Carbon and nitrogen fluxes in sediment inhabited by suspension-feeding (Nereis diversicolor) and non-suspension-feeding (N. virens) polychaetes

• Published in: Marine ecology. Progress series (Halstenbek) 2000-01, Vol.192, p.203-217
• Main Authors: Christensen, Bjarne, Vedel, Anders, Kristensen, Erik
• Format: Article
• Language: English
• Subjects: Algae; Marine; Marine sediments; Nereis diversicolor; Nereis virens; Nitrogen; Phytoplankton; Sediments; Solutes; Stoichiometry; Suspended solids; Ventilation systems; Worms
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps192203

The impact of suspension-feeding Nereis diversicolor and non-suspension-feeding N. virens on C and N dynamics in an organic-poor sediment was investigated in a controlled laboratory study simulating periods of high and low phytoplankton (Rhodomonas sp.) concentration. High phytoplankton concentration resulted in a 30-fold higher deposition (clearance) of particulate C and N to the sediment inhabited by N. diversicolor than to N. virens and defaunated sediment. Concurrently, O2 consumption and NH4+ + NO3- release were increased by a factor of 3 in sediment with N. diversicolor, but only by a factor of about 1.5 in N. virens and defaunated treatments. Steady-state porewater concentrations of TCO2 and NH4+ decreased exponentially with increasing ventilation activity of nereids. Ventilation activity was highest for suspension-feeding N. diversicolor and lowest for deposit-feeding N. virens. About 30% of the deposited algal C and N in the N. diversicolor sediment were lost rapidly as excess CO2 or NH4+ + NO3- flux to the water column. Incorporation into N. diversicolor tissues accounted for ⅔ of the retained C and N. In the case of N. virens, where no net phytoplankton deposition occurred, organic matter removal due to mineralization resulted in a net loss of both sedimentary C and N. Accordingly, the biology and behaviour of infaunal species are important determinants for sediment biogeochemistry and element cycling in marine areas.