The City of Key West is considering another effort to widen the channel leading into Key West Harbor to accommodate larger cruise ships. Here are my comments on why this is not a good idea. DeeVon Quirolo dquirolo @gmail.com
Updated July 9th, 2011
Despite the implementation of best efforts to prevent it, sedimentation created by the outright removal of habitat during the project to widen the channel heading into Key West Harbor will have immediate and long term negative impacts on nearby coral reefs such as Sand Key, Rock Key and Eastern Dry Rocks.
The amount of sediment that will be generated will be significant. Not the natural sediment that is stirred up during a storm, but by the significant amount of matter created by the outright removal and destruction of the bottom and loosening of sand, coral, and rock that will be suspended and carried by the outgoing tides to the reef. There will be an immediate, complete loss of marine life to portions of the channel and harbor during the project. And there will be chronic re-suspended sediment whenever a large ship navigates the newly-excavated portions of the channel.
Whether by blasting or other means, no matter how carefully it is done and to what degree this bottom material is removed, it will generate significant turbidity and sediment that–depending on the currents– will be carried to the offshore coral reefs. The plume of sediment will cloud the water and prevent photosynthesis from occurring that reduces the conditions needed for healthy coral and marinelife. Key West Harbor is home to endangered sea turtles and dolphins. Their habitat will be degraded as well.
The sediment will cover hard and soft corals such as Elkhorn and Staghorn, branching corals that are incapable of sloughing it off. Elkhorn and Staghorn corals have been placed on the U.S. Endangered Species list. These once common corals at Eastern Dry Rocks and other local reefs have experienced massive losses that have been documented here by Craig Quirolo. Corals need clear, clean, nutrient-free waters to thrive. The coating of sediment will prevent these and other corals from feeding under such conditions and they cannot survive. This will further reduce the few remaining endangered colonies in the area and should be a major reason why the harbor should not be widened.
Soft corals such as purple sea fans will also become stuffed with sediment. Significant losses of sea fans have already been documented at Key West-area coral reefs. Sponges filter and clean the ocean and provide habitat for spiny lobster and other crustaceans. The sediment will overwhelm them as well. Seagrasses, which are protected under state and federal law, and which stabilize the ocean bottom, will be removed, causing more sedimentation.
If the dredging is done during the coral spawning period in August, it could do significant damage to corals that are attempting to propagate, as the new corals must settle on a clean surface to take hold and grow. Sediment would prevent that from happening. If permitted, no dredging should be allowed during coral spawning.
In short, dredging the channel leading to Key West Harbor to widen it for cruise ships would be a terrible idea for Key West’s coral reef ecosystem. It would further threaten endangered corals and sea turtles and destroy live bottom in existing areas adjacent to the channel and at the reef. This is a coral reef that is already under tremendous stress from other impacts and is showing the strain; there is little living coral coverage left and all that is there should be strongly protected.
This dredge project is exactly the type of activity that is prohibited by the Florida Keys National Marine Sanctuary. The rules of the sanctuary explicitly prohibit dredging. The additional protection of the U.S. Endangered Species Act designation of corals that will be destroyed add another layer of protection that should strengthen the ability to just say “NO” to a project that will destroy acres of living marine life.