Effect of photoperiod on the productivity factors of the tropical estuarine calanoid copepod, Acartia tropica

Wilson, Jess Maria and Ignatius, Boby and Santhosh, B and Sawant, Paramita Banerjee and Rajesh, N and Anju Soma, S (2025) Effect of photoperiod on the productivity factors of the tropical estuarine calanoid copepod, Acartia tropica. Journal of the Marine Biological Association of India, 67 (2). pp. 22-28. ISSN 2321-7898

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Abstract

The present study evaluated the effect of photoperiod on the productivity factors of the tropical calanoid copepod Acartia tropica. Population growth and composition, intrinsic rate of population increase, individual egg production and egg hatching success (EHS) of Acartia tropica were assessed at four different photoperiod regimes [Light (L): Dark (D) hours], viz. 0L: 24D, 8L: 16D, 16L:8D, 24L: 0D. After eight days of culture, the highest mean population count and intrinsic rate of population increase were recorded at 8L:16D photoperiod regime, which was not significantly different (p>0.05) from the copepods maintained at 0L:24D photoperiod regime. The result of the population composition study indicates the highest number of adults and naupliar stages in the 8L:16D photoperiod condition. Similarly, the highest mean individual egg production and egg hatching success were also recorded in the 8L:16D photoperiod condition, which was statistically significant (p˂0.05) compared to others. Percentage nauplii survival does not show any significant difference (p>0.05) between 0L: 24D, 8L: 16D, 16L:8D photoperiod regimes. However, 24L: 0D photoperiod regimes recorded the lowest percentage of nauplii survival, which was significantly (p˂0.05) lower than other treatments. Similarly, different photoperiod regimes did not affect the sex ratio of adult A. tropica in the present study. The results of the present study indicate that among the various photoperiod conditions evaluated, 8L: 16D is the optimum photoperiod condition for the culture of A. tropica, and that photoperiod has a significant influence on its productivity factors.

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