Metabolic and embryonic responses to terrestrial incubation of Fundulus grandis embryos across a temperature gradient

Abstract

This study simulated terrestrial incubation and measured rates of embryogenesis, nitrogen elimination, heart rate, lactate production, maximum length of time a hatch could be delayed and developmental responses of terrestrially incubated Gulf killifish Fundulus grandis embryos at temperatures ranging from 20 to 30° C. Temperature had a positive relationship with rate of embryogenesis, but a negative relationship with extent of extended incubation. The 30° C treatment reached embryonic maturity 6 days before the 20° C treatment. Embryos hatched between intervals of 240 and 336, 144 and 288, 96 and 240 and 96 and 192 h after reaching developmental maturity for the 20, 23, 26 and 30° C treatments. Significantly higher concentrations of total nitrogen, in the form of ammonia and urea, were recorded in the 20 and 30° C treatments. While temperature significantly influenced lactate and ATP concentrations, no significant influence of time of incubation was detected. Terrestrial embryos displayed an ability to develop quickly during embryogenesis and prolong incubation for an extended period of time after reaching embryonic maturity. This adaptation may be a life-history trait used to minimize asynchronous hatching, cannibalism and cohort size heterogeneity.

Fish embryos on land: terrestrial embryo deposition lowers oxygen uptake without altering growth or survival in the amphibious fishKryptolebias marmoratus

“…The natural hatching time of K. marmoratus is extremely variable (between 20 and 90 days; Sakakura and Noakes, 2000) and may depend on environmental stimuli, which may partly explain why air-reared embryos did not hatch at 15 dpr, despite being hatching competent. Typically, teleost embryos must be in water to trigger hatching and therefore the ability to delay hatching is helpful when they incubate partially or completely out of water (Brown and Green, 2014;Ishimatsu and Graham, 2011;Martin, 2015;TingaudSequeira et al, 2009). The metabolic rate of air-reared embryos was significantly lower than that of embryos reared in water at the three time points measured, in contrast to our prediction.…”

Air‐breathing fishes

“…The eight research articles cover a fairly broad range of topics and species. Brown & Green () investigate how temperature influences embryogenesis during aerial incubation of eggs of the Gulf killifish Fundulis grandis (Baird & Girard 1859), a species that deposits eggs on marsh grasses at high water on spring tides. Magellan et al () and Urbina et al () provide new information about how different galaxiid species utilize adaptations for cutaneous respiration to tolerate periodic aerial exposure.…”