Organic matter
Organic matter could be transferred from corals to sponges by all these pathways, but DOM likely makes up the largest fraction, as the majority (56 to 80%) of coral mucus dissolves in the water column, and coral loss of fixed carbon due to expulsion of "Symbiodinium" is typically negligible (0.01%) compared with mucus release (up to ~40%). Coral-derived organic matter could also be indirectly transferred to sponges via bacteria, which can also consume coral mucus.