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ALLOCATION OF DIGESTED MATERIALS TO MAIN BODY COMPARTMENTS OF THE SEA URCHINS Mesocentrotus nudus AND Hemicentrotus pulcherrimus  

Eri Inomata*, Ayaka Horikoshi, Hikaru Endo, Masakazu N. Aoki and Yukio Agatsuma
 
Graduate School of Agricultural Science
Tohoku University
Sendai, Miyagi 981-8555, Japan
e.inomata@bios.tohoku.ac.jp

For exploitation of the potential stock of Mesocentrotus nudus on barren habitats and Hemicentrotus pulcherrimus that is not commercially harvested in northern Japan, short-term feeding culture to enhance gonad production will be desirable. To determine the most optimum season for the culture, this study aims to clarify the seasonal and species-specific allocations of digested dry matter, carbon (C) and nitrogen (N) to major body compartments of M. nudus and H. pulcherrimus fed a formulated diet.

We conducted the four-week feeding trials four times during June-July and October-November in 2012, and January-February and April-May in 2013. We weighed four main body compartments (test, lantern, gut, gonad, dry), and analyzed C and N contents at the start and end of the feeding trials. We calculated apparent allocation rate (%) (dry matter, C or N gain of each main body compartments × 100/ dry matter, C or N digested). Digestibility of C and N (C or N digested × 100/ C or N intake) of the feed by H. pulcherrimus was significantly higher than those by M. nudus except for the trial during January-February. For M. nudus, the N apparent allocation rates to gonad were high during June-July, January-February and April-May, although the rate to test was also high during January-February. This suggests that feeding after February would be efficient to promote the gonad production in M. nudus. For H. pulcherrimus, the apparent allocation rates of dry matter, C and N to gonad were markedly high during June-July. The short-term intensive feeding during this period appears to enhance the gonad production in H. pulcherrimus.




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