Carbon isotopes of essential amino acids highlight greater contribution
of far-field vs near-field subsidies to predators on oceanic coral reefs
Reef predators are partly sustained by oceanic production sources, but
the pathways through which this occurs remain poorly understood. Studies
exploring reef-pelagic linkages have used bulk stable isotopes, yet
these have limited power to discriminate between major source types. We
used δ13C values of essential amino acids (δ13CEAA), which can better
resolve different modes of carbon acquisition, to trace the origin of
the carbon sources sustaining reef predator biomass in the Maldives.
White muscle tissue was sampled from four key fishery target groupers
and eight primary consumer species (representing six energy pathways).
Primary consumer δ13CEAA values separated into four distinct clusters:
1) algae/detritus, 2) coral, 3) reef plankton, and 4) pelagic plankton.
Bayesian stable isotope mixing models identified pelagic plankton as
primarily sustaining all four groupers across the atoll, indicating that
oceanic nutrients are available throughout and that these reefs may be
more resilient to bleaching-induced loss of live coral.