Tidal periodicity of molting in giant mud crab, Scylla serrata (forskål, 1775)
1 Camarines Norte State College – Institute of Fisheries and Marine Sciences, Mercedes, Camarines Norte, Philippines.
2 Bicol University Graduate School, Legazpi City, Philippines.
3 Coastal Resources Management Unit, Bicol University Tabaco Campus, Tayhi, Tabaco City, Philippines.
Research Article
World Journal of Advanced Research and Reviews, 2022, 16(01), 122–132
Article DOI: 10.30574/wjarr.2022.16.1.0994
Publication history:
Received on 29 August 2022; revised on 03 October 2022; accepted on 06 October 2022
Abstract:
Molting is the most crucial phase in the life cycle of mangrove crabs, leading to mortality in various culture systems. As a result of this exigency, this study was conducted to offer a cue in molting using the tidal cycle as one of the visible events in a natural context. Monitoring was carried out at every 1-hour interval (24 hours) day and night for 57 days to check for molting while taking into account key environmental elements such as tidal cycles, water current speed, and flow rate. The results showed that 70.6% of molting happened during high tide, with 93.8% of it occurring at night and 6.3% during the day. By contrast, only 29.4% occurred during low tide, showing a significant difference (T-test = 0.011, p < 0.05) between mean molts. Hence, the highest molting rate (88.2%) was observed between tidal episodes between the neap and middle cycles, with the middle tide (55.9%) occurring at 12.4±0.9 m/s, neap tide (32.4%) occurring at 16.8±2.0 m/s, and spring tide (11.8%) occurring at 9.5±1.2 m/s. Molting occurs at high tide because crabs' rheotactic behavioral responses to incoming new water help the crab's body fill with air and water throughout the molting process. Mangrove crabs employ their tidal periodicity of molting as a defense strategy against potential predators and mortality, and it can be used as a molting indicator in many culture systems.
Keywords:
Tidal cycles; Water current; Molting schedule; Indicators; Mangrove crab
Full text article in PDF:
Copyright information:
Copyright © 2022 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0