Synthesis towards a global-bathymetric model of metabolism and chemical composition of marine pelagic chaetognaths

摘要

Respiration (=oxygen consumption) and chemical composition [water content ash, carbon (C) and nitrogen (N)] were determined for seven chaetognaths (Parasagitta elegans, Caecosagitta macrocephala, Pseudosagitta scrippsae, Solidosagitta zetesios, Eukrohnia hamata, Eukrohnia bathypelagica and Eukrohnia fowleri) from the epipelagic through bathypelagic zones (<3000 m) in the western subarctic Pacific Ocean. Enzyme activities of the electron transfer system (ETS) were also determined on mesopelagic and bathypelagic chaetognaths, and ETS:Respiration ratios were calculated to confirm the validity of respiration rates measured at near in situ temperature but under normal pressure (1 atm). These data were combined with literature data from Arctic, Antarctic, temperate and tropical waters, and epipelagic through bathypelagic zones. A total of 25 data sets on 17 chaetognaths for respiration, and a total of 18-34 data sets on 18-21 chaetognaths for chemical composition were used to explore important parameters affecting their respiration rates and chemical composition. Designating body mass (dry mass, C or N), ambient temperature, oxygen saturation and sampling depth as independent variables, stepwise multiple regression analyses revealed that body mass, habitat temperature and sampling depth were significant attributing 82-93% of the variance of respiration rates. No significant effect of sampling depth and habitat temperature was detected in the chemical composition. These results are compared with those of copepods to highlight unique features of chaetognaths.