Several experiments were carried out to provide new information on the use of the 14C formaldehyde technique in deposit-feeding studies. Our results show that: (1) uptake and stability of labelling vary with species and types of detritus, (2) there are significant differences between the labelling stabilities of uniformly and 14C formaldehyde labelled diatoms, (3) the use of uniformly and 14C formaldehyde labelled detritus derived from Pavlova lutheri results in very similar ingestion rates and absorption efficiencies by Abra ovata, (4) ingestion rates and absorption efficiencies of Abra ovata fed on 11 macrophytobenthic types of detritus labelled with 14C formaldehyde are consistent with the literature (negative relationship between ingestion and protein content, and between absorption and phenolic content), and (5) absorption efficiencies recorded for 14C formaldehyde labelled sediment trap materials collected at different periods of the year correlate negatively with gross sedimentation rates. These results support the use of the 14C formaldehyde technique with monospecific detritus. The relative values of absorption efficiencies recorded for heterogeneous detritus also seem consistent. However, it is stressed that the exactitude of the absolute values of these absorption efficiencies is yet to be proven.
Radiotracer techniques . Sedimentary organic matter . Absorption efficiency . Deposit-feeder . 14C formaldehyde
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