M. Yamamuro et al., CARBON AND NITROGEN STABLE ISOTOPES OF PRIMARY PRODUCERS IN CORAL-REEF ECOSYSTEMS, Limnology and oceanography, 40(3), 1995, pp. 617-621
To examine the importance of new primary production and nitrogen fixat
ion in coral reef ecosystems, we compared delta(13)C and delta(15)N va
lues of various organic materials (coral tissues, macrophytes, particu
late organic materials, and zooplankton) from Palau (7 degrees N) and
Ishigaki (24 degrees 30'N) coral reefs in the western Pacific Ocean. T
he delta(15)N (4-6 parts per thousand) abundance of coral tissues sugg
ests that zooplankton was not the main source of N for these corals. L
ow delta(15)N values of other benthic primary producers (2-6 parts per
thousand) indicate that their nitrogen originates from nitrogen fixat
ion. These values and the high delta(13)C (-6 to -9 parts per thousand
) of macrophytes sampled at the landward part of both coral reefs lead
us to conclude that coral reef ecosystems are sinks of CO2 because of
primary production accompanied by uptake of new nitrogen.