Marine Biology Negative Effects of Artificial Reefs

¶ … Negative Effects of Artificial Reefs

Artificial reefs are man-made habitats that are created from many different materials to build new marine life communities (Rodriguez, 2004). For many years, fish and shellfish habitats have been damaged or wiped out by the development of new coastal areas, accidents, and major storms. As a result, there has been a decline in different marine life populations. Artificial reefs provide food, shelter, protection, and spawning areas for many species of fish and other marine organisms. However, artificial reefs are not just used for fish. They are also created to provide areas for scuba divers and anglers to use, reducing the human pressures that natural reefs bear on a regular basis.

Natural reefs can be looked at as the rain forests of the seafloor, supporting a broad diversity of species (Bourjaily, 2000). Like many other things found in nature, they often take centuries to mature. Due to pollution, temperature change, dredging, ship groundings, commercial fishing, and recreational diving, the reefs are in danger.

Artificial reefs have been created as a solution to this problem (Bourjaily, 2000). Artificial reefs are not a new concept, but only recently have they become a major aspect the marine environment. The first artificial reefs were made from tires, appliances, sunken ships, junked cars, culverts and concrete rubble. For this reason, they actually do more harm than good.

Artificial reefs come in many forms -- while some are created thoughtfully and purposefully, others are just a cheap way to throw out trash (Goldschmid, 1998). Although most artificial reefs provide some habitat for certain kinds of marine life, these are not always positive areas. Artificial reefs can cause a great deal of damage to natural habitats during their construction and can displace natural species and habitats. They also have a tendency to concentrate fish unnaturally, making them more vulnerable to over fishing. In some cases, they bring toxins and other pollutants into the ocean.

Many artificial reefs are just different materials tossed into the sea: wrecked cars, planes, boats, building materials and tires. Perhaps a better name for artificial reefs would be a pile of junk. Underwater, while this junk may provide some shelter for fish, it also corrodes, breaks, rusts, decomposes and leaches toxic chemicals into the water. Corals may grow very slowly on them, if at all. Normally the growth is just a bunch of weedy organisms. In the long-term, these artificial reefs are destroyed by wave forces and then become dangerous projectiles in storms.

According to Bourjaily (2004): "Tires wash ashore. Appliances, cars and ships leak harmful chemicals. Heavy objects damage natural reefs as currents toss and turn them over the seafloor. Today, only concrete and heavy-gauge steel are allowed in most U.S. waters. Deliberately sunk ships must be thoroughly cleaned before they are left to drown.

Structures are now being designed specially as artificial reefs, and stable, non-toxic concrete is the material of choice."

While artificial reefs are no longer major pollutants and no longer wash up on shore, it is unclear if reefs increase fish populations or make them easier prey for anglers. According to marine officials, artificial reefs provide more habitat and increase fish populations. They also say that angling harvests are indeed on the rise, effectively canceling the population growth. "In some cases fish seem to prefer artificial reefs to lower-relief natural reefs nearby, but they're moving into a baited trap, because anglers know where the artificial reefs are," says Jon Dodril of the Florida Division of Marine Fisheries (Bourjaily, 2000). Building mitigating artificial reefs when real reefs are damaged fails to address problems of pollution, nutrient runoff and over-exploitation of the oceans, he also argues.

One of the biggest problems with artificial reefs is the impact on the environment.

One key concern in this area is coastal erosion. Insufficiently weighted materials that end up miles away from the reef site by strong winter storm (such as tires, etc.) can damage sedentary organisms of natural reef sites and destroy the nets of commercial fisherman's bottom trawl (Goldschmid, 1998).

Environmentalists say artificial reefs may be harming dwindling populations of fish (Dixie Divers, 2004). Rather than helping fish stocks recover by creating more habitat, they simply draw the remaining fish to fishermen's hooks. "Do they only attract fish so that fishermen can take more fish?" asked David White, southeast regional director of the Ocean Conservancy. "If they're just giant fish attractors, they're just leading to greater depletion of fish."

Artificial reefs alter ocean habitats. An artificial reef transforms a sandy or muddy bottom habitat, which supports worms, mollusks and other marine life, into a reef ecosystem (Dixie divers, 2004). Many reefs are being created without considering the consequences of changing ocean ecosystems. "They can be dangerous," said Cufone, of the Ocean Conservancy. "We're not certain of the impacts." John McManus, director of the National Center for Caribbean Coral Reef Research at the University of Miami, said artificial reefs threaten depleted fish populations. Attracting fish from coral outcroppings that fishermen may not know about, these reefs create a concentrated population of fish exactly where the hooks will be.