BankReefs

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Bank Reefs

Formation

These reefs are built upward from the seafloor by non-photosynthetic coral. A single species often builds these deep-water reefs up.[1] Photosynthesis is not typically the primary energy source for this system as they exist at depths to which sunlight cannot consistently penetrate effectively. [1]

Morphology and Ecology

Bank reefs are characterized by coral formations in linear or semi-circular clustered patterns that are often larger than similar coral formations such as patch reefs. [2] These coral formation typically consists of three regions that are distinct in location and the type of coral from which they are formed. The Reef Flat occupies the inshore side of the bank reef. This consists of broken coral skeletons and coralline algae to the exclusion of most other organisms due to the inhospitable heavy surf that often characterizes this area. [2] The next adjacent section is the Spur and groove patterned region. Spurs are low ridges of coral. These areas are dominated by fire corals and zoanthids at shallower depths. At around 5-6 feet these species give way to elkhorn, star, and brain corals along with sea fans, seawhips, and sea plumes. [3] These spurs are formed through coral growth with Elkhorn coral playing a predominant role in reef expansion, growing at a rate of 4-5 inches a year. [2] Grooves are the sandy bottom channels that separate the spurs. These areas consist mostly coarse white limestone sand composed of fragments of shells, coral, and algae plates formed by green calcareous algae.[3][2]These regions are inhabited by smaller invertebrates that bury into the sand and only venture out at night.[3] The final section of these coral reef formations is the Forereef. This is the open-sea edge of the bank reef. At its shallowest points this section of the reef if composed primarily of Star coral and inhabited by benthic (residing on rock or sediment) organisms.[3] As depth continues to increase and becomes limiting, coral begins to form plate-like formations that increase their surface area and photosynthetic ability.[3] From here the bank reef slopes down into the depths of the ocean until sponges and non-reef building community compose the majority of the ecosystem.[3]

As is typical of most coral reefs, bank reefs have a high species diversity living in and around them. French Angelfish (Pomacanthus paru), Blue Parrotfish (Scarus coeruleus), Queen Parrotfish (Scarus vetula), Queen triggerfish (Balistes vetula), Rock beauties (Holacanthus tricolor), Goatfish (Parupeneus cyclostomus), Porkfish (Anisotremus virginicus), and Snappers (Lutjanus spp.) commonly inhabit these coral formations.[3] Crabs, lobsters, sea urchins, and other organisms are also known to reside in the small caves and tunnels that form throughout the Bank reef structure. [2]

Location

  • Found at deeper depths than other coral formations at 20-60 feet down. [4]
  • An example of one such formation is off the central east coast of Florida. Here Oculina varicosa is known to form bank reefs from the sea floor.[1]

Notes

  1. 1.0 1.1 1.2 Jaap, Walter C. "Corals and Coral Reefs." Water: Science and Issues 1 (2003): 212-20. GVRL. Cengage Learning. Web. 25 Feb. 2015.
  2. 2.0 2.1 2.2 2.3 2.4 "Cool Things: Bank Reef." Web World Wonders. Apache, n.d. Web. 25 Feb. 2015. <http://webworld.freac.fsu.edu/cameras/keys/cool/bankreef.htm>.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 "Bank Reef." South Florida Aquatic Environments. FLMNH Ichthyology Department, n.d. Web. 25 Feb. 2015. <https://www.flmnh.ufl.edu/fish/southflorida/coral/bankreef.html>.
  4. "Coral Reefs." Nature Foundation St. Maarten, 2009. Web. 25 Feb. 2015. <http://www.naturefoundationsxm.org/education/coral_reefs/coral_reefs.htm>.
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