Reef coral populations were monitored from 1988 to 1991 at the Flower Garden Banks located in the northwestern Gulf of Mexico. The status of reef coral populations, and natural or man-made factors potentially affecting their well being were determined. Man-made chronic disturbances are degrading coral reef resources on a global scale. Yet, the Flower Garden coral reefs seem to have been widely sheltered from the effects of regional stresses generated by population growth and increased industrial activity.

Since 1974, reef coral population levels have remained unchanged in the Montastrea- Diploria Zones at the Flower Garden Banks. Live coral cover ranges between 46 and 46.5 %. Montastrea annularis and Diploria strigosa comprise 80% of the coral cover on either bank. The remainder of the cover is mostly sharedby eight other taxa even though 12 hermatypic coral species inhabit the Montastrea-Diploria Zones. P. astreoides, M. annularis, Agaricia spp. and Diploria strigosa are the most abundant species (> 80 % of colony counts).

Coral taxa appear to be more homogeneously distributed on the West Bank. The relatively greater number of Agaricia spp., Madracis decactis, and P. astreoides colonies on the East Bank may be the source of a decreased evenness. The health of reef corals was assessed using repetitive and non-repetitive photographic methods, and accretionary growth measurements of M. annularis. Reef corals have undergone small scale changes at the Flower Gardens probably reflecting natural disturbance, predation, disease, and inter-specific competition. More tissue was gained than lost in repetitive photographic quadrats. The causes to most of the tissue loss were unknown. White mat disease (ridge disease) is shown to generate more tissue loss than any of the three bleaching events that took place at the Flower Gardens (1989, 1990, and 1991). Advance to retreat linear ratios of encrusting growth revealed a net tissue gain on the East Bank and a net tissue loss on the West Bank. In situ and retrospective accretionary growth rates of M. annularis were highly variable. Retrospective growth rates (5.3 and 7.8 mm/yr) were estimated using a new method. The mean in situ growth rate was 4 mm/6 mo 13 S.D. The annual barium content from 1910 to 1989 in a M. annularis colony from the West Flower Garden did not reveal trends associated with the extensive oil and gas exploration in the northern Gulf of Mexico.