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Marine Ecology Progress Series

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MEPS 679:31-45 (2021)  -  DOI:

Temperature effects on carbon mineralization of sinking copepod carcasses

Belén Franco-Cisterna1,*, Peter Stief1, Ronnie N. Glud1,2,3

1HADAL & Nordcee, Department of Biology, University of Southern Denmark, 5230 Odense, Denmark
2Department of Ocean and Environmental Sciences, Tokyo University of Marine Science and Technology, 108-8477 Tokyo, Japan
3Danish Institute for Advanced Study (DIAS), University of Southern Denmark, 5230 Odense, Denmark
*Corresponding author:

ABSTRACT: Copepod carcasses are prevalent in marine ecosystems and might represent an important component of the sinking flux of particulate organic carbon in the ocean. The extent to which copepod carcasses contribute to the biological carbon pump is controlled by different environmental factors, including temperature. However, the effect of temperature on the longer-term kinetics of carbon mineralization of copepod carcasses is not well-studied. We conducted laboratory experiments to quantify the carbon mineralization associated with sinking carcasses of the cosmopolitan copepod Acartia tonsa through aerobic microbial respiration at 5 temperatures (20, 16, 12, 8, and 4°C). Microbial respiration rates associated with the carcasses were positively correlated with temperature and characterized by an initial short lag-phase, a rapid increase to a maximum rate, and a subsequent gradual decline in the rate of degradation. On average, 50% of the total carbon of the carcasses was mineralized within 6-12 d at 20°C, versus >60 d at 4°C. During the incubations, most carbon mineralization occurred in the ambient seawater, likely fueled by dissolved organic carbon leaking from the carcasses into the surrounding seawater. Extrapolating measured carbon turnover and sinking rates suggests that at 20°C, the mineralization of sinking copepod carcasses is constrained to the surface ocean. In contrast, at 4°C, sinking copepod carcasses can reach the deep ocean before they have been completely degraded. Hence, in low-temperature regions, copepod carcasses may represent an important agent for carbon export through the biological carbon pump.

KEY WORDS: Biological carbon pump · Marine snow · Copepods · Acartia tonsa · Temperature · Oxygen · Carbon · Degradation · Respiration

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Cite this article as: Franco-Cisterna B, Stief P, Glud RN (2021) Temperature effects on carbon mineralization of sinking copepod carcasses. Mar Ecol Prog Ser 679:31-45.

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