Lamarck's sheet coral (Agaricia lamarcki)

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Agaricia lamarcki, showing plate detail
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Lamarck's sheet coral fact file

Lamarck's sheet coral description

KingdomAnimalia
PhylumCnidaria
ClassAnthozoa
OrderScleractinia
FamilyAgariciidae
GenusAgaricia (1)

As its name suggests, Lamarck’s sheet coral (Agaricia lamarcki) forms broad, flat, plate or sheet-like colonies, which are relatively thick and sometimes overlap. Large colonies may even form flattened, whorl-like structures. Lamarck’s sheet coral is normally yellowish-brown or brown, sometimes with greyish tints (3).

As with all corals, the colonies of Lamarck’s sheet coral comprise numerous polyps, anemone-like animals which secrete the coral skeleton. The individual coral skeletons of Lamarck’s sheet coral, known as ‘corallites’, are normally 3.1 to 4.5 millimetres in diameter (3). In this species, the underside of the colony is smooth, while the upper surface bears concentric rows of ridges, with straight or network-like valleys possessing white, star-shaped polyps.

Lamarck’s sheet coral is similar in appearance to the related Graham’s sheet coral (Agaricia grahamae), but has larger corallites and possesses white polyp ‘mouths’, which are absent in Graham’s sheet coral (4) (5).

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Lamarck's sheet coral biology

Like many other corals, Lamarck’s sheet coral is a ‘zooxanthellate’ coral, receiving much of its nutrition as a result of the symbiotic relationship it has with single-celled algae, known as zooxanthellae. These organisms live and photosynthesise within the coral tissues, providing organic nutrients to nourish the polyp, and in return receiving protection and access to sunlight. Corals of this type generally grow faster in clear, shallow waters, with easier access to light (4).

Each polyp of Lamarck’s sheet coral also possesses a ring of stinging tentacles, which are capable of capturing minute zooplankton (4). These tentacles are, however, rarely extended during the day and the majority of the coral’s nutrition is obtained from the zooxanthellae (6).

Corals are capable of reproducing sexually or asexually. Like some other Agaricia species, Lamarck’s sheet coral is thought to be a ‘brooding’ species, whereby fertilisation occurs internally. The larvae develop within the polyp prior to release into the water (7). The age of maturity for most reef-building corals is approximately three to eight years (8).

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Lamarck's sheet coral range

Lamarck’s sheet coral is found in the Caribbean Sea, the Gulf of Mexico and around Florida and the Bahamas (1).

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Lamarck's sheet coral habitat

Lamarck’s sheet coral is normally found on sloping reefs or in channels and deep lagoons. Although it has been recorded at a depth of 76 metres, it is most commonly found at depths of 15 to 25 metres. It may be found at shallower depths in turbid waters (1).

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Lamarck's sheet coral status

Lamarck’s sheet coral is classified as Vulnerable (VU) on the IUCN Red List (1) and is listed on Appendix II of CITES (2).

IUCN Red List species status – Vulnerable

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Lamarck's sheet coral threats

Despite its wide distribution, Lamarck’s sheet coral is relatively rare, and like all corals, it faces numerous threats. Of major concern to corals worldwide is global climate change, which may lead to more severe, frequent storms, ocean acidification and an increase in ocean temperatures, in turn leading to coral ‘bleaching’. Due to their thin tissues, corals are highly sensitive to bleaching events, in which the zooxanthellae are lost, leading to increased disease susceptibility and often death. Coral diseases also affect coral reefs worldwide, and are considered a major contributory factor in reef destruction (1).

Localised human impacts, including fisheries, development, pollution, sedimentation, tourism and coral harvesting, also place additional stress on sensitive coral reef habitats (9). It is estimated that, globally, 20 percent of coral reefs have been destroyed (1).

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Lamarck's sheet coral conservation

Along with all coral species, Lamarck’s sheet coral is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that trade in this coral should be highly regulated. In the United States, Lamarck’s sheet coral is found in many Marine Protected Areas, offering some degree of protection, and harvesting of corals for commercial purposes is illegal in U.S. waters (1).

Further research is required into the biology, population and habitat requirements of Lamarck’s sheet coral and other coral species to determine the most appropriate conservation measures. Techniques for artificial propagation, such as the cryo-preservation (freezing) of gametes, may prove to be an important advance in the protection of coral diversity (1).

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Find out more

To find out more about corals and coral conservation, see:

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

This species information was authored as part of the ARKive and Universities Scheme.
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Glossary

Algae
Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.
Asexually
Of asexual reproduction: reproduction that does not involve the formation of sex cells (‘gametes’). In many species, asexual reproduction can occur by existing cells splitting into two, or part of the organism breaking away and developing into a separate individual. Some animals, including vertebrates, can also develop from unfertilised eggs; this process, known as parthenogenesis, gives rise to offspring that are genetically identical to the parent.
Colony
A group of organisms living together. In organisms such as corals, colonies may be composed of numerous genetically identical modules (also referred to as zooids or ‘individuals’), which are produced by budding and remain physiologically connected.
Fertilisation
The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
Gamete
A reproductive cell which carries the genetic information from an individual, and is capable of fusing with a gamete of the opposite sex to produce a fertilized egg. In animals, male gametes are called sperm and female gametes are called ova.
Larvae
Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Photosynthesis
Metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.
Polyp
Typically sedentary soft-bodied component of Cnidaria, a group of simple aquatic animals including the sea anemones, corals and jellyfish. A polyp comprises a trunk that is fixed at the base, and a mouth that is placed at the opposite end of the trunk and is surrounded by tentacles.
Symbiotic relationship
Relationship in which two organisms form a close association. The term is now usually used only for associations that benefit both organisms (a mutualism).
Turbid
Cloudy or muddy; not clear.
Zooplankton
Tiny aquatic animals that drift with currents or swim weakly in water.
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References

  1. IUCN Red List (August, 2011)
    http://www.iucnredlist.org/
  2. CITES (August, 2011)
    http://www.cites.org/
  3. Marine Species Identification Portal- Lamarck’s sheet coral (Agaricia lamarcki) (February, 2011)
    http://species-identification.org/species.php?species_group=caribbean_diving_guide&id=299
  4. Veron, J.E.N. (2000) Corals of the World. Australian Institute of Marine Science, Townsville, Australia.
  5. Coralpedia - Agaricia grahamae (August, 2011)
    http://coralpedia.bio.warwick.ac.uk/en/corals/agaricia_grahamae.html
  6. Miththapala, S. (2008) Coral Reefs. Coastal Ecosystems Series (Volume 1). Ecosystems and Livelihoods Group Asia, IUCN, Colombo, Sri Lanka. Available at:
    http://data.iucn.org/dbtw-wpd/edocs/2008-012.pdf
  7. Bongaerts, P., Ridgway, T., Sampayo, E.M. and Hoegh-Guldberg, O. (2010) Assessing the 'deep reef refugia' hypothesis: focus on Caribbean reefs. Coral Reefs, 29: 309-327.
  8. Wallace, C. (1999) Staghorn Corals of the World: A Revision of the Genus Acropora. CSIRO Publishing, Victoria.
  9. Carpenter, K.E. et al. (2008) One-third of reef-building corals face elevated extinction risk from climate change and local impacts. Science, 321: 560-563.
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Image credit

Agaricia lamarcki, showing plate detail  
Agaricia lamarcki, showing plate detail

© Charlie Veron / From Coral ID (Veron and Stafford-Smith, 2002)

Charlie (J.E.N) Veron
j.veron@coralreefresearch.com
http://www.coralreefresearch.org/

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