Metabolic rate and hypoxia tolerance in Girardinichthys multiradiatus (Pisces: Goodeidae), an endemic fish at high altitude in tropical Mexico

Publication date: Available online 14 September 2019Source: Comparative Biochemistry and Physiology Part A: Molecular & Integrative PhysiologyAuthor(s): Monica Vanessa Garduño Paz, José Fernando Méndez Sánchez, Warren Burggren, José Luis Antonio García MartínezAbstractThe darkedged splitfin (Amarillo fish), Girardinichthys multiradiatus is a vulnerable endemic fish species inhabiting central Mexico's high altitude Upper Lerma Basin, where aquatic hypoxia is exacerbated by low barometric pressures (lower PO2s), large aquatic oxygen changes, poor aquatic systems management and urban, agricultural and industrial pollution. The respiratory physiology of G. multiradiatus under such challenging conditions is unknown - therefore the main goal of the present study was to determine metabolic rates and hypoxia tolerance to elucidate possible physiological adaptations allowing this fish to survive high altitude and increasingly eutrophic conditions. Fish came from two artificial reservoirs – San Elías and Ex Hacienda - considered refuges for this species. Both reservoirs showed high dial PO2 variation, with hypoxic conditions before midday and after 20:00 h, ~4 h of normoxia (15 kPa) from 16:00–20:00, and ~4 h of hyperoxia (16–33 kPa) from 12:00–16:00. Standard metabolic rate at 20 ± 0.5 °C of larvae from Ex Hacienda was significantly higher than those from San Elías, but these differences disappeared in juveniles and adults. Metabolic rate at 20 ±â...
Source: Comparative Biochemistry and Physiology Part A: Molecular and Integrative Physiology - Category: Biochemistry Source Type: research