ORIGINS AND OXYGEN CONSUMPTION OF PARTICULATE ORGANIC MATTER DEPOSITING IN OYSTER FARMS
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- HATAKEYAMA Yuji
- 東北大学大学院 工学研究科
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- KAWAHATA Tatsuya
- 東京都 下水道局
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- NISHIMURA Osamu
- 東北大学大学院 工学研究科
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- SAKAMAKI Takashi
- 東北大学大学院 工学研究科
Bibliographic Information
- Other Title
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- 内湾のカキ養殖場における沈降有機物の起源と酸素消費速度
- ナイワン ノ カキ ヨウショクジョウ ニ オケル チンコウ ユウキブツ ノ キゲン ト サンソ ショウヒ ソクド
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Abstract
<p> Suspended oyster aquaculture is one of sources of particulate organic matter (POM) potentially facilitating formations of hypoxia in bottom water of inner bays. While non-feeding oyster aquaculture is generally considered to less affect surrounding environments, substantial amount of POM, such as feces, pseudofeces and exfoliated sessile-organisms on oyster shells and aquaculture facilities deposit to sea bottom. We examined the chemical compositions (carbon and nitrogen stable isotopes, fatty acid compositions) and oxygen consumption rate of POM depositing inside and outside oyster farms in Shizugawa Bay. As a result, the local depositional flux of POM was 2 to 18 times larger inside oyster farms than outside them. It was also found that both the oxygen consumption rate per particulate organic carbon (POC) and the amount of algae fatty acid per POC of depositing POM was lower inside the oyster farms than outside them. Furthermore, those of depositing POM were also lower than those of oyster biodeposits and sessile organisms on oyster shells and farming facilities. These results demonstrate that in the oyster farms, labile fractions of POM was decomposed and significantly reduced in the sedimentation process, and POM depositing to sea floor had relatively higher contents of refractory fractions of POM as well as lower rates of oxygen consumptions per unit mass of POM. It was further estimated that the oxygen consumption of POM from oyster farms accounted for ca. 10% of the total oxygen consumption in the entire area of the inner part of the bay on average.</p>
Journal
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- Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research)
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Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research) 75 (7), III_289-III_298, 2019
Japan Society of Civil Engineers