Age-dependent Bioturbation of Deep-sea Sediments: Tests of Mechanisms at Three Bathyal Sites

小行星9527382 动物的摄食和移动造成的沉积物混合的机制和速率，称为生物扰动，可能会深刻影响深海海底的化学循环、微地层学和动物群落结构。 最近对底栖动物摄食的研究表明，它们消耗新沉积的高有机颗粒。 如果这种选择性进食是 基于单一生物扰动示踪剂的生物地球化学模型普遍存在，对生物扰动、微生物代谢、沉积物成岩作用和地层形成的预测不可靠。 本研究将测试三种替代的，机械的假设：测定ratiotracker活动在沉积物饲养肠道和沉积物颗粒的各种大小。具体而言，示踪剂依赖性混合可能导致（1）大小依赖性摄取Th- 234丰富的颗粒的存款馈线，（2）选择性摄取年轻的，食物丰富的颗粒的存款馈线，独立的大小，或（3）被动级联和/或主动隔离的新沉积的颗粒在动物洞穴。 ***

9527382 DeMaster The mechanisms and rates of sediment mixing by the feeding and movements of animals,termed bioturbation, may profoundly influence chemical recycling, microstratigraphy, and faunalcommunity structure at the deep-sea floor. Recent studies of ingestion by bottom-dwelling fauna suggest they consume newly sedimented, highly organic particles. If such selective feeding is widespread, biogeochemical models, based on single bioturbation tracers, would provide unreliable predictions about bioturbation, microbial metabolism, sediment diagenesis, and strata formation. This study will test three alternative, mechanistic hypotheses by: assaying ratiotracer activities in deposit-feeder guts and on sediment particles of various sizes. Specifically, tracer-dependent mixing may result from (1) sizedependent ingestion of Th- 234-rich particles by deposit feeders, (2) selective ingestion of young, food-rich particles by deposit feeders, independent of size, or (3) passive cascade and/or active sequestering of newly deposited particles in animal burrows. ***