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Reexamination of food supply effectual for suspension-feeding bivalves inhabiting shallow waters.

重新审查对栖息于浅水区的悬浮喂养双壳类动物有效的食物供应。

基本信息

批准号：
16580143
负责人：
SASAKI Koichi
金额：
$ 2.18万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

Understanding of the food supply for each species is a dominant factor to determining carrying capacity in an area. In the fishing ground of the surf clam dredge fishery in Fukushima Prefecture, it was shown, 1. that most infaunal bivalves relied on the overlying water close to the bottom surface as a food source layer, extending less than several cm thick; 2. that pelagic microalgae that were produced in the upper layers rarely entered the food source layer. So, the bivalves might rarely ingest the primary production, and 3, that such food supply system was very common on sandy bottoms in sublittoral waters. These showed the primary production in the near-bottom layer play an important role as the food source for benthic communities.In the upper layers of water column dominated by pelagic microalgae, dominant species groups changed seasonally, and a relatively small number of species groups constituted a large proportion, and their density fluctuated in about a hundredfold. In contrast, the near-bottom layer that forms the food source layer showed smaller seasonal changes in dominant species groups, with low fluctuation in the density of 10-15 folds. Such properties of low fluctuation may support the stability as the food sources.The results obtained in the study showed that the food supply for infaunal bivalves differed from the conventional vague conception for it that phytoplankton produced in the upper layers sink to the bottom, forming the main food source, and that benthic microalgae, especially benthic diatoms, and phyto-detritus derived from them were the effective food sources.

了解每个物种的食物供应是确定一个地区承载能力的一个主要因素。在福岛县的浪蚌捕捞渔场，显示1。大多数底栖双壳类依赖于靠近底表面的上覆水作为食物源层，延伸不到几厘米厚; 2.上层产生的浮游微藻很少进入食物源层。因此，双壳类可能很少摄食初级生产物; 3.这种食物供给系统在近岸沃茨的桑迪底质中非常普遍。近底层初级生产力是底栖生物群落的重要食物来源;以浮游微藻为主的上层水体，优势种类群季节性变化较大，数量较少的种类群所占比例较大，密度波动在百倍左右。与此相反，近底层，形成食物源层显示出较小的优势种组的季节性变化，在10-15倍的密度波动较小。研究结果表明，底栖双壳类的食物供给不同于传统的模糊概念，其主要食物来源是上层浮游植物沉到底层，而底栖微藻，尤其是底栖硅藻及其衍生的植物碎屑是有效食物来源。