and time in climate, land use, and biota. Her group also collaborates closely with Earth and atmospheric scientists in site-based research to investigate linkages among riverine, upland, and near-shore ocean ecosystems.
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Jennifer Pett-Ridge
(), Lawrence Livermore National Lab, pettridge2@llnl.gov;
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Xavier Mayali
(), Lawrence Livermore National Lab, Mayali1@llnl.gov;
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Peter Weber
(), Lawrence Livermore National Lab, weber21@llnl.gov;
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Bruce Hungate
(), Northern Arizona University, bruce.hungate@nau.edu;
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