Effects of variable egg incubation temperatures on the embryonic development in Arctic charrSalvelinus alpinus

Abstract

An evaluation of different thermal regimes during incubation of Arctic charr Salvelinus alpinus L. egg was conducted with regard to embryo survival and development. The study consisted of two major parts: In experiment A, a range of commonly used thermal regimes, constant and variable ranging from 2.7°C to 7°C, were tested for differences in embryo survival and developmental status of newly hatched alevins. Experiment B assessed the timing of a shift from autumn (6°C) to winter temperature (2.5°C) and its effect on embryo survival and the occurrence of spinal deformities in newly hatched alevins. In general, incubations that were initiated at temperatures below 3°C resulted in significantly higher mortality rates and spinal deformity frequencies than other treatments. Hence, Arctic charr eggs require an initial warmer period for unimpaired embryonic development. A general negative correlation was found between the duration of this warmer period (6°C) and both mortality rates and frequency of spinal deformities. The total absence of the 6°C period had the most detrimental effect, with deformity frequencies at least four times higher than all treatments with an initial warmer period. The upper incubation temperature threshold was not reached in the study. The highest temperature tested (7°C) did not result in excess mortality or increased deformity frequency. Higher incubation temperature resulted in less developed alevins at hatching, i.e. alevins were smaller with more yolk remaining. However, measurements on alevins from incubations at variable temperatures revealed different temperature effects on growth and yolk consumption during different parts of embryonic development.

Impacts of chiller failure on temperature change in isolation incubators for salmonids

“…The impacts of this temperature change were relatively constant over the development stage corresponding to 68 to 160 degree-days (day °C). Even slow lowering of incubation temperature from 7° to 3°C during early development resulted in increased deformities and mortality in Arctic charr (Salvelinus alpinus) embryos (Jeuthe et al, 2015). At later stages of development, rapid temperature fluctuations between 3.5° and 6°C did not affect the number of deformities or mortalities in this species.…”

Artificial Induction and Genetic Structure Analysis of Tetraploid Turbot Scophthalmus maximus

“…Generally, before the first cleavage, the low synchronization of fertilized eggs, the complexity of cleavage regulation and environmental changes will affect the development of fertilized eggs, making it difficult to determine the optimal treatment time (Jeuthe et al, 2016). If treated in advance, the fertilized eggs will be shocked before they reach the expected level, which greatly reduces the induction efficiency.…”

Salmonid fish: model organisms to study cardiovascular morphogenesis in conjoined twins?

“…That we have observed only one pair of conjoined twins that have survived the first feeding period in our research facility during the last 35 years, and that we found 0.4 % eyed eggs with four eyes in a random population of Atlantic salmon, all hatching to become conjoined twins, supports the notion that conjoined fish twins are rare and very seldom survive the transition from yolk sac absorbtion to external feeding. Previous studies have shown the occurrence of conjoined twins at hatch to be 0.2 % in seahorses ( Hippocampus guttulatus ) [ 21 ], 0.07 % in pink salmon ( Oncorhynchus gorbuscha ) [ 22 ], 0.6 % in Arctic char [ 23 ], 0.1 % in Nile tilapia ( Oreochromis niloticus ) and blue tilapia ( Oreochromis aureus ) [ 24 ], 0.3 % in Porichthys notatus [ 25 ], and 0.05 % in coho salmon ( Oncorhynchus kisutch ) [ 26 ]. Although the above mentioned literature shows that twinning is not a typical observation in fish fry, there are reports on massive outbreaks; for instance there is a report on an epidemia where only 10.000 out of 153.000 eggs put down survived, and the number of conjoined twins was observed to run into the thousands [ 16 ].…”

“…In Atlantic salmon, 10 °C during egg incubation is high enough to induce developmental anomalies such as aplasia of septum transversum , and 8 °C is recommended as a maximum for commercial farming [ 29 ]. Earlier studies have shown that elevated temperature may [ 17 ], or may not [ 23 ] increase the occurrence of conjoined twins in salmonids. Further, heat shock treatment for 3–4 min applied 27 min after fertilization increased the twinning rate by three or four times over that of un-shocked eggs in Nile and blue tilapia [ 24 ].…”