Figure
8 .
Carbon
flow in and release from mesopelagic fish in the global open ocean. The
solid and dotted lines show the carbon flows from the ingested food and
the structural body carbon (fish body), respectively. a , diel
vertically-migrating mesopelagic fish, and b , nonmigrating
mesopelagic fish. DOC, dissolved organic carbon; CO2,
carbon dioxide; PC, particulate carbon.
Our results showed that the vertical migration of mesopelagic fish
contributes greatly to the active export of carbon. Assuming that half
of the daily food carbon release by the DVM mesopelagic fish occurs in
deep waters, the global active exports of DOC, CO2, and
PC mediated by the DVM mesopelagic fish are 0.28–4.59, 0.19–3.13, and
0.07–1.14 Pg C/y, respectively (Text S5; Table S1).
The results also showed that FC release was
approximately 3.7 times as much as BC release(Table 1). For all the DVM and NM mesopelagic fishes at both low and
high latitudes, the DOC released from food was more than 4 times higher
than that released from the fish body, and the CO2 and
PC released from food were more than 2 times higher than those released
from the fish body (Table 1).
Table 1.Carbon
release model
scenarios
for mesopelagic fish in the global open ocean. The mesopelagic fishes
were
divided
into diel vertically migrating
(DVM)
and nonmigrating (NM) groups, and the global open ocean was divided into
two regions: open oceans in 40°N–40°S, and other regions in high
latitudes up to 70°N/S.