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Species Description:
Occulina diffusa generally forms dense colonies
up to 12 inches in diameter on short, crooked branches. Color is often a
yellow-brown, but this feature can be obscured by other organisms which encrust
the coral. This species prefers shallow areas high in sedimentation, to
depths of 3 - 75 feet, though it rarely occurs below 40 feet.
II. HABITAT AND
DISTRIBUTION
Regional Occurrence:
Oculina diffusa occurs in
Florida, Bermuda, the Bahamas and the West Indies.
IRL Distribution:
While it does occur within the Indian River Lagoon, O. diffusa is
found primarily on nearshore reefs off east central Florida.
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Colonies grow to approximately 1 foot in diameter, with branches generally
less than 1/2 inch in diameter.
Abundance:
Oculina diffusa is common in nearshore reefs off Florida, though it
can be found within the Indian River Lagoon, especially around inlet areas.
Locomotion:
Sessile.
Reproduction:
Single polyps which have been sexually produced settle and attach to a
substratum where they bud asexually to give rise to entire colonies.
IV. PHYSICAL TOLERANCES
Temperature:
Reef temperatures recorded for Oculina diffusa off Fort Pierce, Florida
ranged from 13 - 31 °C and averaged 24.6 °C.
Salinity:
Salinities recorded for Oculina diffusa off Ft. Pierce, Florida
ranged from 26 - 36.4 ppt. In the Indian River Lagoon, salinities for O.
diffusa may be as low as 15 ppt.
V. COMMUNITY ECOLOGY
Trophic Mode:
O. diffusa feeds on plankton and tiny fish; it may also
suspension feed to a smaller extent using mucous films to trap fine particles.
Habitat:
Oculina diffusa can be found on nearshore limestone ledges of 0.5 -
2.0 m relief. It is also found in the Indian River Lagoon and the
Intracoastal Waterway, Typically, it is found at depths of 2 - 3 meters,
up to 10 - 20 meters.
VI. SPECIAL STATUS
Special Status:
Habitat Structure
Notes on Special Status:
O. diffusa colonies provide habitat for a variety of invertebrates
and fish species.
Benefit in the IRL:
Oculina diffusa has a positive economic impact in the Indian River
Lagoon by providing habitat for commercially and recreationally important fish
and crustaceans, as well as some mollusks and annelids.
Economic Importance:
None
Report by: J. Dineen,
Smithsonian Marine Station
with thanks to J. Reed, HBOI
Submit additional information, photos or comments to:
irl_webmaster@si.edu
Page last updated: July 25, 2001
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