大型底栖动物对河口沉积物的扰动作用

利用微宇宙示踪技术，定量研究了天津北塘河口地区的天津厚蟹、沙蚕、泥螺和青蛤4种底栖动物对沉积物的扰动作用.结果表明：生物扰动对沉积物的分布具有明显影响.不同底栖动物扰动能力不同，对表层沉积物的扰动强度（扩散系数，10^-3 cm²·d^-1）大小依次为：沙蚕（2.95）> 天津厚蟹（1.00）> 青蛤（0.78）> 泥螺（0.35）> 对照（0.05）；对深层沉积物则是天津厚蟹（3.10）>沙蚕（2.33）>青蛤（0.28）>泥螺（0.15）> 对照（0.05）.这种差异主要与不同底栖动物所属的功能群不同有关.底栖动物体积与表层沉积物扩散系数显著相关（P<0.05），可采用底栖动物体积预测其对沉积物的扰动强度.

Bioturbation of macrobenthos on estuarine sediment

By using microcosm tracer technique, the bioturbation of macrobenthos Helice tientsinensis, Nereis diversicolor, Bullacta exarata, and Cyclina sinensi
son the sediment in Beitang Estuary of Tianjin, China was quantitatively studied. The bioturbation of test macrobenthos had obvious effects on the distribution of the sediment, and the effects differed with the macrobenthos. The disturbed intensity (diffusion coefficient, 10^-3 cm²·d^-1) of surface sediment under the effects of the macrobenthos was in order of N. diversicolor (2.95)>H. tientsinensis (1.00)>C. sinensis (0.78)>B. exarata(0.35)>control (0.05), and that of deep sediment was H. tientsinensis (3.10)>N. diversicolor (2.33)>C. sinensis (0.28)>B. exarata (0.15)> control (0.05), which was mainly due to that the macrobenthos were belonged to different functional groups. There was a significant relationship between the bio-volume of test macrobentos and the diffusion coefficient of surface sediment (P<0.05), suggesting that the bio volume of macrobenthos could be used as an indicator to predict their bioturbation capacity on esturaine sediment.