title: Air exposure behavior of the semiterrestrial crab Neohelice granulata allows tolerance to severe hypoxia but not prevent oxidative damage due to hypoxia-reoxygenation cycle.
abstract: The air exposure behavior of the semi-terrestrial crab Neohelice granulata during severe hypoxia was studied. This study also verified whether this behavior mitigates possible oxidative damage, namely lipoperoxidation, caused by hypoxia and reoxygenation cycles. The lethal time for 50% of the crabs subjected to severe hypoxia (0.5 mgO2 · L(-1)) with free access to air was compared to that of crabs subjected to severe hypoxia without access to air. Crabs were placed in aquaria divided into three zones: water (when the animal was fully submersed), land (when the animal was completely emerged) and intermediate (when the animal was in contact with both environments) zones. Then the crabs were held in this condition for 270 min, and the time spent in each zone was recorded. Lipid peroxidation (LPO) damage to the walking leg muscles was determined for the following four experimental conditions: a--normoxic water with free access to air; b--hypoxic water without access to air; c--hypoxic water followed by normoxic water without air access; and d--hypoxic water with free access to air. When exposed to hypoxic water, N. granulata spent significantly more time on land, 135.3 ± 17.7 min, whereas control animals (exposed to normoxic water) spent more time submerged, 187.4 ± 20.2 min. By this behavior, N. granulata was able to maintain a 100% survival rate when exposed to severe hypoxia. However, N. granulata must still return to water after periods of air exposure (~ 14 min), causing a sequence of hypoxia/reoxygenation events. Despite increasing the survival rate, hypoxia with air access does not decrease the lipid peroxidation damage caused by the hypoxia and reoxygenation cycle experienced by these crabs.
authors.affiliation: Programa de Pós-Graduação em Ciências Fisiológicas, Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, FURG, Av. Itália, Km 8, Rio Grande, RS 96201-300, Brazil.
authors.forename: Tábata Martins
authors.initials: TM
authors.lastname: de Lima
authors.affiliation: Programa de Pós-Graduação em Ciências Fisiológicas, Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, FURG, Av. Itália, Km 8, Rio Grande, RS 96201-300, Brazil.
authors.forename: Márcio Alberto
authors.initials: MA
authors.lastname: Geihs
authors.affiliation: Programa de Pós-Graduação em Ciências Fisiológicas, Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, FURG, Av. Itália, Km 8, Rio Grande, RS 96201-300, Brazil.
authors.forename: Luiz Eduardo Maia
authors.initials: LE
authors.lastname: Nery
authors.affiliation: Programa de Pós-Graduação em Ciências Fisiológicas, Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, FURG, Av. Itália, Km 8, Rio Grande, RS 96201-300, Brazil. Electronic address: maciel-fe@hotmail.com.
authors.forename: Fábio Everton
authors.initials: FE
authors.lastname: Maciel
mesh_terms: D000388:Air; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D003386:Brachyura / Q000502:physiology*; D005121:Extremities / Q000502:physiology; D015227:Lipid Peroxidation; D008297:Male; D009132:Muscles / Q000502:physiology; D010100:Oxygen / Q000502:physiology*; D012720:Severity of Illness Index; D016019:Survival Analysis; D013997:Time Factors; D014867:Water
chemical_list: D014867:Water; D010100:Oxygen
keywords: Aerial exposition; Behavior; Crab; Decapoda; Hypoxia; Lipid peroxidation; Reoxygenation