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Yurista, Peder M., 1992. Embryonic and Postembryonic Development in Bythotrephes cederstroemii. University of Michigan Reprinted from Canadian Journal of Fisheries and Aquatic Sciences (1992) 49(6): 1118-1125 Embryonic and Postembryonic Development in Bythotrephes CederstroemiiLaboratory observations were made of embryonic development time for parthenogenic Bythotrephes cederstroemii under differing temperatures spanning the range when Bythotrephes may be present in the plankton of Lake Michigan. Postembryonic development was documented for parthenogenically produced and sexually produced offspring. The complete life cycle of Bythotrephes was observed to have two distinct morphological series. Development time from birth to primaparity, consisting of three instars, was 14.0 ± 1.63 d at 12.7șC for pathenogenically produced offspring. Development time at 12.7șC for gametogenically produced offspring was 13.7 ± 1.57 d with four instars. Because parthenogenic eggs released into the brood sac of Bythotrephes do not become obvious until the embryo development is well advanced, a useful model for birth rate calculations in field work was developed based on observable morphological traits of the embryos within the brood sac. A curvilinear logarithmic model of development time (D, hours) as a function of temperature (T degrees Celsius) was fit to the embryonic development data: log (D) = 6.840 -7.305log (T) + 2.490log(T) 2. Entire Paper |
