Lophelia pertusa is a species of stony, cold-water coral that creates large deep-sea reefs. These corals form large, bushy colonies of white, pink, or yellowish translucent polyps. Unlike their tropical counterparts, they do not rely on symbiotic algae for energy and thus thrive in the complete darkness of the deep ocean. Recently, molecular evidence led to a proposed name change to Desmophyllum pertusum, but Lophelia pertusa remains widely used, reflecting an ongoing taxonomic debate.
Habitat and Distribution
Lophelia pertusa thrives in specific deep-water environments. It is found at depths between 200 and 1,000 meters, though its full range extends from 80 to over 3,000 meters. The coral requires cold water, living in temperatures between 4 and 12°C. As a suspension feeder, the coral relies on strong currents to deliver food particles like zooplankton.
This species has a wide geographic distribution, with a significant presence in the Northeast Atlantic. Major reef systems are located off the coasts of Norway, Ireland, and Scotland. Its range also extends to the Gulf of Mexico, the Caribbean Sea, and various seamounts and continental shelves across the globe. The reefs develop on hard substrates, which can include old coral rubble or geological features left behind by glaciers.
Deep-Sea Reef Formation
The formation of Lophelia reefs is a slow, cumulative process. The coral captures plankton and organic matter from the water column with its tentacles. The reef’s foundation is built through a cycle of growth where new coral polyps settle and grow upon the calcium carbonate skeletons of previous, deceased generations. Asexual budding, where new polyps emerge from older ones, allows a colony to expand.
This skeletal accumulation happens over immense timescales, with some reef structures dating back thousands of years. Individual coral bushes can live for as long as 1,000 years, contributing to a structure that grows about 1 mm per year. Over millennia, this gradual growth creates a complex, three-dimensional limestone framework. The largest known Lophelia reef, the Røst Reef off Norway’s Lofoten Islands, measures approximately 35 kilometers long.
The Lophelia Reef Ecosystem
The complex structures of Lophelia pertusa are biodiversity hotspots in the deep sea. The reefs’ dense, branching framework provides shelter, feeding grounds, and nursery areas for many marine species. The biological diversity on these reefs can be up to three times higher than on the surrounding soft sediment of the seafloor, making them foundational to the local food web.
Many organisms depend on these reefs. Fish like rockfish, redfish, and grenadiers use the coral for protection from predators and currents. Invertebrates are particularly abundant and include:
- Crabs
- Shrimp
- Squat lobsters
- Sea urchins
- Sponges
Larger animals, like sharks, also frequent these ecosystems for hunting and refuge. The reef structure, both living and dead, sustains this community in the otherwise sparse deep-sea environment.
Threats to Survival
Lophelia reefs face significant threats from human activities. The most direct danger is bottom trawling, a fishing method where heavy nets are dragged across the seafloor. This practice shatters the fragile coral skeletons, flattening the habitat and leaving behind rubble that may take millennia to recover, if at all. A substantial portion of these reefs in Norwegian waters has already been damaged or destroyed by trawling.
Chemical changes in the ocean also pose a risk. Ocean acidification, caused by the absorption of atmospheric carbon dioxide, lowers the pH of seawater. This makes it harder for corals to build their calcium carbonate skeletons and can even cause existing skeletons to dissolve. Other pressures include oil and gas exploration and shifts in ocean currents and temperature from climate change, which could disrupt the coral’s food supply and survivable temperature range.