中文摘要：

通过实验室可控条件,以桑沟湾（Sanggou Bay）养殖海带（Sacharina japonica）为研究对象,探讨养殖海带碎屑降解过程中营养盐释放速率及对底质、溶解氧的影响。实验设置2个底质条件（加底泥,无底泥）、2个溶氧条件（好氧,厌氧）,各处理组设3个平行,实验持续27 d。结果显示,（1）加入底泥,可以促进海带碎屑的降解。实验结束时,加入底泥组无机氮（DIN）、总氮（TN）、活性磷酸盐（DIP）、总磷（TP）的平均释放速率分别为1.234、1.802、0.028、0.033μmol/（g·d）,显著高于未加底泥组的0.039、1.476、0.005、0.010μmol/（g·d）。而未加底泥组的可溶性有机氮（DON）释放速率为1.437μmol/（g·d）,显著高于底泥组的0.568μmol/（g·d）。（2）厌氧条件有利于海带碎屑中P的降解释放,释放的TP中以可溶性有机磷（DOP）为主。TP、DIP、DOP的降解速率显著高于非厌氧条件。但是,厌氧条件下无机氮释放速率为0.097μmol/（g·d）,仅为好氧条件下无机氮的8%,而总氮为好氧条件下的71%。（3）底泥的加入显著提高了水体的N∶P,达到207.83±301.37,厌氧状态使水体N∶P降低到9.38±6.55,都较大的偏离对照组的16.82±1.26,远远偏离经典Redfield值（16∶1）。整个实验说明养殖海带降解过程受底质、溶氧条件影响,同时,大量海带碎屑腐烂降解,将会对养殖系统的营养盐浓度及结构产生影响。

英文摘要：

When mariculture Sacharina japonica decay, a large amount of nutrients will be released into the ocean, which will affect the stability in the marine ecosystem. In a 27-day experiment, we investigated the decay rate of Sacharina japonica in the Sanggou Bay and how this process be affected by environmental condition. To determine the effects of the sediment and dissolved oxygen（DO）, we set up two conditions including the sediment-containing group and the sediment-free group, and other two conditions about DO including aerobic or anaerobic group. Fluxes of DIN, DON, TN, DIP, DOP and TP were determined during the incubation period. The results were shown as follows：（1） At the end of experiment, the fluxes of DIN, TN, DIP and TP in sediment-containing group were 1.234, 1.802, 0.028, and 0.033 μmol/（g？d） respectively, which were significantly higher than those in the sediment-free group, suggesting that sediment could promote the decay of kelp. However, the flux of DON [0.568 μmol/（g？d）] was significantly lower than that of the sediment-free group.（2） Anaerobic conditions facilitated the release of P from kelp debris and more DOP was released than DIP. The decay rates of TP, DIP and DOP were significantly higher in the anaerobic conditions. However, the release rate of DIN and TN [0.097 μmol/（g？d）] under anaerobic conditions was only 8% and 71% of those under aerobic conditions respectively.（3） The N：P ratio significantly increased to 207.83±301.37 in the sediment-containing group, whereas it decreased to 9.38±6.55 under the anaerobic condition, both of which were distinct from the control group 16.82±1.26. These values were also largely different from the value of Redfield（16：1）. Our results suggested that the decay of S. japonica detritus was a fast process and that intensified detritus decay could alter the concentrations and structure of nutrients.