MASS MORTALITY OF THE TROPICAL SEAGRASS THALASSIA-TESTUDINUM IN FLORIDA BAY (USA)

This report documents rapid and widespread mortality of the seagrass Thalassia testudinum Banks ex Konig (turtle grass) in Florida Bay at the southern tip of the Florida peninsula (USA). More than 4000 ha of seagrass beds have been completely lost in recurring episodes of mortality since summer 1987. An additional 23 000 ha have been affected to a lesser degree. Loss of T. testudinum, the dominant macrophyte species in this highly productive system, may affect ecosystem function within the bay as well as estuarine-dependent sport and commercial fisheries. A pathogenic protist related to the causal agent of the eelgrass wasting disease may be involved in the mortality and may place T. testudinum populations outside Florida Bay at risk. Environmental factors and chronic hypoxia of below-ground T. testudinum tissue may also contribute to the die-off.