1 / 30

Branching Corals

Branching Corals. M.L. Anderson, 2009. Corals. Corals can be considered either hard or soft depending on their consistency and the nature of their skeletons. Hard corals are reef building corals that secrete a hard external limestone skeleton.

johana
Télécharger la présentation

Branching Corals

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Branching Corals • M.L. Anderson, 2009

  2. Corals • Corals can be considered either hard or soft depending on their consistency and the nature of their skeletons. • Hard corals are reef building corals that secrete a hard external limestone skeleton. • After the coral polyp dies, the skeleton remains and becomes the foundation for a new generation. • Hard corals grow in three basic forms: • Massive (brain coral) • Branching (Elkhorn and Staghorn coral) and • Plate (leaf coral).

  3. Staghorn CoralTaxonomy • Name: Staghorn Coral (Acroporacervicornis) • Kingdom: Animalia • Phylum: Cnidaria • Class: Anthozoa • Order: Scleractinia • Family: Acroporidae • Genus: Acropora • Species: cervicornis

  4. Staghorn Coral - Description • A branching coral with cylinder like branches that range from a few centimeters to over 6.5 feet in length • Brown to yellow-brown with a pale tip on the end of each branch • Exhibits the fastest growth of all known W. Atlantic coral • Increasing in length by 4-8 inches per year.

  5. Staghorn Coral - Description • Reproduction for staghorn coral is: • Asexual fragmentation-new colonies form when branches break off a colony and reattach to the substrate. • Sexual reproduction-occurs when broadcast spawning of gametes into the water column once each year in August or September. Individual colonies are both male and female and release millions of gametes.

  6. Staghorn CoralImportance of Species • One of the three most important Caribbean corals in terms of its contribution to reef growth and fish habitat • Exhibits the fastest growth of all known W. Atlantic corals • Provides habitat for reef fish and invertebrates • Offers shoreline protection from storms

  7. Staghorn Coral - Map • Coast of Florida • Fla. Keys • Puerto Rico & U.S. Virgin Islands • The Bahamas • The Caribbean islands • Venezuela • Southern & SW Gulf of Mexico

  8. Staghorn Coral - Habitat • Found in: • Back reef and fore reef environments from 0-98 feet deep • The upper limit is: • Defined by wave forces • The lower limit is: • Controlled by suspended sediments and light availability

  9. Staghorn Coral - Habitat • Fore reef zones at intermediate depths of 16-82 feet were formerly dominated by extensive single species stands of staghorn coral until the mid 1980s

  10. Staghorn Coral - Threats • Listed as “threatened” in 2005. • Region-wide mortality for staghorn coral has been caused by disease outbreaks, which are mainly of white band disease. • More localized losses have been caused by: • Hurricanes • Increased predation • Bleaching • Algae Overgrowth • Human impacts • Other factors. • This species is also particularly susceptible to damage from sedimentation and is sensitive to temperature and salinity variation.

  11. Staghorn Coral: Threats • The dominant mode of reproduction is asexual fragmentation which allows rapid population recovery from physical disturbances such as storms. • However, this mode of reproduction makes recovery from disease or bleaching episodes (in which entire colonies or even entire stands are killed) very difficult. • The large role of asexual reproduction for this species also decreases the genetic diversity in the populations. • Scientists are concerned for this species because of its species recruitment and genetic diversity.

  12. Staghorn Coral - Conservation • Prohibited to remove this species from reef environments • Illegal to damage, collect or sell this species within state, territorial and federal waters. • Florida Keys National Marine Sanctuary (FKNMS) have developed a plan that includes: • Protective activities • Zone & Channel markings • Restoration activities

  13. Staghorn Coral - Conservation • Restoration activities include: • Re-attaching coral fragments generated by ship groundings and hurricane events • Mixed results • Done in: Puerto Rico & U.S. Virgin Islands • Attempts to culture and settle coral larvae with very limited success • March 4, 2009-Center for Biological Diversity petitioned staghorn coral under the Endangered Species Act (ESA). • June 23, 2004-Began investigation • March 18, 2005-Listed as threatened

  14. Staghorn Coral - Laws • The United States Coral Reef Task Force was established in 1998 by Presidential Executive Order 13089 to coordinate and strengthen efforts for protecting coral reef ecosystems. • The Task Force is co-chaired by the Departments of Commerce and Interior, which includes leaders of 12 federal agencies, 7 U.S. states and territories, and 3 freely associated states. • In 2002, the Task Force adopted a resolution calling for the development of local action strategies, which are locally-driven plans for collaborative and cooperative action among federal, state, territory, and non-governmental partners to reduce key threats on valuable coral reef resources. • Three Local Action Strategies have been developed within the range of staghorn coral for Florida, Puerto Rico, and the U.S. Virgin Islands. They are now underway and will be implemented over a three-year period.

  15. Staghorn CoralWhat it is used for? • Nothing for tangible or man-made reasons. Coral reefs offer: • Scuba diving • Fishing • Boating • Other activities

  16. Elkhorn coral • Elkhorn coral grows very slowly but can grow to be one of the largest corals in a coral reef. • It is very rare on shallow reefs and is more common deeper in the ocean. • It is very susceptible to disease & breakage during storms & climate change.

  17. What is Elkhorn Coral? • Elkhorn coral is a large, branching coral with thick and sturdy antler-like branches. • The dominant mode of reproduction for Elkhorn coral is asexual, with new colonies forming when branches break off of a colony and reattach to the substrate.

  18. Building of Colonies • The coral larvae live in the plankton for several days until finding a suitable area to settle, but very few larvae survive to settle and metamorphose into new colonies. • Colonies are fast growing: branches increase in length by 2-4 inches (5-10 cm) per year, with colonies reaching their maximum size in approximately 10-12 years. Elkhorn Coral grows upwards to get closer to the sun.

  19. Elkhorn Coral Habitat • Elkhorn coral was formerly the dominant species in shallow water (3 ft-16 ft (1-5 m) deep) throughout the Caribbean and on the Florida Reef Tract, forming extensive, densely aggregated thickets in areas of heavy surf.

  20. Elkhorn Coral Habitats • Elkhorn coral is found on coral reefs in southern Florida, the Bahamas, and throughout the Caribbean. • Its northern limit is Biscayne National Park, Florida, and it extends south to Venezuela.

  21. Florida Reef Tract for Elkhorn and Staghorn Coral

  22. Threats to the Elkhorn Coral • Since 1980, populations of Elkhorn coral have collapsed from disease outbreaks with losses compounded locally by hurricanes, increased predation, bleaching, elevated temperatures, and other factors. • This species is also particularly susceptible to damage from sedimentation.

  23. Coral Bleaching • The primary cause of coral bleaching is high water temperature. Temperature increases of only 1.5–2°C lasting for six to eight weeks are enough to trigger bleaching. When high temperatures persist for more than eight weeks, corals begin to die. • Elevated water temperature is of greater concern as it can affect reefs at regional to global scales. When bleaching occurs at these large spatial scales, it is a mass bleaching event.  Bleached elkhorn coral near St. Croix, USVI, in October 2005. (Source: NOAA Center for Coastal Monitoring and Assessment)

  24. What is Coral Bleaching? • Coral bleaching occurs when the coral host expels its zooxanthellae (microscopic algae). • Photosynthetic pigments of the zooxanthellae give corals much of their color. • Therefore without the zooxanthellae, the tissue of the coral animal appears transparent and the coral’s bright white skeleton is revealed. 

  25. Coral Bleaching Corals begin to starve once they become bleached. If conditions return to normal, corals can regain their zooxanthellae, return to normal color and survive. This stress, however, is likely to cause decreased coral growth and reproduction, and increased susceptibility to disease.

  26. Loss of Elkhorn Coral • In areas where loss has been quantified, estimates are in the range of 90-95% reduction in abundance since 1980. Additional drastic reductions (75-90%) were recently observed in some areas such as the Florida Keys in 1998 due to bleaching and hurricane damage.

  27. Elkhorn Coral Destroyed by Hurricanes in the Florida Keys

  28. Conservation Efforts • Florida Keys National Marine Sanctuary (FKNMS), the largest coral reef management entity in the region, has developed a management plan for the Sanctuary's corals that includes protective activities, such as zoning, channel markings, and restoration efforts.

  29. Conservation Efforts • Restoration activities have included efforts to re-attach broken fragments of Elkhorn coral caused by ship groundings and hurricane events; these efforts have had mixed success. • Other restoration efforts have included attempts to culture and settle coral larvae with limited success.

  30. Citations • http://away.com/images/features/snorkeling-elkhorn-coral.jpg • http://www.nmfs.noaa.gov/pr/species/invertebrates/elkhorncoral.htm • http://www.biologicaldiversity.org/species/invertebrates/elkhorn_coral/ • http://www.gbrmpa.gov.au/corp_site/key_issues/climate_change/climate_change_and_the_great_barrier_reef/what_is_coral_bleaching • http://aqua-ca.com/coralreef.aspx • www.biologicaldiversity.org/.../coral_image/ • http://www.nmfs.noaa.gov/pr/pdfs/species/acropora_factsheet.pdf • http://www.flmnh.ufl.edu/fish/southflorida/coral/Profiles.html • http://www.biologicaldiversity.org/species/invertebrates/staghorn_coral/ • http://www.peteducation.com/article.cfm?c=16+1928&aid=2353

More Related