• Proceedings of the Korea Society of Environmental Biology Conference
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• 2003.11a
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• pp.92-97
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• 2003

Community structure of macrobenthos was studied on Angol clam farming ground of Chinhae Bay in the southern coast of Korea. Macrobenthos samples were collected monthly using a quadrate at each station from March 1998. Macrobenthos samples were seived by 1.0mm mesh seive. Mean grain size was 0.267 mm. A total of 111 macrobenthos species were sampled with a mean density of 1,651ind/m$^2$and biomass of 1466.7wwt.g/m$^2$. Annelida was density-dominant faunal group with a mean density of 818ind/m$^2$, comprising of 49.6% of the total density of the macrobenthos. It was followed by Mollusca with 660ind/m$^2$(40.0%). Mollusca was biomass-dominant faunal group. Major dominant species in the number of individual were Ruditapes philippinarum (375ind/m$^2$), Batillaria cumingi (208ind/m$^2$), Cirrformia tentaculata (167ind/m$^2$), Ceratonereis erithraeensis (151ind/m$^2$), Capitella capitata (111ind/m$^2$) and Sigambra tentaculata (91ind/m$^2$). Major dominant species in the biomass were Ruditapes philippinarum (1156.6wwt.g/m$^2$), Batillaria cumingi (111.0wwt.g/m$^2$) and Cyclina sinenis (106.2wwt.g/m$^2$). The species diversity was increased gradually during the study period. Increasing of species diversity was due to not only increasing of number of species but also decreasing of dominance of some polycheates. Contents of silt-clay was increased gradually in the intertidal zone.

• Journal of Aquaculture
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• v.21 no.2
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• pp.111-122
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• 2008

This study was conducted to assess the usefulness of the temperature characteristics of the tidal flat sediments during low tide as a environmental factor, and burrowing behaviour, fatness, total hemocyte counts(THCs) and differential hemocyte counts(DHCs) of hard clam Meretrix lusoria as biological activity indices for the management of hard clam farms located in Taean(Chungnam province) and Gimje(Jeonbuk province) tidal flat in Korea. Temperature ranges of the sediment at 1cm depth during spring(March to May) and summer(June to August) in Taean(where the exposure time was about $5.5{\sim}6$ hours during low tide) were $8.7{\sim}26.8^{\circ}C\;and\;27.6{\sim}32.8^{\circ}C$, respectively. Even though there was no significant difference(P>0.05), temperatures of the surface sediment where submerged with remained seawater were generally higher than that of uncovered with seawater. Burrowing depths of normally digged hard clams were 0.9{\sim}3.6cm from March to October, 2002. In the field experiment performed at Taean farming ground covered with seawater, burrowing times of the clams under natural water temperatures were $41.6{\pm}10minutes$ in February and $5.4{\pm}1.3minutes$ in August, respectively, and these were influenced by water temperatures. Fatness of hard clams began to decrease from May(at Taean tidal flat) and June(at Gimje tidal flat), showed the lowest level in August and increased again from September. Total hemocytes counts in the hemolymph of the hard clams were decreased to the lowest level in July($24.7{\times}10^4cells/mL$, at Taean tidal flat) and August($28.2{\times}10^4cells/mL$, at Gimje tidal flat), and significantly increased again from September(at Taean tidal flat, P<0.01) and October(at Gimje tidal flat, P<0.001), respectively. We observed three types of hemocytes from the hemolymph of hard clams according to whether hemocytes retain the granules or not and the size of the granules. As a results, we could found that periodical monitoring of the sediment temperatures, clam burrowing behaviour and hemocyte parameters were very helpful for the management of hard clam farming.