http://astrobiology.asu.edu/Astrobiology/Stoichiometry/Stoichiometry.html Leadership team: J. Elser (lead), A. Anbar, S. Neuer<br/><br/>This research theme includes several tasks aimed at elucidating relationships between the availability of bioessential elements and prokaryotic ecosystems. These tasks involved: quantitative laboratory growth experiments, centered on model prokaryotes grown in nutrient-limited chemostats field studies and associated laboratory analyses at Yellowstone National Park and Cuatro Ciénegas, Mexico, evolutionary studies in the geologic and genomic records and a modeling project to understand the interconnections between the biogeochemical cycles of carbon, oxygen and bioessential nutrient elements in prokaryote-dominated oceans.<br/><br/>Summary of tasks under this research theme: <br/><br/>Task 1: Laboratory studies with astrobiology-relevant biota to determine how element <br/> limitations affect &quot;Extended Redfield Ratios&quot; (ERRs) and the physiological <br/> processing of elements in microbes<br/> Investigators: Elser (lead), Anbar, Jones, Neuer, Wolfe-Simon, and Shock<br/><br/>Task 2: Field studies at Yellowstone National Park's hot springs and in the Cuatro <br/> Ciénegas Basin, Mexico, to discover how element limitations affect the in situ <br/> ERRs and the biogeochemical processing of elements<br/> Investigators: (Yellowstone) Shock (lead), Anbar, Meyer-Dombard, Johnston, <br/> Hartnett, Hervig, Raymond<br/> Investigators: (Cuatro Ciénegas) Elser (lead), Anbar, Souza, Breitbart, <br/> Johnston, Hervig, Hollander, Sharp and Siefert<br/><br/>Task 3: Geologic and molecular evolution studies aimed at evaluating the role of <br/> multielement coupling during early Earth history<br/> Investigators: Anbar, Brocks, DuPont, Love, Lyons, Siefert<br/><br/>Task 4: Studies of biogeochemical impacts on planetary atmospheres, examining the <br/> effects of nutrient limitation on carbon export<br/> Investigators: Neuer (lead), Anbar, Gregg<br/> iWeb 3.0.4