How Wrecks Help the Reefs and Reefs Help the Wrecks

The Importance of Wrecks as Artifical Reefs

Wreck Diving on an artifical reef.
Over time, wrecks become covered with coral and sponges, attracting fish, eels, and even sharks!. © Getty Images

From experiencing history first-hand to challenging yourself with an advanced dive environment, there are almost as many reasons to wreck dive as there are wreck divers. Whatever your reasons for loving wreck diving, the wealth of aquatic life found on shipwrecks is likely to be somewhere on your list. Submerged wrecks act as artificial reefs, providing an attachment point for corals, sponges, and other creatures, which attract a variety of fish and marine animals to areas normally devoid of life.

 

Artificial Reefs Are Not a New Concept

Humans have been using ships and other objects for centuries (possibly thousands of years) to create or enhance fish habitats in areas of low fish abundance.  This practice continues today as ships, planes, and even subways cars are cleaned, stipped down, and submerged to attract marine life to a dive site or to provide fish habitats and coral subtrates in regions suffering from dimishing fish and coral populations.  

Wrecks Often Attract More Fish Than Natural Reefs

Wrecks and other artifical reefs make excellent dive sites because artifical reefs are known to have both higher numbers and a greater diversity of marine life than nearby natural reefs. When you visit a shipwreck, you will often see not only a great deal of marine life, but a great deal of marine life concentrated into a relatively small area. For this reason, you'll often see more creatures on a single wreck than you would on natural reef in the same area.

 

Watching a Reef Take Form

If you have the opportunity to dive a purposefully submerged wreck immediately after its sinking and visit it periodically afterwards, its possible to watch the process of marine life colonization. Watching how a wreck changes as marine life claims it is absolutely fascinating.

 

First, algae and other fixed life forms such as barnacles and bryzoans settle on the wreck. This creates a habitat, and fish are attracted to the wreck. 

Over time, other fixed marine life including sponges, soft, and hard corals grow on the wreck, creating more habitats and attracing even more marine life. 

As wrecks are three-dimensional structures, they offer a variety of habitats from exposed surfaces to holds and cave-like shelters. Its common to find eels, lobsters, fish, sharks, and rays all clustered around a wreck in an otherwise empty area. 

Artifical Reefs Vary With Depth and Location

Tthe reefs that form on wrecks in can be quite different depending on depth and location.

A great example of this is at Chuuk (Truk Lagoon) in the Federated States of Micronesia, a world renowned wreck diving destination. The wrecks have been there for over 70 years, sunk during World War II.  Some have so much marine life covering them you can easily forget you are diving a wreck, and others in deeper water are still relatively clean. 

The wrecks in Chuuk Lagoon are historical, but they are also world-class artifical reefs. They are covered in brightly coloured soft and hard corals, huge gorgonian fan corals, sea whips, sponges, ascidians, anemones, and different types of algae.

Fish and other critters live around them, including nudibranchs, flatworms, all kinds of different shrimp, shells. They attract the pelagics divers love to see, like different types of trevally (or jacks), barracuda, and sometimes even grey reef sharks or eagle and manta rays. Turtles love the wrecks too and it is not uncommon to see them around the wrecks and even sleeping inside the wrecks. One time I was lucky enough to be buzzed by dolphins!  So even if you don’t want to go inside wrecks, there is so much life to see, aside from the rust, which many of us love too!

Wrecks Are Always Changing

Wrecks can become covered with marine life, growing as an artificial reef, and they can also decompose and fall apart. These processes happen over an extended period of time, but environmental factors may cause more aburpt changes.

When a storm or other weather event affects the conditions around the wreck, it may shift position or even break apart. Marine life covering the wreck may be damaged or dislodged, and at first you will notice scars and empty spaces on the wreck. Over time, these bare areas will be covered back up with new, and sometimes different creatures as marine life reclaims the wreck. One day you may drop down on your favorite wreck and find that everything has changed!

More Wreck Diving Articles:

Three Types of Wreck Diving: Which Is For You?

The Hazards and Dangers of Wreck Diving

Torben Lonne's Top Ten Wreck Dives

Studying Artifical Wrecks for Science

Clearly wrecks make great artificial reefs and attractive dive sites, but they can also be useful for marine biologists studying the process of colonization. Marine biologists use wrecks and artificial reefs to observe the rate at which marine life grows on or populates the wreck, and the changes that occur over time. This helps them to understand different ecological processes that occur on natural reefs, and how natural reefs may be able to heal themselves after they have been damaged in some way, such as by a storm.

Marine Life May Help to Preserve Wrecks

The marine life we enjoy seeing on wrecks may actually help to preserve them. The creatures we see covering our favorite wrecks can help to slow corrosion and other decay processess, whiile stablizing the wreck and holding it together. If we protect the marine life growing on wrecks, the wreck will last longer! 

The Take Home Message About Wrecks as Artifical Reefs

Wrecks are interesting in their own right, and also serve as artifical reefs. This not only attracts divers, leading to a call for preservation of the wrecks as dive sites, but it helps to repopulate areas with sparse fish or coral populations. Scientists study wrecks to learn about marine life colonization and reef recovery after catastrophic events.  The marine creatures covering a wreck may also help to stabilize it and slow decay.

The marine ecosystem is complex and interconnected, and it rapidly assimilates wrecks and makes them part of the environment. Watching this process occur is one of the many joys of wreck diving. 

Jo Edney is a dive researcher, currently focusing on wreck diving.