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Species Description:
In shallow waters (2 - 40 m), Oculina varicosa often occurs as
a semi-isolated, low-growing colony, patchily distributed on coquinoid reef. However, in deeper water (70 -100 m) it can occur as a massive,
coalescing aggregate having substantial topographical relief. Colors range
from yellow-brown to lavender.
Potentially Misidentified Species:
Oculina diffusa, Oculina arbuscula, Oculina valenciennesi
II. HABITAT AND
DISTRIBUTION
Regional Occurrence:
Oculina varicosa occurs from
the east Florida coast to North Carolina, Bermuda and the West Indies (Reed et
al 1982).
IRL Distribution:
Oculina varicosa occurs sparsely in the Indian River Lagoon and on ledges
in intracoastal waterways. O. varicosa occurs abundantly on shallow (6 m)
near-shore reefs and on shelf edge banks (80 m) off east central Florida.
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Size range in Oculina varicosa found in shallow water is from 10
- 25 cm, with an average size of 15 cm. Deep water specimens can
range from 25 - 150 cm; with a typical size of 100 cm.
Growth rates are apparently somewhat higher in
deeper water than in shallow water. Growth for this species at 6 m
depth was 11.3 mm per year; however, at 80 m depth, growth rate of Oculina
varicosa was 16.1 mm per year. Based on growth rates of 16 mm/yr,
large colonies of Oculina varicosa could exceed 100 years of age.
Embryology:
Egg development time of Oculina varicosa in the laboratory is
approximately 12 hours. The planula larva is most likely lecithotrophic and takes
18 - 22 days for development at 16 ºC, in the laboratory.
IV. PHYSICAL TOLERANCES
Temperature:
Reef temperatures recorded for Oculina varicosa off Fort Pierce, Florida
ranged from 7 - 31 °C and averaged 15 - 25 °C.
Salinity:
In the Indian River Lagoon, recorded salinities
ranged from 15 - 36.5 ppt. Off Fort Pierce, Florida, reef salinities for
this species ranged from 28 - 36.4 ppt.
V. COMMUNITY ECOLOGY
Trophic Mode:
O. varicosa feeds on plankton and tiny fish. It may also
suspension feed using mucous strands.
Habitat:
Oculina varicosa grows on low and medium relief limestone ledges (0.5
- 3.0 m) and on high relief shelf edge pinnacles (25 m relief). Benthic depth
range for O. varicosa is 3.0 - 150.0 meters. Oculina varicosa can
withstand moderate wave exposure on near-shore reefs (3.0 - 5.0 m deep).
VI. SPECIAL STATUS
Special Status:
Habitat Structure
Benefit in the IRL:
Oculina varicosa provides habitat for a high diversity of invertebrates
including crustaceans (Reed et al 1982) , mollusks (Reed & Mikkelsen 1987),
fish, annelids and sipunculan worms.
Economic Importance:
Oculina varicosa provides nursery and habitat for commercially and
recreationally important fish including grouper and snapper.
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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