Noninvasive Determination of Embryonic Heart Rate during Hatching in the Brown Noddy (Anous stolidus)
1991; Oxford University Press; Volume: 108; Issue: 3 Linguagem: Inglês
10.2307/4088100
ISSN1938-4254
Autores Tópico(s)Aquaculture Nutrition and Growth
ResumoWe used an audiocartridge system, which measures the ballistic movements of the egg attributable to embryonic cardiac contractions, to determine the heart rate (HR) of the Brown Noddy (Anous stolidus) before and during the prolonged hatching process. The average heart rate at 36°C in 8 embryos (mean fresh egg weight = 38 g) was 262 beats/min (bpm) on the last day of prepipping, and 264 bpm on the first day of shell fracture (external pipping). Heart rate increased to 291 bpm after penetration of the air cell by the beak (internal pipping), and increased to 310 bpm on the last day of incubation. With a few exceptions, the heart rate, which did not change systematically during the last stage of prepipping, remained unchanged early in external pipping and then increased markedly with the initiation of pulmonary respiration. Changes in heart rate during hatch may be related to increases in the oxygen consumption of the embryo. The heart rate was highly variable even at constant ambient temperatures. It changed according to a temperature coefficient $({\rm Q}_{10})$ of 2 at all developmental stages, when the ambient temperature was modified 2°C from the control (36°C).
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