The bioturbation structure is an important indicator of the state of the seabed environment and the main basis for the reconstruction of the paleosedimentary environment; moreover, it affects the early diagenesis of sediments and the redistribution of materials, and becomes the interference factor for the interpretation of the 100-year scale sedimentary records. In this article, sediment cores from 21 stations in the Changjiang River Estuary and its adjacent areas were characterized qualitatively and quantitatively by using high-resolution X-ray computed tomography technology, and the main factors affecting the bioturbation structures were analyzed. The result shows that the bioturbation structures in the Changjiang River Estuary and its adjacent areas are relatively developed, which can be divided into four types: biodiffusor structures, conveyor structures, regenerator structures and gallery-diffusor structures. Conveyor structures and gallery-diffusor structures are common. The bioturbation structure is distributed in various forms in the core, including exponential attenuation type, wave attenuation type, uniform distribution type, pulse distribution type and other vertical distribution forms. The depth of disturbance varies, most of which are within 20 cm, but some are more than 40 cm. The bioturbation structures are spatially uneven. The Changjiang River Estuary and the inner shelf are relatively developed, with a disturbance inventory of 0–13 972 mm3, while the northern Jiangsu coast and the middle continental shelf are less, with a disturbance inventory of 351–3 212 mm3. The bioturbation structures from the coast to the outside have a decreasing trend. The development degree of bioturbation structure is mainly restricted by the type of bottom material and sedimentation rate. Clay silt and suitable sedimentation rate (0.52–1.34 cm/a) are conducive to the development and preservation of bioturbation structures.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |