Anthropogenic disturbance of Caribbean mangrove ecosystems: Past impacts, present trends, and future predictions

We review historical, current, and projected future impacts of four classes of anthropogenic disturbance-extraction, pollution, reclamation, and changing climate-on Caribbean mangrove ecosystems (mangal). These disturbances occur, respectively, at increasing spatial and temporal scales, and require increasing recovery rime. Small-scale selective extraction has little system-wide effect, but regeneration is slow even on single hectare clear-cuts due to rapid soil acidification. Petroleum is the primary pollutant of Caribbean mangal, and results in tree defoliation, stand death, and loss of associated sessile and mobile animal species. Hydrocarbons persist in mangrove sediments for decades, and are correlated with increasing seedling mutation rates. Chemical, industrial, and urban wastes are associated with increased heavy metal content of seedlings, stand die-back, reduced system-wide species richness, and higher incidence of Vibrio spp. (shellfish poisoning). Mangal has been reclaimed for urbanization, industrialization, and increasingly, for tourism. Overall, the region is losing mangrove forests at approximate to 1 percent per yr, although the rate is much faster on the Caribbean mainland (approximate to 1.7% yr(-1)) than it is on the islands (approximate to 0.2% yr(-1)). The region's fisheries are declining at a similar rate, as most commercial shellfish and finfish use mangal for nurseries and/or refugia. Few Caribbean states have legislation or enforcement capabilities to protect or manage mangal, although at least 11 international treaties and conventions could be applied to conserve or sustainably use these forests. These treaties may protect riverine and basin mangal, but are likely to be moot with respect to fringing mangal, which may vanish as a consequence of global climate change. Growth enhancements of mangroves resulting from increasing atmospheric CO2 probably will not compensate for negative effects of concomitant rises in regional sea level.