rock infauna is predominantly fine sand and mud. The amounts of this sediment 

 are considerable: 9 tons yr~l for the urchins plus 6.5 tons yr~l for the 

 infauna at Black Rock. This sediment probably does not accumulate in the 

 shallow bank margin environment because currents are strong (Hine, et al . , 

 1981, fig. 24, p. 287). 



From the JOHNSON-SEA-LINK submersibles we observed sediment-containing 

 grooves passing through the bank-edge reefs and have counted 70 grooves in a 

 400 m long segment of bank edge west of Black Rock. Hubbard, et al . (1981, 

 fig. 17, p. 26) have illustrated similar sediment-containing grooves off Lucaya, 

 Grand Bahama Island. We made sediment trap measurements in the grooves (32 m 

 depth) west of Black Rock and found an average of 5.4 kg m~\ yr - l of carbonate 

 sediment moving westward. We suggest that this sediment, in part, represents the 

 products of urchin and rock infauna bioerosion being transported over the bank 

 edge and into deeper waters of the Northwest Providence Channel. 



ACKNOWLEDGMENTS 



We thank the officers and crews of R/V JOHNSON and JOHNSON-SEA-LINK I for 

 their expert assistance at sea; Craig Caddigan, Chris Chulamanis, and Richard 

 Morris who assisted with SCUBA diving in deployment and recovery of the bucket 

 experiments; David Mook for Cal Comp plotting; and Marjorie Reaka and two 

 anonymous reviewers for manuscript editing. This is Contribution No. 390 from 

 Harbor Branch Foundation, Inc. 



LITERATURE CITED 



Davies, T. T. , M. A. Crenshaw, and B. M. Heatfield. 1972. "The Effect of 

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Hine, A. C, R. J. Wilber, and A. C. Neumann. 1981. "Carbonate Sand Bodies 

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 Bahamas." Bull. Amer. Assoc. Petrol. Geo! . 65:261-290. 



Hopley, D. 1982. The Geomorphology of the Great Barrier Reef: Quaternary 

 Development of Coral Reefs . Wi ley-Interscience, New York. 453 pp. 



Hubbard, D. K. , L. G. Ward, D. M. Fitzgerald, and A. C. Hine. 1976. "Bank 

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 No. 7-CRD, Coastal Res. Div., Univ. of South Carolina, Columbia, S.C. 36 pp. 



Hughes Clark, M. W. , and A. J. Keij. 1973. "Organisms as Producers of Carbonate 

 Sediment and Indicators of Environment in the Southern Persian Gulf," pp. 33- 

 56. _Itk B. Purser (ed.), The Persian Gulf . Springer-Verlag, New York. 



Hunt, M. 1969. "A Preliminary Investigation of the Habits and Habitat of the 

 Rock-Boring Urchin Echinometra lucunter near Devonshire Bay, Bermuda," pp. 

 35-40. _I_n: R. N. Ginsburg and P. Garrett (eds.), Seminar on Organism- 

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