Temporal and spatial variability in metabolism of the Antarctic pelagic tunicate Salpa thompsoni Foxton, 1961

ABSTRACT

The mass-specific metabolic rates of the Antarctic pelagic tunicate Salpa thompsoni Foxton, 1961 were studied during March-April of 1998 and March 2002. The study revealed a large variation in metabolic rates and assessed sources of this variability. The main factors driving variability included density of tunicates in incubation containers (incubation density, e.g. the salp mass per unit volume of the respirometer), diel/circadian rhythms in salps, and spatial variability of their metabolic performance related to the feeding conditions. The mass specific respiration rates of both salp life forms (oozooids and blastozooids) appeared to be independent of their body mass. The salp-specific respiration rates at 3°C were strongly negatively influenced by their incubation density ranging between 2.0 and 90.4 gWW.l⁻¹. Salp respiration rates adjusted to an incubation density of 3 gWW.l⁻¹ in both oozooids and blastozooids followed similar circadian rhythms with the mean respiration rates of 79.5 and 41.5 μg O2 gWW⁻¹ h⁻¹, respectively. Deviation of these rates from actual field-measured respiration rates corrected for the salp density and diel variability during 1998 and 2002 identified effects of food concentrations, i.e. proxy of the plankton community development and composition, on the salp population performance.

KEYWORDS:

• Southern Ocean
• salps
• respiration rates
• diel variability
• spatial and temporal heterogeneity

Acknowledgements

The work was carried out within the framework of Scientific Research Programs of Russian Academy of Sciences ‘Comprehensive studies of the current state of the ecosystem of the Atlantic sector of the Antarctic’ # АААА-А19-119100290162-0, ‘Functional, metabolic, and molecular genetic mechanisms of marine organism adaptation to conditions of extreme ecotopes of the Black Sea, the Sea of Azov, and other areas of the World Ocean', Grant # 124030100137-6.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

NIM and EZS participated in the expeditions, conducted measurements, analysed the data and prepared the first Russian draft of the manuscript, EAP translated the manuscript, ran statistical tests and significantly contributed to the MS writing. All authors approved the final version of the MS.

Data availability

Raw data can be made available on reasonable request to authors.

Additional information

Funding

The study was funded by the Russian Academy of Sciences under two grants: ‘Comprehensive studies of the current state of the ecosystem of the Atlantic sector of the Antarctic’, Grant # АААА-А19-119100290162-0, and ‘Functional, metabolic, and molecular genetic mechanisms of marine organism adaptation to conditions of extreme ecotopes of the Black Sea, the Sea of Azov, and other areas of the World Ocean', Grant # 124030100137-6. This research was also partially supported by the NSERC Discovery Grant RGPIN-2014-05107 to E.A.P.