Elkhorn coral
Encyclopedia
Elkhorn coral is considered to be one of the most important reef-building coral
s in the Caribbean
. This species of coral is structurally complex with many large branches. The coral structure closely resembles that of elk antlers. These branches create habitats for many other reef species such as lobster
s, parrot-fish, snapper
s, and other reef fish. Elkhorn coral colonies are incredibly fast growing with an average growth rate of 5 to 10 cm (2 to 3.9 in) per year and can eventually grow up to 3.7 metres (12.1 ft) in diameter. The color of this coral species ranges from brown to a yellowish-brown. This color is a result of the symbiotic zooxanthellae that live inside the tissue of this coral species. Zooxanthellae is a type of algae which photosynthesizes to provide the coral with nutrients. The zooxanthellae are also capable of removing waste products from the coral. Historically, the majority of elkhorn coral reproduction has occurred asexually; this occurs when a branch of the coral breaks off and attaches to the substrate forming a new colony, known as fragmentation. The degree to which local stands reproduce by fragmentation varies across the Caribbean but on average 50% of colonies are the result of fragmentation rather than sexual reproduction. Sexual reproduction occurs once a year in August or September when coral colonies release millions of gamete
s by broadcast spawning.
. Its range reaches as far north as Biscayne National Park
, Florida and as far south as Venezuela. However, it has been suggested that as a result of climate change, the range of elkhorn coral has expanded northward along the Florida Peninsula and into the northern parts of the Gulf of Mexico.
Elkhorn coral are found primarily in shallow waters with temperatures between 26 to 30 °C (78.8 to 86 F), and with significant water movement. They are one of the most abundant species in waters ranging from 1 to 5 m (3.3 to 16.4 ft) deep, and a few colonies have been reported from waters as deep as 20 metres (65.6 ft) (e.g. Navassa Island
).
Elkhorn coral was once one of the most abundant species of coral in the Caribbean
and the Florida Keys
. Since 1980 it has been estimated that 90-95% of elkhorn coral has been lost. Threats to elkhorn coral include disease, coral bleaching
, predation, climate change, storm damage, and human activity. All of these factors have created a synergistic effect that greatly diminishes the survival and reproductive success of elkhorn coral. Natural recovery of coral is a slow process and may never occur with this species because there are so many inhibitors to its survival.
Diseases that affect elkhorn coral include white pox disease
, white band disease
, and black band disease
. White pox disease is a disease that only affects elkhorn coral. It is caused by a fecal enterobacterium, Serratia marcescens
. The disease is very contagious and commonly moves from one colony to its nearest neighbor. White pox creates white lesions on the coral skeleton and results in an average tissue loss of 2.5 square centimetre per day but can cause as much tissue loss as 10.5 square centimetre per day. White band disease and black band disease have also greatly reduced the abundance of elkhorn coral. Diseases are one of the major causes of coral mortality, however, they are not well studied or understood.
Predators of Elkhorn coral include coral eating snails (Coralliophila abbreviata), polychaetes such as the bearded fireworm
and damselfish
. Predation by these organisms reduces the corals growth and ability to reproduce. Predation can eventually lead to the death of the coral colony.
and the Virgin Islands
but all have had limited success.
Attempts are also being made to conserve the coral by culturing coral fragments. The Florida Keys National Marine Sanctuary, the National Oceanographic and Atmospheric Administration, and Mote Marine Laboratory
all are having limited success with coral nurseries in the Florida Keys and Puerto Rico.
The National Oceangraphic and Atmospheric Administration (NOAA) has developed and tested several ecological methods to restore this coral. These methods include removing coral predators and reintroducing herbivores to the ecosystems to feed on harmful algae that grows on the coral.
In 2004, the Center for Biological Diversity
requested the National Marine Fisheries Service
(NMFS) placed elkhorn coral on the endangered species list. In 2005, NMFS decided that elkhorn coral qualified as an endangered species under the Endangered Species Act of 1973. On May 4, 2006 Elkhorn coral and Staghorn coral
(A. cervicornis) were officially placed on the Endangered Species List.
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
s in the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
. This species of coral is structurally complex with many large branches. The coral structure closely resembles that of elk antlers. These branches create habitats for many other reef species such as lobster
Lobster
Clawed lobsters comprise a family of large marine crustaceans. Highly prized as seafood, lobsters are economically important, and are often one of the most profitable commodities in coastal areas they populate.Though several groups of crustaceans are known as lobsters, the clawed lobsters are most...
s, parrot-fish, snapper
Lutjanidae
Snappers are a family of perciform fish, mainly marine but with some members inhabiting estuaries, feeding in freshwater. Some are important food fish. One of the best known is the red snapper....
s, and other reef fish. Elkhorn coral colonies are incredibly fast growing with an average growth rate of 5 to 10 cm (2 to 3.9 in) per year and can eventually grow up to 3.7 metres (12.1 ft) in diameter. The color of this coral species ranges from brown to a yellowish-brown. This color is a result of the symbiotic zooxanthellae that live inside the tissue of this coral species. Zooxanthellae is a type of algae which photosynthesizes to provide the coral with nutrients. The zooxanthellae are also capable of removing waste products from the coral. Historically, the majority of elkhorn coral reproduction has occurred asexually; this occurs when a branch of the coral breaks off and attaches to the substrate forming a new colony, known as fragmentation. The degree to which local stands reproduce by fragmentation varies across the Caribbean but on average 50% of colonies are the result of fragmentation rather than sexual reproduction. Sexual reproduction occurs once a year in August or September when coral colonies release millions of gamete
Gamete
A gamete is a cell that fuses with another cell during fertilization in organisms that reproduce sexually...
s by broadcast spawning.
Distribution
Elkhorn coral exist in the Caribbean, the Bahamas, and Florida KeysFlorida Keys
The Florida Keys are a coral archipelago in southeast United States. They begin at the southeastern tip of the Florida peninsula, about south of Miami, and extend in a gentle arc south-southwest and then westward to Key West, the westernmost of the inhabited islands, and on to the uninhabited Dry...
. Its range reaches as far north as Biscayne National Park
Biscayne National Park
Biscayne National Park is a U.S. National Park located in southern Florida, due east of Homestead. The park preserves Biscayne Bay, one of the top scuba diving areas in the United States. Ninety-five percent of the park is water. In addition, the shore of the bay is the location of an extensive...
, Florida and as far south as Venezuela. However, it has been suggested that as a result of climate change, the range of elkhorn coral has expanded northward along the Florida Peninsula and into the northern parts of the Gulf of Mexico.
Elkhorn coral are found primarily in shallow waters with temperatures between 26 to 30 °C (78.8 to 86 F), and with significant water movement. They are one of the most abundant species in waters ranging from 1 to 5 m (3.3 to 16.4 ft) deep, and a few colonies have been reported from waters as deep as 20 metres (65.6 ft) (e.g. Navassa Island
Navassa Island
Navassa Island is a small, uninhabited island in the Caribbean Sea, claimed as an unorganized unincorporated territory of the United States, which administers it through the U.S. Fish and Wildlife Service. Haiti, which claims to have had sovereignty over Navassa since 1801, also claims the island...
).
Threats
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
and the Florida Keys
Florida Keys
The Florida Keys are a coral archipelago in southeast United States. They begin at the southeastern tip of the Florida peninsula, about south of Miami, and extend in a gentle arc south-southwest and then westward to Key West, the westernmost of the inhabited islands, and on to the uninhabited Dry...
. Since 1980 it has been estimated that 90-95% of elkhorn coral has been lost. Threats to elkhorn coral include disease, coral bleaching
Coral bleaching
Coral bleaching is the loss of intracellular endosymbionts through either expulsion or loss of algal pigmentation.The corals that form the structure of the great reef ecosystems of tropical seas depend upon a symbiotic relationship with unicellular flagellate protozoa, called zooxanthellae, that...
, predation, climate change, storm damage, and human activity. All of these factors have created a synergistic effect that greatly diminishes the survival and reproductive success of elkhorn coral. Natural recovery of coral is a slow process and may never occur with this species because there are so many inhibitors to its survival.
Diseases that affect elkhorn coral include white pox disease
White pox disease
White pox disease , first noted in 1996 on coral reefs near the Florida keys, is a coral disease affecting Elkhorn coral throughout the Caribbean. It causes irregular white patches or blotches on the coral that result from the loss of coral tissue...
, white band disease
White band disease
White band disease is characterized by complete coral tissue degradation of Caribbean acroporid corals. Two species are affected, Acropora palmata and A. cervicornis . The disease exhibits a sharp demarcation between apparently healthy coral tissue and exposed coral skeleton...
, and black band disease
Black band disease
Black band disease is characterized by complete coral tissue degradation due to a pathogenic microbial consortium that appears as a dark red or black migrating microbial mat. The mat is present between apparently healthy coral tissue and freshly exposed coral skeleton.-Appearance:Black Band disease...
. White pox disease is a disease that only affects elkhorn coral. It is caused by a fecal enterobacterium, Serratia marcescens
Serratia marcescens
Serratia marcescens is a species of Gram-negative, rod-shaped bacterium in the family Enterobacteriaceae. A human pathogen, S. marcescens is involved in nosocomial infections, particularly catheter-associated bacteremia, urinary tract infections and wound infections, and is responsible for 1.4% of...
. The disease is very contagious and commonly moves from one colony to its nearest neighbor. White pox creates white lesions on the coral skeleton and results in an average tissue loss of 2.5 square centimetre per day but can cause as much tissue loss as 10.5 square centimetre per day. White band disease and black band disease have also greatly reduced the abundance of elkhorn coral. Diseases are one of the major causes of coral mortality, however, they are not well studied or understood.
Predators of Elkhorn coral include coral eating snails (Coralliophila abbreviata), polychaetes such as the bearded fireworm
Bearded fireworm
The bearded fireworm, Hermodice carunculata, is a type of marine bristleworm.-Appearance:Bearded fireworms are usually between 5–10 centimetres in length, but can reach up to 35 centimetres . They are endowed with a group of poisonous white bristles on each side, which are flared out when...
and damselfish
Damselfish
Damselfish comprise the family Pomacentridae except those of the genera Amphiprion and Premnas. They can grow up to long. While most are marine, a few species inhabit the lower stretches of rivers in freshwater. Damselfish usually have bright colors. in tropical coral reefs, and many of those are...
. Predation by these organisms reduces the corals growth and ability to reproduce. Predation can eventually lead to the death of the coral colony.
Conservation
There have been several efforts to conserve the Elkhorn coral which have had mixed results. The Florida Keys National Marine Sanctuary has served as a protected region for the area’s coral species. The Florida Keys National Marine Sanctuary has also developed plans for the protection and restoration of elkhorn coral. Restoration efforts have included attempts to re-attach coral fragments that were broken off during hurricanes or by ships. Attempts to re-attach coral fragments have also occurred in Puerto RicoPuerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...
and the Virgin Islands
Virgin Islands
The Virgin Islands are the western island group of the Leeward Islands, which are the northern part of the Lesser Antilles, which form the border between the Caribbean Sea and the Atlantic Ocean...
but all have had limited success.
Attempts are also being made to conserve the coral by culturing coral fragments. The Florida Keys National Marine Sanctuary, the National Oceanographic and Atmospheric Administration, and Mote Marine Laboratory
Mote Marine Laboratory
Mote Marine Laboratory is an independent not-for-profit marine research organization based on City Island in Sarasota, FL. The laboratory aims to advance the science of the sea, both through its marine and estuarine research labs and through the public Mote Aquarium and its affiliated educational...
all are having limited success with coral nurseries in the Florida Keys and Puerto Rico.
The National Oceangraphic and Atmospheric Administration (NOAA) has developed and tested several ecological methods to restore this coral. These methods include removing coral predators and reintroducing herbivores to the ecosystems to feed on harmful algae that grows on the coral.
In 2004, the Center for Biological Diversity
Center for Biological Diversity
The Center for Biological Diversity based in Tucson, Arizona, is a nonprofit membership organization with approximately 220,000 members and online activists, known for its work protecting endangered species through legal action and scientific petitions...
requested the National Marine Fisheries Service
National Marine Fisheries Service
The National Marine Fisheries Service is a United States federal agency. A division of the National Oceanic and Atmospheric Administration and the Department of Commerce, NMFS is responsible for the stewardship and management of the nation's living marine resources and their habitat within the...
(NMFS) placed elkhorn coral on the endangered species list. In 2005, NMFS decided that elkhorn coral qualified as an endangered species under the Endangered Species Act of 1973. On May 4, 2006 Elkhorn coral and Staghorn coral
Staghorn coral
The Staghorn coral is a branching coral with cylindrical branches ranging from a few centimetres to over two metres in length and height. It occurs in back reef and fore reef environments from 0 to 30 m depth. The upper limit is defined by wave forces, and the lower limit is controlled by...
(A. cervicornis) were officially placed on the Endangered Species List.