The use of anchors for mooring commercial and recreational boats can cause extensive damage to near-shore marine ecosystems, including coral reefs and sea-bottom habitats, such as sandy, gravel bottoms and rocky reefs. Anchors, and the chains connected to them, sweep the ocean floor, destroying slow-moving animals, benthic (bottom) species and fish nesting sites, resting and feeding grounds. They can crush and destroy coral reefs through sediment disturbance and fragmentation. From an operational perspective, anchoring involves the use of windlasses, anchor chains, anchors, hydraulic systems and other devices that deteriorate and require replacement when used frequently.
Why Should I Care?
While it is possible for sea-bottom habitats, especially coral reefs, to recover from anchor damage, this is a very slow process that can take many decades. In areas of intense anchor damage, it is unlikely that a reef, either rocky or coral, will ever make a full recovery. In these cases, much of the diversity of life – and thus the economic basis of many marine recreation activities – may be lost forever.
Preventing anchor damage requires minimal investment or operational change, but can return significant benefits in terms of increased revenues from tourists who want to see healthy, intact reefs, as well as from operational savings in maintenance and replacement of the different components of the anchoring system. Among the specific impacts of anchoring are:
Fewer Fish: Degraded habitat reduces the number and variety of fish, which are important for both attracting visitors and ensuring the health of the reef.
Fewer Living Corals: Anchors and chains scar coral reefs by breaking and crushing coral colonies and other reef-dwelling organisms, reducing the attractiveness of the area to tourists.
Fewer Rocky Reef Invertebrates: Sea fans, sea cucumbers, starfish, barnacles (and their associated fauna), which require a steady, undisturbed substrate to attach to for their growth and development, can be swept away by the action of an anchor chain.
Destruction of Feeding, Resting And Nesting Sites For Fish And Marine Invertebrates: The sandy ocean bottom is the only habitat for many types of fish, including trigger fish, garden eels, snake eels, batfish, puffer fish and stingrays. Some of these species, in turn, serve as food for attractive large predators such as hammerhead sharks, which may be a draw for visitors to the area. Marine invertebrates, including crabs, shrimp and tube anemones, also thrive only on sandy bottoms, which are often described as underwater deserts.
Cloudy Water: Anchoring can cause an increase in sand and sediment in the water, making once-clear water appear cloudy or murky and preventing corals from getting the sunlight they need to survive. Reduced visibility due to cloudy water negatively affects the quality of the visitor experience in a reef environment.
Destruction of Seagrass Beds: Boats generally swing around in different directions when anchored, and the chains and lines attached to anchors can cause severe damage to seagrass beds, diminishing the quality of the underwater environment and its value as a tourist attraction.
Wear and Tear of Anchoring Systems: Even if well-maintained, the different components of the mooring system on board a boat will deteriorate and need to be replaced sooner if they are used frequently.
What Can I Do?
Use Mooring Buoys: Mooring systems provide permanent lines that allow boaters to fix their position without dropping anchor. An effective mooring program includes the installation of moorings that are suitable for near-shore marine and coral reef areas, use of moorings by all boats, and regular maintenance and correct use of moorings.
Promote and Support Mooring Buoys Installation Programs: Local environmental and merchant marine authorities should install and maintain mooring lines to manage the number of boats at a site at any given moment and to avoid the destruction of oceanbottom ecosystems. If there is such a program already implemented in your area, report any problems the system may have and offer your full support to the initiative.
Change Boating Practices: Small adjustments to standard practice can help save nearshore marine and coral reef ecosystems, for example:
- Correctly use mooring buoys whenever possible. For reasons of safety, always run a check when you tie up to a mooring point (a buoy). Give yourself more room to maneuver by passing a mooring line about half the length of your boat through the eye of the buoy and securing both ends to a cleat on the deck.
- If anchoring is absolutely necessary, make sure your boat is anchored in a designated area, away from important ecosystems and reefs and where it will not be dragged near these areas and accidentally cause damage.
- Consider the use of drift dives instead of anchored dives when no moorings are present.
Educate Customers: Many tourists who rent boats, sailboats, kayaks or canoes (if allowed in an area) have little understanding of how harmful anchors can be to near-shore marine environments and reefs. Educate your customers by:
- Explaining what mooring buoys are and that renters should use them whenever possible.
- Explaining the proper way to anchor, before the renters set out.
- Providing waterproof written reminders of proper anchoring practices on all vessels.
- Explaining the potential impacts of poor anchor use.