Contribution of coral reef mucus to the colloidal organic pool in the vicinity of Discovery Bay, Jamaica, W.I.

Amino acid contents of colloidal material from water adjacent to a coral reef are similar to those of mucus exudate from an incubated coral (Acropora sp.). The major amino acids (68 mole %) are glycine, aspartic acid, alanine, glutamic acid and serine. The primary lipids in colloidal coral mucus exudates are palmitic acid (16:0, 38% of total) and palmitoleic acid (16:1, 21% of total). Combined amino acids in the colloidal fraction (>1.2 nm) of 0.45 μm filtered water from Discovery Bay, Jamaica, W.I. account for less than 2% of the total organic carbon (TOC). The amount of colloidal nitrogen decreases from the Island margin, whereas the amount of total carbon increases as the water passes over the reef crest. An incubated coral head produced the equivalent of 0.60 μg N/liter of colloidal organic nitrogen or approximately 0.04 μmole N/liter. This is more than two full orders of magnitude lower than the total carbon produced (>0.25 mg/liter) in the same period. These results suggest that even in the presence of a continuous source of groundwater nitrate, the coral community tends to conserve organic nitrogen relative to carbon in exudates lost to the surrounding water.