"Live rock" is rock from the ocean that has been introduced into a saltwater aquarium, which confers to the closed marine system multiple benefits desired by the salt water aquarium hobbyist. The name sometimes leads to misunderstandings, as "live rock" itself is not actually alive, but is made simply from the calcium carbonate skeletons of long dead corals, or other calcareous organisms, which in the ocean form the majority of coral reefs. When taken from the ocean it is usually encrusted with Coralline algae and inhabited by a multitude of marine organisms. The many forms of micro and macroscopic marine life that live on and inside of the rock, and which acts as an ideal habitat, give it the name "live rock."

Origin

Live rock is harvested for use in the aquarium trade from collections in the wild near reefs, where parts may become detached from the main body of coral by storms. Or it may be from small coralline rocks which are "seeded" by an aquaculturalist in warm ocean water, to be harvested later. Live rock can also be seeded by adding base rock to an active reef aquarium that already has live rock. Live rock harbors a wide variety of corals, algae, sponges, and other invertebrates, when they are collected. Corals added to the aquarium later will often be attached to rock.

Types of Live Rock

There are many different types of live rock, and each is named after the area from which it originated. A large amount of live rock comes from the Southern Pacific region, in areas such as Fiji and Tonga. Each has its own distinct qualities that make it preferable to reef aquarists. For instance, live rock from the Fiji region is often porous and large, and rock from the Tonga region is often dense and elongated. Some of the more popular types of live rock today include Walt Smith, Marshall Island and Kaelini.

Purpose

For the aquarium trade this rock is highly valued not only for the diversity of life it can bring to the closed marine environment, but its function as a superior biological filter that hosts both aerobic and anaerobic nitrifying bacteria required for the nitrogen cycle that processes waste. Live rock becomes the main biological nitrification base or biological filter of a saltwater aquarium. Additionally, "live rocks" have a stablizing effect on the water chemistry, in particular on helping to maintain constant pH by release of calcium. Lastly, live rock, especially when encrusted with multiple colors of coralline algae, becomes a major decorative element of the aquarium and provides shelter for the inhabitants. It's often used to build caves, arches, overhangs, or other structures in the tank, an art known as aquascaping.

In J. Charles Delbeek's article "Your First Reef Aquarium, he states,

The use of live rock immediately introduces into the aquarium numerous algae, bacteria and small invertebrates all of which contribute to the overall quality of the aquarium water. Live rock has just as much, if not more, surface area for bacteria than a trickle filter. Since live rock in the aquarium contains various types of bacteria, algae and corals, waste products such as ammonia, nitrate and phosphate can have a number of fates. Ammonia, nitrate and phosphate are readily assimilated by algae and photosynthetic corals growing on and in the rock. Ammonia can also be quickly converted into nitrate by the bacteria on and in the rock. This nitrate can be either absorbed by the algae and corals, or it can be denitrified by bacteria in close proximity to the nitrate-producing bacteria.

Tonga, Marshall and Cook Islands ban

As of August 4, 2008 CITIES (Convention on International Trade in Endangered Species) has banned the collection of live rock from the kingdom of Tonga, the Marshall Islands and the Cook Islands. This is due to the over collecting of rock in these areas. article

• About Live Rock and its purpose

References