Effect of temperature on early development of white and lake sturgeon, Acipenser transmontanus and A. fulvescens

Abstract

SynopsisThe effect of constant incubation temperatures (between lo" C and 26" C) on the developmental rates was found to fit a similar exponential relationship in both the lake and white sturgeon embryos and larvae. Although the lake sturgeon had an overall slower rate of development than the white sturgeon, no statistically significant difference was detected in the slopes of the exponential equations describing the effect of temperature on developmental rate. The effect of these incub'ation temperatures on embryonic survival also did not differ between these two species. Both species exhibited optimal survival between 14-17" C and incipient mortalities occurred at 20" C. Temperatures above 20" C were lethal for white sturgeon embryos. No effect of low incubation temperature on survival was evident from this study. A comparison of these North American species with Eurasian acipenserids suggests that all the Isturgeon that have been examined exhibit a similar influence of incubation temperature on developmental rate.

Exceptional preservation of embryos in the actinopterygian Saurichthys from the Middle Triassic of Monte San Giorgio, Switzerland

“…these structures cannot represent remains of the notochord, because their section is too thick, or of the digestive tract, because they are segmented and seem to be too long if compared to the size of the skull. the size and length of these structures with respect to the associated skulls are compatible with the axial musculature (ballard & Needham 1980;Wang et al 1985) and recall the morphology of embryos in extant fishes (Figs. 5b, c).…”

“…However, it is not plausible that these rod-like structure may represent fossilized vertebrae of the embryos because they are solid cylinders while in Saurichthys vertebrae are c shaped empty rings, and also these structures are too large for this developmental stage to represent the notochord (ballard & Needham 1980;Wang et al 1985). the application of drops of a solution of nitric acid and ammonium molibdate on these structures turned their colour from white to bright yellow, indicating the precipitation of ammonium phosphomolibdate thus revealing their phosphatic nature (Green Owen 2001).…”

Etude bibliographique des principales caractéristiques de l'écologie des larves d'Acipenseridés

“…La température optimale d'incubation, en termes de survie, est comprise entre 10 et 18 °C (WANG et al, 1985). L'étendue de cette gamme est expliquée par les différences de latitudes sous lesquelles vivent les acipenseridés.…”

“…La relation entre la température et la vitesse de développement a été particulièrement étudiée par DETTLAFF et al (1993) chez les espèces soviétiques et par WANG et al (1985) chez Acipenser transmontanus et Acipenser fulvescens. Ces auteurs ont mis en évidence une relation exponentielle entre la température et la durée du développement embryonnaire.…”

“…Ainsi à 14 °C, l'éclosion des oeufs surviendra environ 200 heures après la fécondation chez Acipenser transmontanus contre 245 heures chez Acipenser fulvescens (WANG et al, 1985).…”