Oxygen and carbon dioxide exchange in the polychaete Nereis virens: influence of ventilation activity and starvation

Abstract

The influence of ventilation activity and starvation on O₂ uptake and CO₂ production in the polychaete Nereis virens Sars was investigated during September 1986 using worms collected on intertidal flats outside the Nærå Strand estuary, Denmark. The activity level, measured as ventilation rate, $\dot V\prime _W$, was linearly related to active O₂ uptake, $\dot V\prime _{_{O_2 } }$, for worms inhabiting artificial burrows (i.e. tubes) in the laboratory. $\dot V\prime _{_{O_2 } }$ at 16°C was two and four times the extrapolated standard O₂ uptake ($\dot V\prime _W$=0) when $\dot V\prime _W$ was 100 and 500 ml g^-1 h^-1, respectively. The use of tubes had no significant effect on N. viren's temporal ventilation pattern, D_v, compared to natural burrows in sediment. The ventilation rate, $\dot V\prime _W$, however, was 2 to 3 times higher in tubes than in burrows. Starvation affected both ventilation and gas exchange. $\dot V\prime _W$ increased slightly during the first six days remaining constant thereafter. D_v, on the othe hand, decreased during the first six days followed by a gradual increase to Day 20. The observed decrease in D_v (%) from Day 0 to 1 was attributed to insufficient acclimation of the worms. The time integrated ventilation rate, $\dot V\prime _W$ × D_v, increased gradually throughout the 20 d starvation period. $\dot V\prime _{_{O_2 } }$ and $\dot V\prime _{CO_2 }$ declined rapidly during the first days of starvation. After 10 d the gas exchange reached steady levels at about 50% of the initial rate. The observed decrease in metabolic rate during starvation was explained by a rapid initial reduction in specific dynamic action (SDA) followed by a gradual exhaustion of readily available metabolic reserves, e.g. glycogen and lipids.