title: Effects of low-oxygen conditions on embryo growth in the painted turtle, Chrysemys picta.
abstract: Low-oxygen conditions (hypoxia; <21% O2) are considered unfavorable for growth; yet, embryos of many vertebrate taxa develop successfully in hypoxic subterranean environments. Although enhanced tolerance to hypoxia has been demonstrated in adult reptiles, such as in the painted turtle (Chrysemys picta), its effects on sensitive embryo life stages warrant attention. We tested the hypothesis that short-term hypoxia negatively affects growth during day 40 of development in C. picta, when O2demands are highest in embryos. A brief, but severe, hypoxic event (5% O2for 0.5 h) moderately affected embryo growth, causing a 13% reduction in mass (relative to a normoxic control). The same condition had no effect during day 27; instead, a nearly anoxic event (1% O2for 72 h) caused a 5% mass reduction. All embryos survived the egg incubation period. Our study supports the assumption that reptilian embryos are resilient to intermittently low O2in subterranean nests. Further work is needed to ascertain responses to suboptimal O2levels while undergoing dynamic changes in developmental physiology.
authors.affiliation: Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, USA.
authors.forename: Gerardo A
authors.initials: GA
authors.lastname: Cordero
authors.affiliation: Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, USA.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Karnatz
authors.affiliation: Technical University of Denmark, National Institute of Aquatic Resources, Freshwater Fisheries, Silkeborg, Denmark.|Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Porto, Portugal.
authors.forename: Jon C
authors.initials: JC
authors.lastname: Svendsen
authors.affiliation: Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, USA.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Gangloff
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001835:Body Weight; D000860:Hypoxia; D010100:Oxygen / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption; D014426:Turtles / Q000196:embryology* / Q000378:metabolism*
chemical_list: D010100:Oxygen
keywords: embryo metabolism; embryo respiration; growth rate; nest environment; oxygen consumption rate