About Artificial Reef

Artificial reefs have been established for many years in many countries, originated in the 18th century by Japanese fishers who observed and found that a lot of aquatic animals live in the underwater wrecks or dead trees, leading the areas to the high yield of fishery. The first artificial reef began establish in Japan in 1795 by that the fishers experimentally built a large wooden-frame structure with small branches and submerged in the sea at a depth of about 38 meters with sandbags, it is found that the amount of fish caught from this surrounding area was more than that in the shipwreck areas. Hence, many of which were dumped into the sea during that time.  Evolution of artificial reef starts from the use of simple materials obtained from natural products such as woods, bamboos, coconut shells and stones, etc.; other materials include retired automobiles, ships, train bogies, tires; and concrete structures such as sewer drainage, buildings and constructions, roads and bridges, as well as the materials which are specifically designed with different shapes in order to provide more habitats for aquatic life such as Reef Balls and different models of rectangular concrete, etc. . In Florida, USA, the Reef Ball Foundation was established to run business regarding artificial reefs with the purpose of marine resource protection. A hollow-spherical shape of reef balls are designed with different sizes and each cavity inside the ball provides habitats for many fish and other aquatic life. Sherman et al. (2002) studied the influence of the complexity of reef balls on diversity of fish, concluded that the diversity and size of fish are related to the different complexities of artificial reefs. Besides, artificial reefs provide more substrates for coral recruitment and transplantation.     

Figure  Development of artificial reefs

(Source: http://www.reefball.org/index.html)

The different shapes of the artificial reefs are designed in conformity with the desired purposes. Nowadays, concretes are popular materials used to build an artificial reef because of its durability, long-lasting, heaviness, high stability, low-environmental impacts. Concrete is also a good substrate for the attachments of many sessile organisms which serve as food for other fish in the higher tropic levels within a food chain. The examples are shown

 

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Figure  Examples of concrete artificial reefs (Szedlmayer, 1994)

  A factor of material designation for the construction of artificial reef is having gaps or holes that the water can flow through the artificial reefs easily and to allow fish to live within (Szedlmayer, 1994). A form and shape of the materials used in producing artificial reefs are different by countries and purposes; it can be divided as follows:   Artificial reefs for coral reef restoration and recruitment     These artificial reefs are designed for the attachments of sessile organisms such as corals, oysters, algae; benthic organisms, and the juveniles of marine life. Most of the reefs are quite flat that have more recruitment spaces, while some structures are complex. They provide the marine life as a habitat and refuge. Many types of artificial reef are designed in purposes for the increase of area for recruitment and coral reef restoration.     Artificial reef as a fish habitat The artificial reefs which attract various fish are usually built with rather complex structure, providing a cavity in the middle of an artificial reef that allow fish can be resided in   as their habitats and refuges from predators (Lam, 2003). According to the findings of Ogawa (1997) studying the behavior of fish in the artificial reef, it is concluded that the fish living in artificial reef can be categorized into three groups: 1) fish that live in the middle of water column to the surface, i.e., Yellow-fin tuna, Snail-eater pangasius, Trevally, King mackerel sardines and dolphins, are usually found away from the artificial reefs; 2) fish that live near the sea floor and the artificial reefs, i.e., Pink ear emperor, Giant seaperch, True sole; 3) fish that inhabit regularly in the artificial reefs including Cabezon, Rock trout, Eel, Goby usually found close to the artificial reefs (Ogawa, 1997 cited by Poonsin et al, B.E. 2531). 

 

Artificial reef for tourism  In some areas, the artificial reefs are not only advantage in fisheries, but also in tourism because of its uniqueness, for examples, a sinking ship, a sinking airplane, and even the  underwater architecture, etc. Furthermore, if the environment in artificial reef is appropriate for coral larvae recruitment, the abundance and beautifulness of coral reefs may be developed as well as the coral reefs in the nature.    

Figure  Artificial reefs for coral reef restoration and recruitment 

Figure  Artificial reef as a fish habitat

Figure  Artificial reef for tourism