The role of sediment particle size in the nutritional energetics of a surface deposit-feeder. II. Energetic cost measured as ¹⁴C loss from uniformly labeled Hydrobia truncata (Vanatta)

Measurements of ¹⁴C loss from uniformly labeled Hydrobia truncata indicated an average energetic cost in this deposit-feeder of 1.7% of total body carbon · day^-1. ≈40-50% of carbon lost was in particulate form, while the remaining 50-60% consisted of dissolved carbon (dissolved excretory products and CO₂). Sediment particle size had no effect on total carbon loss or on the relative fractions of carbon lost in dissolved vs. particulate form. H. truncata from a sandy beach population had a higher particulate carbon loss rate and lower dissolved carbon loss rate than conspecifics from a muddy salt-marsh population. Total carbon loss did not differ between the two groups. Differences in net carbon intake by H. truncata in response to sediment particle size do not appear to be responsible for size and density distributions of field populations.