Effects of Bioturbation by Macrobenthos Living on the Tidal Flat on the Bottom-Mud Environment and Concentration Profiles of Nutrient Salts

根据野外测量和分析资料，研究了潮间带大型底栖动物的生物扰动对底栖环境的影响和营养盐的浓度分布。主要研究结果如下：1.掌握了研究点大型底栖动物的种类及其数量分布。此外，还发现潮滩表面大型底栖动物及其巢穴的数量分布受空气和泥浆温度的影响很大。底泥的氧化还原电位(Eh)与大型底栖动物及其巢穴的数量分布密切相关。因此，推测底泥中对环境影响最大的生物扰动是大型底栖动物的筑巢作用。据估算，底泥中氧化层和还原层的垂直分布随潮汐和洪水的变化以及大型底栖动物生物扰动强度的变化而发生明显的周期性变化。大型底栖动物及其巢穴的数量分布与底泥中Eh的垂直分布和底泥孔隙水中NH_4~(++)、NO_3~(-)的浓度密切相关。推测底泥中有机质的分解和矿化，即底泥中细菌产生营养盐的过程，是在潮涨潮落的环境变化和底泥中大型底栖动物筑巢成洞的情况下有效进行的。从理论和实验上阐明了波流联合作用下底泥的再悬浮机理，这是影响底泥中营养盐浓度分布的物理作用之一。

The effects of bioturbation by macrobenthos living on the tidal flat on the environment in the bottom-mad and the concentration profiles of nutrient salts were investigated on the basis of field measured and analytical data. The results obtained by this research are summarized as follows :1. The species of macrobenthos and its number distribution in the study sites were grasped. Moreover, it was found that the number distributions of macrobenthos and its nesting holes on the tidal flat surface were strongly affected by air and mud temperature.2. The close relationships were observed between the redox potential (Eh) in the bottom-mud, and the number distributions of macrobenthos and its nesting hole. Therefore, it was assumed that the most important bioturbation that influenced on the environment in the bottom-mud was the nesting hole formation by macrobenthos.3. It was estimated that the vertical distributions of oxidized and reduced layers in the bottom-mud changed remarkably and periodically according to ebb and flood, and variation of bioturbation strength by macrobenthos.4. The close relationship was observed between the number distributions of macrobenthos and its nesting hole, and the vertical profiles of Eh in the bottom-mud and NH_4^+ and NO_3^- concentrations in the bottom-mud pore water.5. It was estimated that the decomposition and mineralization of organic matters, that is, the nutrient salts production processes by bacteria in the bottom-mud took place effectively under the environment variations that occurred according to ebb and flood, and nesting hole formation by macrobenthos in the bottom-mud.6. The resuspension mechanism of bottom-mud under the combined wave-current flows, which was one of physical action that affected on the concentration profiles of nutrient salts in the bottom-mud, was made clear theoretically and experimentally