Development of a New Technique for Quantifying Selective Ingestion of Diatoms by Deposit Feeders

9314338迈耶存款饲养者通常占主导地位的底栖生物群落在软底沉积物。 因为它们以矿物颗粒、微生物和碎屑的有机稀释混合物（通常为5%的有机物）为食，它们处理大量的沉积物以获得足够的营养。 选择性地摄取沉积物中更有营养的成分（例如，硅藻）是其摄食行为的潜在重要部分。 它还对有机物的分解、沉积物地层学以及沉积物中有机物和污染物的迁移产生了深远的影响。 然而，定量的选择性摄入的de-abundant饲养者是阻碍了方法上的问题。 该研究项目的目标是开发一种新技术，用于量化存款饲养者选择性摄取硅藻（沉积物的重要营养成分）的程度。 该项目开发的技术涉及用放射性同位素68 Ge（Si的代谢类似物）标记硅藻的基本惰性组分（硅藻壳），从而使68 Ge成为硅藻的保守放射性示踪剂。 因此，硅藻的选择性摄入可以通过比较粪便中的放射性标记浓度与试验沉积物中的放射性标记浓度来量化。 该项目将制定标记硅藻和制备闪烁计数样品的规程。 此外，在何种程度上的68锗活性的硅藻作为一个保守的放射性示踪剂和技术的灵敏度将进行评估。 最后，开发的方法将被应用到量化的选择性摄取硅藻的一种存款馈线。 ***

9314338 MAYER Deposit feeders typically dominate benthic communities in soft bottom sediments. Because they feed on the organically dilute mixture (typically 5% organic matter) of mineral grains, micro- organisms, and detritus, they process large volumes of sediment to obtain sufficient nutrition. Selective ingestion of the more nutritious components of sediment (e.g., diatoms) is a potentially important part of their feeding behavior. It also has profound ramifications for decomposition of organic matter, sediment stratigraphy, and the transport of organic matter and pollutants in sediment. However, quantification of selective ingestion by de- posit feeders is hampered by methodological problems. The goal of this research project is the development of a new technique for quantifying the degree to which deposit feeders selectively ingest diatoms, an important nutritional component of sediments. The technique to be developed by this project involves labeling an essentially inert component of diatoms (the frustule) with the radioactive isotope 68Ge(a metabolic analog of Si) such that incorporated 68Ge becomes a conservative radiotracer for diatoms. Consequently, selective ingestion of diatoms can be quantified by comparing the concentration of the radiolabel in fecal material with that in test sediment. This project will develop protocols for labelling diatoms and preparing samples for scintillation counting. Also, the degree to which the 68Ge activity of diatoms acts as a conservative radiotracer and the sensitivity of the technique will be evaluated. Finally, the developed method will be applied to quantify the selective ingestion of diatoms by one species of deposit feeder. ***