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Vol. 51 No. 7, 2012
Hemolymph Ecdysteroid Titers in a Brachyuran Crab Uca triangularis that Concomitantly Undergoes Molting and Reproduction
Sudha Kappalli1, Nagathinkal T. Supriya1, Velayudhan Krishnakumar1, Anilkumar Gopinathan2,*, and Ernest S. Chang3
1Post Graduate Department of Zoology and Research Centre, Sree Narayana College, Kannur 670007, Kerala, India
2School of Biosciences and Technology, VIT University, Vellore 632014, TN, India
3Bodega Marine Laboratory, University of California-Davis, Bodega Bay, CA 94923, USA
Sudha Kappalli, Nagathil T. Supriya, Velayudhan Krishnakumar, Anilkumar Gopinathan, and Ernest S. Chang (2012) Investigations
conducted thus far suggest that premolt growth and ovarian growth are
antagonistic events in brachyuran crabs, arguably implying that yolk
deposition does not occur during premolt when the ecdysteroid titer is
very high. The present paper examines ecdysteroid levels in a
brachyuran crab Uca triangularis
that exhibits simultaneous programming of premolt growth and
reproduction during certain seasons of the year. The species
exhibits 2 patterns of breeding cycles, 1 (premolt breeding cycle)
synchronous with the premolt cycle during Feb.-May, and the other
(intermolt breeding cycle) taking place only during intermolt
(Aug.-Jan.); no breeding activity occurs during June-July.
Results depicted in the present paper are also expected to help us
evaluate the possible role of ecdysteroids in reproduction in
crustaceans, a matter of active discussion during the past few
years. Yolk deposition in the intermolt breeding cycle occurs
under a very low ecdysteroid titer (3-6 ng/ml hemolymph), but it takes
place at a perceptibly higher ecdysteroid titer (12-36 ng/ml hemolymph)
in the premolt breeding cycle; a positive correlation exists between
the ecdysteroid titer and oocyte diameter during the premolt breeding
cycle. These results on the 1 hand indicate that yolk deposition
can occur at a high ecdysteroid titer (premolt titer) in a natural
population of U. triangularis;
on the other hand, it reveals that a high ecdysteroid titer (as high as
the premolt titer) is not mandatory for successful ovarian growth in
the species. The study also suggests that molting and
reproduction in the species are not mutually dependent events, as
normal yolk deposition can occur irrespective of the molt stage.
Key words: Decapod, Breeding, Growth, Hormone, Radioimmunoassay.
*Correspondence: Tel: 91-9952187178; 91-416-2202575. E-mail:ganilkumar@vit.ac.in
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