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| Growth of Sea Cucumber and Water Quality Features in Polyculture of Sea Cucumber with Seaweeds Sargassum thunbergii and Gracilaria lichenoides |
| WANG Jun,TIAN Xingli,JIANG Wenlian |
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Abstract Juvenile sea cucumber A postichopus japonicus with body weight of (5 .07 ± 0 .45) g was stocked at a rate of 11 ind/m2 and polycultured in a bamboo made 4 m(width) × 4 m(length) × 1 .5 m(height) grid tied by PVA strings of sea weeds Sargassum thunbergii with body length of (31 .7 ± 10) cm [body weight of (2 .32 ± 1 .2) g] at a rate of 187 .5 g/m2 (A1 ) ,375 g/m2 (B1 ) ,562 .5 g/m2 (C1 )and 750 g/m2 (D1 )for 45 days and Gracilaria lichenoides with the same size at a rate of 250 g/m2 (A2 ) ,500 g/m2 (B2 ) ,750 g/m2 (C2 )and 1000 g/m2 (D2 ) for 60 days in a pond .The polyculture was conducted alternatively ,that is ,G . lichenoides was stocked later into the grids (A2 ,B2 ,C2 andD2 ) which S .thunbergii was tied initially (A1 , B1 ,C1 and D1 ) .The growth of the sea cucumber and sea weeds and levels of chlorophyll a ,total nitrogen (TN) ,total phosphorus (TP) and total organic carbon (TOC) were determined in a 15 day interval .The results showed that there was higher specific growth rate (SGR)in the sea cucumber polycultured with the seaweeds than in the sea cucumber in monoculture , significantly higher in polyculture C than in the monoculture(P < 0 .05) .The chlorophyll a level was shown to be declined in the polyculture water with increase in net yield of the sea weeds .There were significantly lower levels of TN ,TP and TOC in the sediments in the polyculture than those in the monoculture of sea cucumber(P < 0 .05) .
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Received: 25 September 2015
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