IMPACTS OF SEA-LEVEL RISE ON DELTAS IN THE GULF-OF-MEXICO AND THE MEDITERRANEAN - THE IMPORTANCE OF PULSING EVENTS TO SUSTAINABILITY

In deltas, subsidence leads to a relative sea-level rise (RSLR) that i s often much greater than eustatic rise alone. Because of high RSLR, d eltaic wetlands will be affected early by an acceleration of eustatic sea-level rise. If there is sufficient vertical accretion, wetlands ca n continue to exist with RSLR; however, lack of sediment input eventua lly leads to excessive water logging and plant death. Areas with low t idal range, such as the Mediterranean and Gulf of Mexico, are especial ly vulnerable to rising water levels because the elevational growth ra ng of coastal vegetation is related to tide range. Reduction of suspen ded sediments in rivers and prevention of wetland flooding by river di kes and impoundments have reduced sediment input to Mediterranean and Gulf of Mexico deltaic wetlands. This sediment deficit will become mor e important with an acceleration in sea-level rise from global warming . Most sediment input occurs during strong pulsing events such as rive r floods and storms, and management policies and decisions are especia lly designed to protect against such events. Management approaches mus t be reoriented to take advantage of pulsing events to nourish marsh s urfaces with sediments. We hypothesize that deltas can be managed to w ithstand significant rates of sea-level rise by taking advantage of pu lsing events leading to high sediment input, and that this type of man agement approach will enhance ecosystem functioning.