Figure
7 .
Relative
contributions of different forms of carbon to the released body carbon
over the 8-d depuration period with different daily food rations
(a ) and the allocation of the released body carbon of marine
medaka (b ). Data are the mean ± SD (n =3–5). The error bars
represent the standard deviations. DOC, dissolved organic carbon;
CO2, carbon dioxide; PC, particulate carbon. The food
rations are expressed as a percentage of the fish dry weight (DW). The
values in brackets in subfigure (b) indicate the means of the
above-noted ranges.
3.4
Carbon release from mesopelagic fish estimated using the carbon release
model
The results showed that DVM mesopelagic fish ate 1.51–25.2 Pg
zooplankton carbon and released 0.59–9.84
Pg
C DOC, 0.42–6.95 Pg C CO2, and 0.15–2.56 Pg C PC
annually in the global open ocean (Figure 8a). NM mesopelagic fish
ingested and released similar amounts of carbon annually (Figure 8b, and
see details in Text S5).
In total, of the 3.41–38.8 Pg zooplankton carbon ingested by all
mesopelagic fishes per year in the global open ocean, 1.33–15.1 Pg of
the ingested carbon was assimilated in the fish body, whereas the
remaining unassimilated carbon was released as DOC (1.12–12.7 Pg C/y),
CO2 (0.71–8.10 Pg C/y), and PC (0.26–2.91 Pg C/y) in
seawater. Meanwhile, 0.57–6.30 Pg body carbon of the mesopelagic fish
was lost annually as DOC
(0.23–2.55
Pg C/y), CO2 (0.24–2.69 Pg C/y), and PC (0.10–1.07 Pg
C/y). That is, mesopelagic fish in the global open ocean annually
released
1.34–15.2,
0.95–10.8, and 0.35–3.97 Pg C in the forms of DOC,
CO2, and PC, respectively.