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Abstract
The endogenous cardiac activity rhythm of the Norway lobster Nephrops norvegicus was studied under constant conditions of darkness by means of a computer-aided monitoring system (CAPMON). Time series recordings of the heart rate (beats min−1) were obtained from 47 adult males freshly collected from the continental slope (400–430 m) in the western Mediterranean. Periodogram analysis revealed the occurrence of circadian periodicity (of around 24 h) in most cases. A large percentage of animals showed significant ultradian periods (of around 12 and 18 h). The analysis of the circadian time series revealed the occurrence of peaks of heart rate activity during the expected night phase of the cycle. These results are discussed in relation to the emergence and locomotor activity rhythms of the species.
Acknowledgements
Special thanks are due to Dr. F. Sardà, Chief Researcher of the project for his support and valuable comments, to Dr. J.B. Company, Prof. E. Naylor, Dr. I.J. McGaw, Dr. A. Díez-Noguera and Dr. T. Cambras for important suggestions and comments during the paper preparation. J.A. Garcia provided important technical support. The authors wish to thank the master and crew of the fishing vessel “Maireta III” for sampling assistance. CICYT Project MAR98-0935 supported this research.
