The legs and transoms of many of the platforms are covered with Live rock organisms. Live rock is a foundation of calcium carbonate material that maintains living organisms such as a sea anemone, sponge, tube worm, bryzoan, and marine algae.
A multitude of invertebrates colonize the underwater structure. The type of live rock that prevails depends on a number of factors. Environmental conditions such as turbidity at location of the platform influences the type of species that effectively colonize the substrate. Gallaway and Lewbell (1982) observed a distinct change in the sessile communities across the Louisiana shelf. The platforms in the turbid coastal region were dominated by barnacles and the mid-shelf platforms were inhabited by a Caribbean fauna mix and the deep, blue-water platforms were dominated by Caribbean species.
Some species are more successful at different depths. The time the platform has been in the water also influences the type of organisms that settle on the substrate. For example, marine algae and barnacles settle on the platforms almost immediately after installation, and then sea anemones, tube worms, and sponges find their way to the platforms. After 12 or so years, coral begin to attach to some blue water platforms.
The platforms support several tons of Live rock and every year over 100 platforms are removed. Although these organisms are protected by harvest regulations, the Live rock you see on the platforms are not protected because the foundation the animals do not fall under the management unit outlined in the Gulf of Mexico FMP (Amendment 2) for Coral and Coral Reefs.
Live rock is both the living organism and the limestone base it is attached to. While the living organisms are thriving on the platforms, they are not protected because they do not fall under this definition found in the Coral FMP
hard substrate that forms the base of the live rock is usually calcareous
material such as limestone rock, fossil and dead corals. Individual
mollusk shells (scallops, clams, oysters, etc.) are not intended to be
included in the definition as the hard substrate in live rock". Amendment
2 to the FMP for Coral and Coral Reefs of the Gulf of Mexico July 1994
Mollusk are common inhabitants on offshore platforms, however, they are most abundant on the top 3 m near the surface. Below that area, they become less numerous and Live rock organisms settle on calcareous remains of barnacles, algae, sponge, and tunicates (other live rock organisms). In the two pictures below, you can see how mollusk dominate the surface area (right) and below that zone, sponge, marine algae, bryozoans, and other live rock organisms dominate.
Also see.......Medical applications of Live rock
Essential Fish Habitat | Endangered Species Habitat | Federally Managed Species | Coral Habitat | Live Rock | Schooling Fish | Attraction vs. Production