Pattira PongtippateeRoengsak LuppanakanePinij ThaweethamseweePornpimol KiriratWattana WeerachatyanukulBoonsirm WithyachumnarnkulPrince of Songkla UniversityCenter of Genetic Engineering and Biotechnology (Biotec)Mahidol University2018-09-242018-09-242010-01-01Aquaculture Research. Vol.41, No.2 (2010), 227-232136521091355557X2-s2.0-74349123399https://repository.li.mahidol.ac.th/handle/20.500.14594/28549The aim of this study was to determine whether magnesium (Mg2+) in seawater is required for egg activation of the black tiger shrimp Penaeus monodon and whether manipulation of Mg2+ levels can be used to delay the process and thereby synchronize egg activation. Female P. monodon broodstock were allowed to spawn in artificial seawater containing Mg2+ at varying levels with respect to the normal (100%) level: 100%, 50%, 20% and 0%. Egg activation occurred normally at 100% Mg2+, incompletely at 50% and 20% Mg2+ levels and did not occur at all with 0% Mg2+. The fertilization rate with 100% Mg2+ was observed to be 83%, but fertilization failed to take place in all the other groups. The fertilization rate was restored from 0% to 76% following the 20% Mg2+ level treatment when Mg2+ levels returned to normal (100%) as soon as spawning was completed. This study suggests that the level of Mg2+ in seawater plays a vital role in P. monodon egg activation, and that commencement of this process could be delayed by manipulation of the Mg2+ level during and immediately after spawning. © 2009 Blackwell Publishing Ltd.Mahidol UniversityAgricultural and Biological SciencesArticleSCOPUS10.1111/j.1365-2109.2009.02322.x