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首页> 外文期刊>水産增殖 >Review: the present situation of self-pollution of oyster-culture areas and some possible measures to cope with this problem
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Review: the present situation of self-pollution of oyster-culture areas and some possible measures to cope with this problem

机译：回顾：牡蛎养殖区自我污染的现状及解决这一问题的可能措施

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Matsushima Bay, one of the richest oyster-culture areas in Japan, was subject to heavy artificial eutrophication, mainly from the inflow of city and factory sewage. The physiological activity in the oyster, Crassostrea gigas, in hanging cultures in this embayment declined markedly with progressive development of the gonads; this decline in activity coincided with eutrophication-induced accumulation of fatty material in the epithelia of the digestive organs; the oyster was thereby forced to depend on these accumulated fats for respiratory substrates in order to maintain its increased physiological needs. However, the fats were inefficient energy sources for the oyster and hence, during each spawning season, 50% mortality occurred. In addition, such phenomena as overmaturation of the gonad and disturbance of the lipid and steroid metabolism seemed to accelerate this mass mortality. The progress of eutrophication in recent years is due not only to an increase in the inflow of city and factory sewage, but also to an expansion of aquaculture areas in coastal waters. Dense cultivation can markedly accelerate eutrophication, especially in a small bay or inlet, leading to deterioration or self-pollution of culture areas. In a eutrophic embayment or inlet, the inflow of organic matter and the sedimentation of dead organisms often lead to an increase in organic content of the sea-bottom sediments. In summer, oxidative decomposition of these organic substances results in decrease of dissolved oxygen of both the water layers near the bottom and the intermediate stratum, with liberation of free hydrogen sulphide. The oysters naturally fail to survive in such an environment. A high density that is artificially created can result in symptoms of intraspecific physiological stress. Dense oyster culture in an area often facilitates the introduction and propagation of new strains of bacteria or parasites that were never present before. This sometimes causes disruption in the structure and function of the ecosystem. Hence, one must take precautions against artificial eutrophication of coastal waters and dense oyster culture in order to maintain steady production of oysters by means of hanging cultures.
机译：松岛湾是日本最丰富的牡蛎养殖区之一，遭受了严重的人工富营养化，主要来自城市和工厂污水的流入。随着性腺的逐步发展，在这种巢穴中，牡蛎（Crassostrea gigas）在垂吊养殖中的生理活性显着下降。活性下降与富营养化诱导的消化器官上皮中脂肪物质的积累相吻合;因此，牡蛎被迫依靠这些积累的脂肪作为呼吸底物，以维持其增加的生理需要。但是，脂肪是牡蛎的低效能源，因此，在每个产卵季节，发生了50％的死亡率。另外，诸如性腺的过度成熟以及脂质和类固醇代谢的紊乱等现象似乎加速了这种大量死亡。近年来，富营养化的进展不仅是由于城市和工厂污水的流入量增加，而且还由于沿海水域的水产养殖面积的扩大。密集种植会显着加速富营养化，尤其是在小海湾或小进口处，导致养殖区恶化或自污染。在富营养化的沉积物或入口中，有机物的流入和死生物的沉积通常导致海底沉积物的有机物含量增加。在夏季，这些有机物质的氧化分解会导致底部和中间地层附近水层的溶解氧减少，并释放出游离硫化氢。牡蛎在这样的环境中自然无法生存。人工创建的高密度可能导致种内生理应激的症状。在一个地区进行密集的牡蛎养殖通常有助于引入和繁殖从未有过的新细菌或寄生虫菌株。有时这会破坏生态系统的结构和功能。因此，必须采取预防措施，防止沿海水域的人工富营养化和密集的牡蛎养殖，以通过悬挂式养殖维持牡蛎的稳定生产。

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