Dredging and Shipping Impacts on Southeast Florida Coral Reefs

Many coastal regions have experienced extensive population growth during the last century. Commonly, this growth has led to port development and expansion as well as increased vessel activity which can have detrimental effects on coral reef ecosystems. In southeast Florida, three major ports built in the late 1920’s along 112 km of coastline occur in close proximity to a shallow coral reef ecosystem. Recent habitat mapping data were analyzed in GIS to quantify the type and area of coral reef habitats impacted by port and shipping activities. Impact areas were adjusted by impact severity: 100% of dredge and burial areas, 75% of grounding and anchoring areas, and 15% of areas in present anchorage. Estimates of recent local stony coral density and cover data were used to quantify affected corals and live cover. After adjusting for impact severity, 312.5 hectares (ha) of impacted coral reef habitats were identified. Burial by dredge material accounted for 175.8 ha. Dredging of port inlet channels accounted for 84.5 ha of reef removal. And 47.6 ha were impacted from a large ship anchorage. Although the full extent of all ship groundings and anchor drags associated with the ports is unknown, the measured extents of these events totaled 6 ha. Based on the adjusted impact areas, over 8.1million corals covering over 11.7 ha of live cover were impacted. Burial impacts were the greatest. The planned expansion of two of the ports would remove an additional approximate 9.95 ha of coral reef habitat. Ongoing marine spatial planning efforts are evaluating the placement of large ship anchorages in an effort reduce future impacts from ship anchoring. However, increasing populations and shipping needs will likely continue to be prioritized over protection of these valuable natural resources.