EFFECTS OF CHRONIC OIL-SEDIMENT POLLUTION ON THE REPRODUCTION OF THE CARIBBEAN REEF CORAL SIDERASTREA-SIDEREA

In 1986 a major oil spill in Panama polluted and killed extensive areas of coral reefs. Five years afterwards, reef areas are chronically threatened by oil and large amounts of sediments containing toxic hydrocarbons trapped in mangroves. Sublethal effects of oil on coral reproduction were evaluated 39 months after the spill using healthy and injured colonies of the reef-building coral Siderastrea siderea at heavily oiled and unoiled reefs. Number of reproductive colonies and number of gonads per polyp were not sensitive to level of oiling, but gonads were significantly larger at unoiled than oiled reefs during spawning periods. Colonies with recent injuries demonstrated a consistent decrease in fecundity relative to uninjured parts of the same colonies. Years after the spill, the increased number of injuries and associated reduction in colony size, and decreased size of gonads (eggs) on oiled reefs can reduce the number of reproductively viable colonies and gametes in coral populations, and ultimately reduce population survival.