Radiotracer Methods For Determining Utilization of Sedimentary Organic Matter by Deposit Feeders
The purposes of this chapter are to evaluate methods to measure ingestion and absorption by deposit feeders of sedimentary organic matter, to consider the assumptions underlying these methods, and to recommend approaches to develop better methods. Deposit feeders acquire food by ingesting large volumes of sediment and absorbing some fraction of the organic matter. Particle-associated microorganisms are generally absorbed well but are not abundant enough in sediment to account for very much of the absorbed organic matter (Cammen, 1980a and this volume; Lopez and Levinton 1987). Deposit feeders are therefore digesting and absorbing some fraction of the detrital sedimentary organic matter. The refractory nature of much of the sedimentary organic matter results in low absorption efficiency. Gravimetric and chemical methods of estimating organic absorption reach their limits of resolution at the lower range of absorption; it is very difficult to distinguish 5% from 0% absorption, although it is obviously of great consequence to the animal. The difficulty in accurately measuring organic absorption by deposit feeders is compounded by selective ingestion of the organic fraction of sediment. Therefore the study of the utilization of sedimentary organic matter by deposit feeders should include methods for accurately determining absorption efficiency and ingestion selectivity.
KeywordsFecal Pellet Organic Fraction Absorption Efficiency Sedimentary Organic Matter Deposit Feeder
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- Brock, T.D. 1978. The poisoned control in biogeochelnical investigations. pp. 717–725, IN W.G. Krumbein, ed., Environmental Biogeochemistry and Geomicrobiology vol. 3. Ann Arbor Sci., Ann Arbor.Google Scholar
- Calow, P. and C. R. Fletcher 1972. An new radiotracer technique involving C and Cr for estimating the assimilation efficiency of aquatic primary producers. Oecologia (Berl.), 9: 155–170.Google Scholar
- Cammen, L. M. 1980a. The significance of microbial carbon in the nutrition of the deposit feeding polychaete Nereis succinea. Mar. Biol. 61: 9–20.Google Scholar
- Canimen, L. M. 1980b. Ingestion rate: An empirical model for aquatic deposit feeders and detritivores. Oecologia (Berl.) 44: 303–310.Google Scholar
- Sequi, P. and R. Arenghieri 1977. Destruction of organic matter by hydrogen peroxide in the presence of pyrophosphate and its effects on soil specific surface area. Soil Sci. Soc. Am. J. 41: 340–342.Google Scholar